WO2025259148A1

WO2025259148A1 - A pulsed power drilling system, drill rig and method for reducing the risk of electric discharge

Info

Publication number: WO2025259148A1
Application number: PCT/SE2024/050570
Authority: WO
Inventors: Erik JAKOBSSON; Andre SKYTTEDAL; Harald Franz Arno Merkel; Pedjman POURMOHAMADIYAN
Original assignee: Epiroc Rock Drills AB
Current assignee: Epiroc Rock Drills AB
Priority date: 2024-06-11
Filing date: 2024-06-11
Publication date: 2025-12-18
Anticipated expiration: 2026-12-11

Abstract

The technology disclosed relates to a pulsed power drilling system, a drill rig comprising the pulsed power drilling system and methods for applying electrically insulating material on isolator surfaces of high voltage connectors for the purpose of reducing the risk of electrical discharges and improving the lifetime and performance of pulsed power drilling systems. The disclosed pulsed power drilling system and methods may for example be applied in rock drilling, concrete processing, mineral processing, material fragmentation and continuous mining. The present disclosure further relates to a drill rod to be used by a pulsed power drilling system and the use of a pulsed power drilling system.

Description

TITLE

A pulsed power drilling system, drill rig and method for reducing the risk of electric discharge

TECHNICAL FIELD

The present disclosure relates to a pulsed power drilling system, a drill rig comprising the pulsed power drilling system and methods for reducing the risk of electric discharge and improving the lifetime and performance of pulsed power drilling systems. The disclosed pulsed power drilling system and methods may for example be applied in rock drilling, concrete processing, mineral processing, material fragmentation and continuous mining. The present disclosure further relates to a drill rod to be used by a pulsed power drilling system and the use of a pulsed power drilling system.

BACKGROUND

In the field of rock drilling, a new technology has emerged during recent years, referred to as pulsed power drilling. The technology relies on the application of high voltage electric pulses between electrodes of a drill head to allow for a high voltage current pulse to pass between the electrodes via a material substrate, typically a rock. The discharge occurring, if successful, penetrates the rock material and breaks loose small pieces of rock.

Connecting high voltage cables are today typically manual, rare events. No application is known where high voltage connectors are repeatedly connected hundreds of times a day. Especially not in dirty mining environments. Any form of repeated joining of high voltage connectors such as drilling rods is likely to experience problems with poor connection quality. Simply pressing two insulators together will not eliminate gas, such as air, which will be present at the interface of the two insulating surfaces when the insulators of two high voltage connectors, e.g., drill rods, are joined together. Such gas inclusions typically cause undesirable electric discharge and poor life for the high voltage joints. An electric discharge is an electrical breakdown of gas that produces a prolonged electrical discharge.

Electric discharge issues caused by trapped gas such as air become particularly challenging for certain drilling system when high voltage connectors are repeatedly connected tens or even hundreds of times a day and in dirty mining environments in which gas is more prone to be trapped at the interface between insulators of high voltage connectors joined together to form a high voltage connector joint, as will be the scenario for pulsed power drilling systems. For these high voltage pulsed power drilling systems, it is therefore of particular importance to prevent any form of gas inclusion, e.g., air inclusion, on or close to the interface between connection surfaces of the insulating portions when joining the connecting surfaces of the insulating portions of two high voltage connectors together to form a high voltage conductor joint.

SUMMARY

In light of the foregoing discussion, there exists a need to overcome the aforementioned drawbacks associated with conventional pulsed power drilling tools.

A primary object of the technology disclosed is to mitigate issues with electrical discharges in pulsed power drilling systems when insulating portions of two separate high voltage connectors are joined together.

The object of the technology disclosed is to provide a pulsed power drilling system, a drill rig and methods for mitigating electrical discharge issues when the insulators of two high voltage connectors are joined together. Another object of the technology disclosed is to improve the lifetime and performance of high voltage pulsed power drilling systems.

For high voltage pulsed power drilling system, it is of particular importance to avoid any form of gas inclusions, e.g., air inclusions, on or close to the connection surfaces of the insulation compartments when connecting the surfaces of the insulating portions of two high voltage connectors together to form a high voltage conductor joint.

The technology disclosed is therefore aimed at preventing gas inclusions, or at least reducing the amount of gas inclusions, at the interface of the insulation compartments of a high voltage connection when pressing the connecting surfaces of the insulating portions of two high voltage connectors together to form a high voltage conductor joint. According to an aspect of the technology disclosed, at least the primary object is achieved by a pulsed power drilling system according to claim 1 , hereinafter also refer to as a drilling tool.

This disclosure relates to a pulsed power drilling system comprising a pulsed power generator system for generating high voltage current pulses and that is configured for passing a pulsed electrical current through a mineral substrate to break the mineral substrate. In addition, the pulsed poser drilling system of the technology disclosed typically comprise a drill head having a plurality of electrodes for carrying high voltage electric pulses generated by the pulsed power generator. According to the technology disclosed, the pulsed power drilling system further comprises an applicator device configured to apply electrically insulating material on connecting surfaces of high voltage connectors.

In aspects, the technology disclosed relates to a pulsed power drilling system comprising a pulsed power generator for generating high voltage electric pulses and an applicator device configured to apply electrically insulating material on at least portions of the connecting surfaces of an insulating portion of a high voltage connector that further comprises a high voltage electrode portion for carrying high voltage electric pulses generated by the pulsed power generator.

In various embodiments, the applicator device may be configured to apply electrically insulating material in the form of at least one of grease and a lubricant composition.

In embodiments, the pulsed power drilling system further comprises a feed device including a high voltage electrode portion that is electrically connectable to the pulsed power generator and an insulating portion, and a drill rod handling device for gripping and moving high voltage connectors in the form of drill rods.

In embodiments, the pulsed power drilling system further comprises a control system including processing circuitry configured to control the application of the electrically insulating material by the applicator device so that the electrically insulating material is applied on at least portions of the connecting surfaces of the insulating portion of a high voltage connector during a time period when the high voltage connector is disconnected from other high voltage connectors. In embodiments, the processing circuitry of the control system is configured to control the applicator device to apply electrically insulating material on the connecting surfaces of the insulating portion of a high voltage connector so that the electrically insulating material is applied during a portion of a time period when an open end of the high voltage connector is electrically and mechanically disconnected from other high voltage connectors.

In embodiments, the processing circuitry of the control system is configured to control the applicator device to apply electrically insulating material on connecting surfaces of the insulating portion of a high voltage connector so that the electrically insulating material is present on the connecting surfaces of the insulating portion when connecting the connecting surfaces of the insulating portion of the high voltage connector to corresponding connecting surfaces of the insulating portion of another high voltage connector to form a high voltage connector joint, or high voltage conductor joint.

In embodiments, the pulsed power drilling system comprises an arrangement for moving the applicator device and bring the applicator device in position for applying the electrically insulating material on connecting surfaces of the insulating portion of a high voltage connector.

In certain embodiments, the arrangement for moving the applicator device may be configured to bring the applicator device in position for applying the electrically insulating material after the high voltage connector has been disconnected from a high voltage connector/ conductor joint and before the high voltage connector is mechanically and electrically connected to another high voltage connector to form a new high voltage connector /con du ctor joint.

In embodiments, the pulsed power drilling system comprises a drill rod handling device configured to grip and move a high voltage connector in the form of a drill rod so that the connecting surfaces of the drill rod is positioned to be aligned with corresponding connecting surfaces of another high voltage connector. The processing circuitry of the control system may then be configured to control the applicator device so that electrically insulating material is applied on connecting surfaces of the insulating portion of at least one of said drill rod and another high voltage connector, e.g., another drill rod or a feed device, during a portion of a time period when the connecting surfaces of the drill rod are positioned to be aligned with corresponding connecting surfaces of the other high voltage connector and before the drill rod is mechanically and electrically connected to the other high voltage connector to form a high voltage connector joint.

In embodiments, the arrangement for moving the applicator device is configured to bring the applicator device in at least one position for applying the electrically insulating material on at least portions of the connecting surfaces of the insulating portion of at least one of a first high voltage connector in the form of a first drill rod and a second high voltage connector in the form of a second drill rod that is to be mechanically and electrically connected to the first drill rod.

In embodiments, the arrangement for moving the applicator device is configured to bring the applicator device in at least one position for applying the electrically insulating material on at least portions of the connecting surfaces of the insulating portion of at least one of a first high voltage connector in the form of a feed device of the pulsed power drilling system that is electrically connectable to the pulsed power generator and a second high voltage connector in the form of a drill rod that is to be mechanically and electrically connected to the feed device.

In embodiments, the feed device is configured to retract after having been disconnected from a drill rod. The processing circuitry of the control system may then be configured to control the applicator device so that electrically insulating material is applied on connecting surfaces of the insulating portion of the feed device when the feed device is in its retracted position.

In embodiments, the drill rod handling device may be configured to grip a drill rod and position the drill rod into place to be aligned with the retracted feed device. The processing circuitry of the control system may then be configured to control the drill rod handling device so that the applicator device applies the electrically insulating material on exposed connecting surfaces of the insulating portion of the drill rod before the drill rod is mechanically and electrically connected to the feed device to form a high voltage connector joint, or high voltage conductor joint.

In embodiments, the feed device is electrically connectable to the pulsed power generator and comprises a recess or channel configured to form a flow path channel that extends from a first interior point to a second exterior point of a high voltage connection when the feed device is mechanically and electrically connected with another high voltage connector in the form of a drill rod to form a high voltage connector joint, so as to allow for electrically insulating material present on at least a portion of the insulating connection surfaces of at least one of two opposite insulating connection surfaces to flow from the first interior point to the second exterior point by means of the mechanical force applied when mechanically connecting the feed device with the drill rod.

In aspects, the technology disclosed relates to a drill rod comprising an insulating portion and a high voltage electrode portion for carrying high voltage electric pulses generated by a pulsed power generator, where the drill rod comprises a recess or channel configured to form a flow path channel that extends from a first interior point to a second exterior point of a high voltage connection when the drill rod is mechanically and electrically connected with another high voltage connector, e.g., another drill rod or a feed device, to form a high voltage connector joint, or high voltage conductor joint, so as to allow for electrically insulating material present on at least a portion of the insulating connection surfaces of at least one of two opposite insulating connection surfaces, including the insulating connection surfaces of the drill rod, to flow from the first interior point to the second exterior point by means of the mechanical force applied when connecting the drill rod with another high voltage connector.

In embodiments, the pulsed power drilling system may further comprise a cleaning arrangement including a cleaning device configured for cleaning the connecting surfaces of an insulating portion of a high voltage connector prior to applying, by the applicator device, electrically insulating material on the connecting surfaces of the insulating portion.

In embodiments, the pulsed power drilling system may comprise both an applicator device and a cleaning device. The processing circuitry of the control system of the pulsed power drilling system may then be configured to control both the applicator device and the cleaning device so that the cleaning device is cleaning the connecting surfaces of an insulating portion of a high voltage connector, for example a drill rod or a feed device, when the free end of the conductor comprising the insulating portion is disconnected from other high voltage connectors and before the applicator device is applying electrically insulating material on the connecting surfaces of the same insulating portion and the high voltage connector is connected to a new high voltage connector.

In embodiments, the pulsed power drilling system comprises a combined cleaning and applicator arrangement configured both for cleaning connecting surfaces of an insulating portion of a high voltage connector and applying electrically insulating material on the same connecting surfaces of the high voltage connector. The arrangement for both cleaning the connecting surfaces and applying electrically insulating material on the same connecting surfaces may then include a cleaning device comprising at least one of a nozzle for spraying a compressed gas on a connecting surface of an insulating portion, a mechanical brush for cleaning a connecting surface of an insulating portion and an applicator for applying a cleaning agent onto a connecting surface of an insulating portion. Processing circuitry of the control system may then be configured to control the cleaning device and the applicator device of the arrangement so that the connecting surfaces of the insulating portion are cleaned prior to applying, by the same arrangement, electrically insulating material on portions of the same connecting surfaces of the insulating portion of the same high voltage connector.

In embodiments, the pulsed power drilling system comprises an arrangement for moving the combined cleaning and applicator arrangement so that the cleaning device and the applicator device are each in position for first cleaning connecting surfaces of the insulating portion of a high voltage connector and then applying the electrically insulating material on at least portions of the same connecting surfaces of the insulating portion of the high voltage connector. The arrangement for moving the applicator device may be configured to bring the cleaning device of the combined cleaning and applicator arrangement in position for both cleaning connecting surfaces of the insulting portion of the high voltage connector and applying, by the applicator device of the same combined cleaning and applicator arrangement, electrically insulating material after the high voltage connector has been disconnected from a high voltage connector joint and before the high voltage connector is mechanically and electrically connected to another high voltage connector to form a new high voltage connector joint, or high voltage conductor joint.

In certain embodiments, the cleaning arrangement may comprise a separate arrangement for moving the cleaning device to bring the cleaning device in position for cleaning the connecting surfaces of an insulating portion of the feed device prior to applying, by the applicator device, electrically insulating material on the connecting surfaces of the insulating portion of at least one of the feed device and a drill rod to be mechanically and electrically connected to the feed device to form a high voltage connector joint.

In certain embodiments, the cleaning arrangement may comprise an arrangement for moving the cleaning device to bring the cleaning device in position for cleaning the connecting surfaces of an insulating portion of a drill rod that is positioned to be aligned with the feed device prior to applying, by the applicator device, electrically insulating material on the connecting surfaces of the insulating portion of the drill rod.

In certain embodiments, the processing circuitry of the control system may be configured to control the arrangement for moving the cleaning device so that the cleaning device is in position for cleaning connecting surfaces of the insulating portion of at least one of the feed device and a high voltage connector in the form of a drill rod to be connected to the feed device during a portion of a time period after the feed device has been mechanically and electrically disconnected from a high voltage connector in the form of another drill rod and before applying, by the applicator device, electrically insulating material on the connecting surfaces of the insulating portion of at least one of the feed device and said drill rod to be connected to the feed device.

In various embodiments, the cleaning device may comprise at least one of a nozzle for spraying a compressed gas on a connecting surface of an insulating portion, a mechanical brush for cleaning a connecting surface of an insulating portion and an applicator for applying a cleaning agent onto a connecting surface of an insulating portion.

In aspects, the technology disclosed relates to a drill rod comprising an insulating portion and a high voltage electrode portion for carrying high voltage electric pulses generated by a pulsed power generator. The high voltage electrode portion of the drill rod is configured to be electrically connected to the high voltage electrode portion of another drill rod or to the high voltage electrode portion of a feed device of the pulsed power drilling system to thereby form a high voltage connector joint. The insulating portion of the drill rod is configured to be connected to the insulating portion of another drill rod and / or the insulating portion of a feed device of the pulsed power drilling system. According to aspects of the technology disclosed, the drill rod further comprises a recess or channel configured to form a flow path channel that extends from a first interior point to a second exterior point of a high voltage connection when the drill rod is mechanically and electrically connected /joined with another high voltage connector, e.g., another drill rod or a feed device, to form a high voltage connector joint, or high voltage conductor joint, so as to allow for electrically insulating material present on at least a portion of the insulating connection surfaces of at least one of two opposite insulating connection surfaces, including the insulating connection surfaces of the drill rod, to flow from the first interior point to the second exterior point by means of the mechanical force applied when connecting the drill rod with another high voltage connector by pressing the connecting surfaces of the respective insulting portions together.

In aspects, the technology disclosed relates to a method for mechanically and electrically connecting a first high voltage connector to a second high voltage connector in a pulsed power drilling system comprising a control system including processing circuitry, a pulsed power generator for generating high voltage electric pulses, a feed device comprising of an insulating portion and a high voltage electrode portion that is electrically connectable to the pulsed power generator, and a drill rod handling device for gripping and moving high voltage connectors in the form of drill rods, the pulsed power drilling system further comprises an applicator device configured to apply electrically insulating material, the method comprising:

- applying, by the applicator device and under the control of the processing circuitry of the control system, electrically insulating material on at least portions of the connecting surfaces of an insulating portion of a first high voltage connector that further comprises a high voltage electrode portion for carrying high voltage electric pulses,

- mechanically and electrically connecting the first high voltage connector to a second high voltage connector,

- generating, by the pulsed power generator, a high voltage electric pulse, and - passing the generated high voltage electric pulse via the high voltage connector joint.

In embodiments, the pulsed power system further comprises an arrangement for moving the applicator device, and the method is further comprising:

- moving, by means of the arrangement for moving the applicator device, the applicator device in position for applying electrically insulating material on the at least portions of the connecting surfaces of the insulating portion of the first high voltage connector, wherein the applicator device is thereby brought in position prior to applying the electrically insulating material.

In embodiments, the pulsed power system further comprises a cleaning arrangement including a cleaning device, and the method is further comprising:

- cleaning, by means of the cleaning device, connecting surfaces of the insulating portion of a high voltage connector prior to applying electrically insulating material on at least portions of the same connecting surfaces of the insulating portion of the high voltage connector.

In embodiments, the pulsed power system further comprises an arrangement for moving the cleaning device, and the method is further comprising:

- moving, by means of the arrangement for moving the cleaning device, the cleaning device in position for cleaning the connecting surfaces of the insulating portion of a high voltage connector.

In certain embodiments, the first high voltage connector may then be a first drill rod, or drill string component, and the second high voltage connector may be a second drill rod, wherein at least one of the first drill rod and the second drill rod comprises a recess or channel configured to form a flow path channel that extends from a first interior point to a second exterior point of a high voltage connection when the first drill rod is mechanically connected with the second drill rod to form a high voltage connector/ conductor joint, the method further comprising:

- applying a mechanical force when mechanically connecting the first drill rod with the second drill rod, so that at least a portion of the applied electrically insulating material is forced / pushed away by mechanical force from the connecting surfaces of an insulating portion to the formed flow path channel to thereby force away gas such as air present on or close to the connecting surfaces of the insulating connection formed when connecting the connecting surfaces of the insulating portion of the first drill rod to corresponding connecting surfaces of the insulating portion of the second drill rod.

In certain embodiments, the first high voltage connector may then be the feed device and the second high voltage connector is a drill rod, wherein at least one of the feed device and said drill rod comprises a recess or channel configured to form a flow path channel that extends from a first interior point to a second exterior point of a high voltage connection when the feed device is mechanically connected with another high voltage connector in the form of the drill rod to form a high voltage connector /con du ctor joint, the method further comprising:

- applying a mechanical force when mechanically connecting the first high voltage connector in the form of the feed device with the second high voltage connector in the form of a drill rod, so that at least a portion of the applied electrically insulating material is pushed away from the connecting surfaces of an insulating portion to the formed flow path channel to thereby force away gas such as air present on or close to the connecting surfaces of the insulating connection formed when connecting the connecting surfaces of the insulating portion of the feed device to corresponding connecting surfaces of the insulating portion of the drill rod.

In embodiments, the above-mentioned step of applying includes applying the electrically insulating material on the connecting surfaces of an insulating portion of a high voltage connector in the form of a drill rod that comprises a recess or channel configured to form a flow path channel that extends from a first interior point to a second exterior point of a high voltage connection when the drill rod is mechanically connected with another high voltage connector to form a high voltage connector joint, and the method is further comprising:

- positioning, by means of the drill rod handling device for gripping and moving high voltage connectors in the form of drill rods, the drill rod so that the drill rod is aligned with another high voltage connector, and

- applying a mechanical force when mechanically connecting the connecting surfaces of the insulating portions of the drill rod with the connecting surfaces of the insulating portions of another high voltage connector, at least a portion of the applied electrically insulating material through portions of the flow path channel to thereby force away gas such as air present on or close to the interface between the connecting surfaces of the insulating portions of the drill rod and the other high voltage connector.

In embodiments, the feed device further comprises a detector for detecting whether gas is present in an insulating connection between the feed device and a high voltage connector in the form of a drill rod, and the method is comprising: obtaining, by use of the detector, sensor data indicating whether gas such as air is present in an insulating connection of a high voltage connector joint including the feed device and a first drill, and determining, by the processing circuitry of the control system, whether gas is present in the insulating connection of a high voltage connector joint including said feed device and the first drill, and, upon determining that gas is present in the insulating connection of a high voltage connector joint including the feed device and the first drill: disconnecting the first drill rod from the feed device, and applying electrically insulating material to the connecting surfaces of the insulating portion of at least one of the feed device and a new drill rod to be connected to the feed device.

The technology disclosed further relates to a drill rig comprising a pulsed power drilling system according to any one of the embodiments disclosed herein for breaking of a mineral substrate, such as in any one of rock drilling, concrete processing, mineral processing, material fragmentation and continuous mining.

Further advantages and advantageous features of the disclosure are disclosed in the following description and in the dependent claims.

BRIEF DESCRIPTION OF THE DRAWINGS

In the following, the technology disclosed will be described in detail, with reference to exemplifying embodiments and to the enclosed drawings.

In the drawings:

Fig. 1 schematically illustrates a general pulsed power drilling system, Fig. 2 schematically illustrates a pulsed power drilling system according to an embodiment of the disclosure,

Fig. 3a schematically illustrates two high voltage connectors according to an embodiment of the disclosure,

Fig. 3b schematically illustrates two high voltage connectors according to an embodiment of the disclosure,

Fig. 4a schematically illustrates two high voltage connectors according to an embodiment of the disclosure,

Fig. 4b schematically illustrates two high voltage connectors according to an embodiment of the disclosure,

Fig. 5 schematically illustrates two high voltage multi-connectors according to an embodiment of the disclosure,

Fig. 6 is a flow-chart illustrating steps of a method according to an embodiment of the disclosure, and

Fig. 7 schematically illustrates a rock drilling machine, or drill rig, configured for comprising any of the pulsed power drilling system shown in Figs. 1 and 5.

The drawings show diagrammatic, exemplifying embodiments of the present disclosure and are thus not necessarily drawn to scale. It shall be understood that the embodiments shown and described are exemplifying and that the disclosure is not limited to these embodiments. It shall also be noted that some details in the drawings may be exaggerated in order to better describe and illustrate the disclosure. Like reference characters refer to like elements throughout the description, unless expressed otherwise.

DETAILED DESCRIPTION OF EXAMPLE EMBODIMENTS OF THE DISCLOSURE

The following detailed description illustrates embodiments of the present disclosure and ways in which they can be implemented. Although some modes of carrying out the present disclosure have been disclosed, those skilled in the art would recognize that other embodiments for carrying out or practicing the present disclosure are also possible.

The basic concept of the technology disclosed is to apply electrically insulating material on connecting surfaces of an insulating portion of high voltage connectors for the purpose of reducing the risk of electric discharge when connecting high voltage connectors to form a high voltage conductor joint, thereby also improving the lifetime and performance of pulsed power drilling systems configured for mechanically and electrically connecting the high voltage connectors.

The inventors have realized that there is a need in the drilling industry for reducing the risk of electrical discharges and improving the lifetime and performance of pulsed power drilling systems. The inventors proposes a pulsed power drilling system and method for first applying electrically insulating material on connecting surfaces of insulating portions of high voltage connectors and then forcing away trapped gas such as air from the connecting surfaces of the insulation compartments of the connection by means of the applied electrically insulating material and the mechanical force applied when pressing/joining the connecting surfaces of two high voltage connectors together to form a high voltage connector / conductor joint.

The disclosed pulsed power drilling system and methods may for example be applied in rock drilling, concrete processing, mineral processing, material fragmentation and continuous mining. The present disclosure further relates to a drill rod to be used by a pulsed power drilling system and the use of a pulsed power drilling system.

In various embodiments, the feed device and/or the drill rod is a high voltage connector that comprises a recess or channel configured to form a flow path channel (e.g., formed by joining two connecting surfaces and/or recesses together) that extends from a first interior point to a second exterior point of a high voltage connection when the feed device is mechanically and electrically connected /joined with another high voltage connector in the form of a drill rod to form a high voltage connector joint, or high voltage conductor joint, so as to allow for electrically insulating material present on at least a portion of the insulating connection surfaces of at least one of two opposite insulating connection surfaces to flow from the first interior point to the second exterior point by means of the mechanical force applied when mechanically connecting/joining the two high voltage connectors, for example mechanically (and electrically) connecting two drill string components such as two drill rods or mechanically (and electrically) connecting the feed device with a new drill rod.

The pulsed power drilling system according to example embodiments may comprise both an arrangement comprising cleaning device and an arrangement comprising an applicator device for applying electrically insulating material on connecting surfaces of insulating portions of high voltage connectors, or the same arrangement may comprise both the cleaning device and the applicator device.

In embodiments, the pulsed power drilling system comprises an arrangement for moving the combined cleaning and applicator arrangement so that the cleaning device and the applicator device are each in position for first cleaning and subsequently applying the electrically insulating material on the connecting surfaces of the insulating portion of the high voltage connector. The arrangement for moving the applicator device may be configured to bring the cleaning device of the combined cleaning and applicator arrangement in position for both cleaning the connecting surfaces of the insulting portion of the high voltage connector and the applicator device of the same combined cleaning and applicator arrangement in position for applying the electrically insulating material after the high voltage connector has been disconnected from a high voltage connector joint and before the high voltage connector is mechanically and electrically connected to another high voltage connector to form a new high voltage connector /con du ctor joint.

The technology disclosed relates to a pulsed power drilling system that comprises a pulsed power generator for generating high voltage electric pulses, a feed device typically comprising an insulating portion and a high voltage electrode portion that is electrically connectable to the pulsed power generator, and a drill rod handling device for gripping and moving high voltage connectors in the form of drill rods.

According to the technology disclosed, the pulsed power drilling system further comprises a control system including processing circuitry and an applicator device configured to apply electrically insulating material on at least portions of the connecting surfaces of an insulating portion of a high voltage connector that further comprises a high voltage electrode portion for carrying high voltage electric pulses generated by the pulsed power generator. The applicator device may be configured to apply electrically insulating material in the form of at least one of grease, such as high voltage grease, and a lubricant composition.

In embodiments, the processing circuitry of the control system may be configured to control the application of the electrically insulating material by the applicator device so that the electrically insulating material is applied during a portion of a time period when the high voltage connector is disconnected from other high voltage connectors.

In embodiments, the processing circuitry of the control system may be configured to control the applicator device to apply electrically insulating material on the connecting surfaces of the insulating portion of the high voltage connector so that the electrically insulating material is applied during a portion of a time period when an open end of the high voltage connector comprising the connecting surfaces of the insulating portion is electrically and mechanically disconnected from other high voltage connectors.

In embodiments, the processing circuitry of the control system may be configured to control the applicator device to apply electrically insulating material on connecting surfaces of the insulating portion of the high voltage connector so that the electrically insulating material is present on the connecting surfaces of the insulating portion when connecting the connecting surfaces of the insulating portion of the high voltage connector to corresponding connecting surfaces of the insulating portion of another high voltage connector to form a high voltage connector joint. After applying the electrically insulating material on connecting surfaces of the insulating portions of at least one of the two high voltage connectors, the first and second high voltage connectors are electrically connected to each other by joining connecting surfaces of their respective high voltage electrode portions together to thereby form a high voltage connector joint, or high voltage conductor joint.

In embodiments, the pulsed power drilling system comprises an arrangement for moving the applicator device and bring the applicator device in position for applying the electrically insulating material on connecting surfaces of the insulating portion of the high voltage connector. The arrangement for moving the applicator device may then be configured to bring the applicator device in position for applying the electrically insulating material after the high voltage connector has been disconnected from a high voltage connector joint and before the high voltage connector is mechanically and electrically connected to another high voltage connector to form a new high voltage connector joint, or high voltage conductor joint. The arrangement for moving the applicator device may then be configured to bring the applicator device in at least one position for applying the electrically insulating material on at least portions of the connecting surfaces of the insulating portion of at least one of a first high voltage connector in the form of a first drill rod and a second high voltage connector in the form of a second drill rod that is to be mechanically and electrically connected to the first drill rod. After applying the electrically insulating material on connecting surfaces of the insulating portions of at least one of the two drill rods, the first and second drill rod are electrically connected to each other by joining connecting surfaces of their respective high voltage electrode portions together to thereby form a high voltage connector joint, or high voltage conductor joint.

In embodiments, the arrangement for moving the applicator device may further be configured to bring the applicator device in at least one position for applying the electrically insulating material on at least portions of the connecting surfaces of the insulating portion of at least one of a first high voltage connector in the form of the feed device and a second high voltage connector in the form of a drill rod. The feed device may then be configured to retract after having been disconnected from a first drill rod. The processing circuitry of the control system is configured to control the applicator device so that electrically insulating material is applied on connecting surfaces of the insulating portion of the feed device when the feed device is in its retracted position.

In embodiments, the processing circuitry of the control system may be configured to control the arrangement for moving the applicator device so that the applicator device is in position for and is applying electrically insulating material on connecting surfaces of the insulating portion of the feed device during a portion of a time period after the feed device has been mechanically and electrically disconnected from a first high voltage connector in the form of a first drill rod and before the feed device is mechanically and electrically connected to a second high voltage connector in the form of a second drill rod.

The pulsed power system may further comprise a cleaning arrangement including a cleaning device and configured for cleaning the connecting surfaces of an insulating portion of a high voltage connector prior to applying, by the applicator device, electrically insulating material on the connecting surfaces of the insulating portion. In various embodiments, the cleaning device may comprise at least one of a nozzle for spraying a compressed gas on a connecting surface of an insulating portion, a mechanical brush for cleaning a connecting surface of an insulating portion and an applicator for applying a cleaning agent onto a connecting surface of an insulating portion.

The cleaning arrangement may further comprise an arrangement for moving the cleaning device to bring the cleaning device in position for cleaning the connecting surfaces of an insulating portion of the feed device prior to applying, by the applicator device, electrically insulating material on the connecting surfaces of the insulating portion of at least one of the feed device and a drill rod to be mechanically and electrically connected to the feed device to form a high voltage connector joint. The cleaning arrangement may then typically comprise an arrangement for moving the cleaning device to bring the cleaning device in position for cleaning the connecting surfaces of an insulating portion of a drill rod that is positioned to be aligned with the feed device prior to applying, by the applicator device, electrically insulating material on the connecting surfaces of the insulating portion of the drill rod. The processing circuitry of the control system may then be configured to control the arrangement for moving the cleaning device so that the cleaning device is in position for cleaning connecting surfaces of the insulating portion of at least one of the feed device and a high voltage connector in the form of a drill rod to be connected to the feed device during a portion of a time period after the feed device has been mechanically and electrically disconnected from a high voltage connector in the form of another drill rod and before applying, by the applicator device, electrically insulating material on the connecting surfaces of the insulating portion of at least one of the feed device and said drill rod to be connected to the feed device.

In embodiments, the cleaning arrangement may comprise a mechanical arm for holding and moving the cleaning device into place, first cleaning the high voltage joint either using compressed air or some mechanical brushing, or both, and possibly some cleaning agent such as isopropanol. Once the joints are sufficiently clean, electrically insulating material such as high voltage grease may automatically be applied to portions of the exposed connecting surfaces of the insulating portions of the high voltage connectors to be connected. The application of electrically insulating material can be done either by a mechanical brush, as the drill rod is rotated and passed by the brush, or by a grease spraying device. Once the connecting surfaces of the insulting portions are squeezed together by mechanical force, an air-free joint may be achieved.

- applying, by the applicator device and under the control of the processing circuitry of the control system, electrically insulating material on at least portions of the connecting surfaces of an insulating portion of a first high voltage connector that further comprises a high voltage electrode portion for carrying high voltage electric pulses, wherein the electrically insulating material is applied during a portion of a time period when the connecting surfaces of the insulating portion of the first high voltage connector is disconnected from other high voltage connectors,

- mechanically and electrically connecting the first high voltage connector to a second high voltage connector, wherein the applied electrically insulating material is present on the connecting surfaces of the insulating portion of the first high voltage connector when mechanically and electrically connecting the first high voltage connector to the second high voltage connector to form a high voltage connector joint,

- generating, by the pulsed power generator, a high voltage electric pulse, and

- passing the generated high voltage electric pulse via the high voltage connector joint.

- cleaning, by means of the cleaning device, said connecting surfaces of the insulating portion of the high voltage connector prior to said step of applying electrically insulating material on the at least portions of said connecting surfaces of the insulating portion of said first high voltage connector.

- moving, by means of the arrangement for moving the cleaning device, the cleaning device in position for cleaning the connecting surfaces of the insulating portion of the first high voltage connector, wherein the cleaning device is thereby brought in position for cleaning the connecting surfaces prior to applying the electrically insulating material.

In certain embodiments, the first high voltage connector may then be a first drill rod, or drill string component, and the second high voltage connector may be a second drill rod, wherein at least one of the first drill rod and the second drill rod comprises a recess or channel configured to form a flow path channel that extends from a first interior point to a second exterior point of a high voltage connection when the first drill rod is mechanically connected with the second drill rod to form a high voltage connector joint, the method further comprising:

- applying a mechanical force when mechanically connecting the first drill rod with the second drill rod, so that at least a portion of the applied electrically insulating material is pushed away from the connecting surfaces of an insulating portion to the formed flow path channel to thereby force away gas present on or close to the connecting surfaces of the insulating connection formed when connecting the connecting surfaces of the insulating portion of the first drill rod to corresponding connecting surfaces of the insulating portion of the second drill rod.

In certain embodiments, the first high voltage connector may then be the feed device and the second high voltage connector is a new drill rod, wherein at least one of the feed device and the new drill rod comprises a recess or channel configured to form a flow path channel that extends from a first interior point to a second exterior point of a high voltage connection when the feed device is mechanically connected with the new drill rod to form a high voltage connector joint, the method further comprising:

- applying a mechanical force when mechanically connecting the feed device with the new drill rod, so that at least a portion of the applied electrically insulating material is pushed away from the connecting surfaces of an insulating portion to the formed flow path channel to thereby force away gas present on or close to the insulating connection formed when connecting the connecting surfaces of the insulating portion of the feed device to corresponding connecting surfaces of the insulating portion of the new drill rod.

- passing, by means of the mechanical force applied when mechanically connecting the drill rod with the other high voltage connector, at least a portion of the applied electrically insulating material through portions of said flow path channel to thereby force away gas present on or close to said connecting surfaces of the insulating connection formed when connecting the connecting surfaces of the insulating portion of the drill rod to corresponding connecting surfaces of the insulating portion of the other high voltage connector.

In embodiments, the feed device further comprises a detector for detecting whether gas is present in an insulating connection between the feed device and a high voltage connector in the form of a drill rod, and the method is further comprising:

- detecting, by use of the detector, that gas is present in an insulating connection of a high voltage connector joint including the feed device and a first drill rod to thereby determine, by the processing circuitry of the control system, that electrically insulating material is to be applied prior to connecting the first high voltage connector in the form of the feed device to the second high voltage connector in the form of a new second drill rod, and

- disconnecting the feed device from the first drill rod prior to the step of applying electrically insulating material to the connecting surfaces of the insulating portion of at least one of the feed device and the second high voltage connector in the form of a new drill rod.

In embodiments, the pulsed power drilling system comprises a drill rod handling device configured to hold/grip and move a high voltage connector in the form of a drill rod so that the connecting surfaces of the drill rod is positioned to be aligned with corresponding connecting surfaces of another high voltage connector. The processing circuitry of the control system may then be configured to control the applicator device so that electrically insulating material is applied on connecting surfaces of the insulating portion of at least one of the drill rod and another high voltage connector during a portion of a time period when the connecting surfaces of the drill rod are positioned to be aligned with corresponding connecting surfaces of the other high voltage connector and before the drill rod is mechanically and electrically connected to the other high voltage connector to form a high voltage connector joint.

The drill rod handling device may be configured to grip a drill rod and position the drill rod into place to be aligned with the retracted feed device. The processing circuitry of the control system is configured to control the drill rod handling device so that the applicator device applies the electrically insulating material on exposed connecting surfaces of the insulating portion of the drill rod before the drill rod is mechanically and electrically connected to the feed device to form a high voltage connector joint.

In various example embodiments, the method of the technology disclosed may include drilling a first rod into the ground, disconnecting the feed device from the first drill rod, automatically apply electrically insulating material grease on exposed connecting surfaces of the insulator, or insulating portion, of the feed device, the drill rod drilled into the ground and /or a drill rod that is to be connected to the feed device or the drill rod drilled into the ground before continue drilling by generating, by the pulsed power generator, a new high voltage electric pulse. The method may typically also include aligning the new drill rod between the feed device and the drill rod drilled into the ground. In embodiments, the method may then comprise the step of automatically cleaning the connecting surfaces of the insulator of the drill rod and / or the feed device before applying the electrically insulating material on the connecting surfaces.

In embodiments, the method may then comprise the steps of automatically cleaning and / or and applying grease and /or a lubricant on connecting surfaces of the insulator of the new drill rod, attaching the new rod first to the feed device and then to the drill rod drilled into the ground before continue drilling by generating, by the pulsed power generator, a new high voltage electric pulse.

In certain embodiments, the feed device of the pulsed power drilling system is a high voltage connector comprising a high voltage electrode portion that is electrically connectable to the pulsed power generator and that is at least partly surrounded by an insulator. The insulator may then, in turn, be surrounded by a ground conductor. The feed device of the pulsed power drilling system may then be configured to be mechanically and electrically connected to a drill rod comprising a center tube forming a high voltage connector for carrying high voltage electric pulses generated by a pulsed power generator which is at least partly surrounded by an insulator tube along the length of the drill rod where the insulator tube, in turn, is at least partly surrounded by an outer tube in the form of a ground conductor.

In certain embodiments, the technology disclosed relates to a drill rod handling device for handling high voltage connectors in the form of drill string components such as drill rods in respect of a drill rig. The drill rod handling device may then include one or a plurality of gripping devices for gripping a first drill string component to be joined to a second drill string component, e.g., threaded on to or off from the second drill string component, being included in a drill string which is partly drilled into a rock formation.

The drill rod handling device may then comprise a gripping device for gripping a first drill string component, or drill rod, to be joined to connected to a second drill string component being part of a drill string which is partly drilled into a rock formation, e.g., threaded on to or off from the second drill string component, or drill rod. The drill rod handling device may further comprise a support arrangement for fastening the device for handling drill string components onto the drill rig, a handling unit which is movably connected to the support arrangement, which includes the gripping device, and which is movable between a drill string position, in which a gripped first drill string component is positioned for joining/ threading on to and off from the second drill string component. In embodiments, the joining is done with something different than threads, for example a bayonet fitting, and there may be multiple parallel conductors that are not concentric.

In embodiments, the handling unit of the drill rod handling device may include an auxiliary engagement arrangement for engaging the second drill string component, or drill rod, in the drill string positions. The handing unit with the auxiliary engagement arrangement may then be adapted for guiding and aligning the gripped first drill string component, or first drill rod, to essentially be positioned in line with an axial direction defined by the second drill string component, or second drill rod. The auxiliary engagement arrangement and the gripping device may then be arranged on a common carrier, or feed beam.

The gripping device, as well as the auxiliary engagement arrangement, may then be adjustable for gripping drill string components, or drill rods, of different dimensions with maintained alignment of gripped drill string components. The gripping device as well as the auxiliary engagement arrangement may be displaceable relative to a swing axis for adjustment purposes.

In example embodiments, the auxiliary engagement arrangement may be displaceable and fixedly supported by the carrier. In certain example embodiments, each gripping device may include a rotation wheel for thread rotation of a gripped drill string component and freely rotational rotation rollers, where at least one rotation roller is adjustable in respect of the rotation wheel.

Fig. 1 schematically illustrates an example embodiment of a general pulsed power drilling system 100. The example embodiment of a general pulsed power drilling system 100 illustrated in Fig. 1 is configured for passing a pulsed electrical current through a mineral substrate 400 to break it. The pulsed power drilling system 100 comprises a pulsed power generator 110 for generating high voltage current pulses, and a drill head 120 extending in an axial direction of the pulsed power drilling system 100 between a front end 121, configured to be positioned near or at a surface of the mineral substrate 400, and a rear end 122. In the example embodiment shown in Fig. 1, the drill head 120 comprises two electrodes 200, 200’ arranged at the front end 121 of the drill head 120, protruding slightly therefrom.

The pulsed power generator 110 of the general pulsed power drilling system 100 illustrated in Fig. 1 comprises a pulse transformer 112 in the form of a bank of capacitors, connected to an alternating current (AC) power supply 113 via a transformer and rectifier 111. The pulsed power generator 110 typically comprises a circuit (not shown) for generating a positive high voltage current pulse that is delivered to a solid electrode portion of a first electrode among the two electrodes 200, 200’ of the drill head 120 and a negative high voltage current pulse that is delivered to a solid electrode portion of a second electrode among the two electrodes 200, 200’ of the drill head 120 so as to allow a high voltage current pulse 150 to pass between the respective solid electrode portions of the first and second electrode via the mineral substrate. The two electrodes 200, 200’ may be connected to the pulsed power generator 110 by closing their respective switches 114, 114’. Fig. 1 shows the temporary closing of the two switches 114,114’ under the control of a control system 160 to generate a positive high voltage current pulse to be delivered to a solid electrode portion of a first electrode among the two electrodes 200, 200’ of the drill head 120 and a negative high voltage current pulse to delivered to a solid electrode portion of a second electrode among the two electrodes 200, 200’ of the drill head 120 so as to allow a high voltage current pulse 150 to pass between the respective solid electrode portions of the first and second electrode 200, 200’ via the mineral substrate 400.

The control system 160 in Fig. 1 may be configured to control operation of the pulsed power drilling system 100 in response to signals received from an external control unit 170, such as a control unit of a machine, e.g., drill rig, in which the pulsed power drilling system 100 is provided. The control system 160 may include processing circuitry in the form of a microprocessor, a microcontroller, a programmable digital signal processor or another programmable device. Thus, the control system 160 comprises electronic circuits and connections (not shown) as well as processing circuitry (not shown) for communicating with different parts of the pulsed power drilling system 100 as well as with the external control unit 170.

For example, the control system 160 may be configured for communicating with various sensors, for example detectors for detecting trapped air in high voltage connector joints, devices, systems and control units of the pulsed power drilling system 100. In the example embodiment shown in Fig. 1, the control system 160 controls the opening and closing of the switches 114, 114’ to thereby connect the electrodes 200, 200’ to the pulsed power generator 110 so that the electrodes 200, 200’ can carry a discharge and pass a high-voltage current pulse between them via the mineral substrate 400.

According to aspects of the technology disclosed processing circuitry of the control system 160 in Fig. 1 may be configured to control at least one of an applicator device (not shown) for applying electrically insulating material on connecting surfaces of an insulting portion of a high voltage connector such as a drill rod, a cleaning device (not shown) for cleaning connecting surfaces of an insulating portion of a high voltage connector or an arrangement for moving the applicator device and/or the cleaning device of the pulsed power drilling system 100. Fig. 2 schematically illustrates an example embodiment of a pulsed power drilling system 100 according to an embodiment of the disclosure. The pulsed power drilling system 100 shown in Fig. 2 is configured to handle, or comprise, the high voltage connectors 700, 700’, 700” of Figs. 3a, 3b, 4a, 4b and 5.

The example embodiment of a pulsed power drilling system 100 shown in Fig. 2 comprises a feed device 310 that is electrically connectable to a pulsed power generator (not shown) of the pulsed power drilling system 100, a feed beam 306, a holder device 307 attached to the feed beam 306 and configured for holding high voltage connectors in the form of drill rods 700, 700’. The high voltage connector 700” of the feed device 310 in Fig. 2 comprises an insulating portion 900” and a high voltage electrode portion 902” for carrying high voltage electric pulses generated by a pulsed power generator (not shown) . The high voltage connector 700” of the feed device 310 in Fig. 2 is configured to be mechanically and electrically connected to a drill rod 700, 700’ to form a high voltage conductor joint.

The pulsed power drilling system 100 in Fig. 2 further comprises a drill rod handling device 305 for gripping/ holding and moving drill rods 700, 700’ in place so that the drill rods 700, 700’ are aligned with the high voltage connector 700” of the feed device 310 and thereby can be mechanically and electrically connected to the high voltage connector 700” of the feed device 310.

The pulsed power drilling system 100 in Fig. 2 further comprises a drill head 120 with two electrodes 200, 200’ and a combined cleaning and applicator arrangement 300 that is attached to the feed beam 306. The combined cleaning and applicator arrangement 300 illustrated in Fig. 2 comprises a cleaning device 301 configured for cleaning connecting surfaces 901, 901’ of an insulating portion 900, 900’ of a high voltage connector 700, 700’, 700” and an applicator device 302 for applying electrically insulating material on the connecting surfaces 901, 901’ of an insulating portion 900, 900’ of two of the high voltage connectors 700, 700’ shown in Fig. 2. Each of the high voltage connectors 700, 700’, 700” in the example embodiment shown in Fig. 2 also comprises a high voltage electrode portion 902, 902’, 902” for carrying high voltage electric pulses.

The cleaning device 301 shown in Fig. 2 is a mechanical brush for cleaning a connecting surface of an insulating portion of the high voltage connector and the applicator device 302 in Fig. 2 comprises two nozzles 303, 303’ that each are in position for and configured for applying electrically insulating material on connecting surfaces 901, 901’ of the insulating portion 900, 900’ of two of the high voltage connectors 700, 700’.

In Fig. 2, the pulsed power drilling system 100 further comprises an arrangement for moving the combined cleaning and applicator arrangement 304 so that the cleaning device 301 and the applicator device 302 are in position for first cleaning, by the cleaning device, the connecting surfaces 901 of the insulating portion 900 of a first high voltage connector 700 in the form of a first drill rod and then applying, by the applicator device 302, the electrically insulating material on the connecting surfaces 901 of the insulating portion 900 of the first high voltage connector 700 in the form of a first drill rod.

In the example embodiment shown in Fig. 2, the drill string further comprises a second high voltage connector 700’ in the form of an additional, or new, second drill rod that is currently mechanically and electrically connected to another high voltage connector in the form of a feed device 700” of the pulsed power drilling system 100.

Fig. 3a shows two high voltage connectors 700, 700’ each comprising an insulating portion 900, 900’ and a high voltage electrode portion 902, 902’ for carrying high voltage electric pulses and where electrically insulating material 800 has been applied on the connecting surfaces 901 of the insulating portion 900 of a first high voltage connector 700 prior to connecting the first high voltage connector 700 to a second high voltage connector 700’. The first high voltage connector 700 in Fig. 3a comprises two recesses 810, 811 each configured to form a flow channel 820, 830 with an opposite recess 810’, 811’ of the second high voltage connector 700’ when the first and second high voltage connectors 700, 700’ are joined together.

Fig. 3b illustrates when the first high voltage connector 700 of Fig. 3a is about to be connected to the second connected 700’ of Fig. 3a. When the connecting surfaces 901, 901’ of the insulating portions 900, 900’ of the first and second high voltage connectors 700, 700’ are mechanically connected, a flow channel 820 for forcing away applied electrically insulating material 800 is formed and gas such as air present at the connecting surfaces 901 of the insulating portions 900, 900’ of the two high voltage connectors 700, 700’ is forced away from the connecting surfaces 901, 901’ by means of the mechanical force applied. The flow channels 820, 830 shown in Fig. 3b are formed by mechanically joining the first and second high voltage connectors so that the respective recesses 810, 810’ and 811, 811’ forms a respective flow channel 820, 830 that extend from the respective first interior point to the respective second exterior point.

Fig. 4a shows two high voltage connectors 700, 700’ each comprising an insulating portion 900, 900’ and a high voltage electrode portion 902, 902’ for carrying high voltage electric pulses where electrically insulating material 800 has been applied on the connecting surfaces 901 of the insulating portion of a first high voltage connector 700 prior to connecting the first high voltage connector 700 to a second high voltage connector 700’. The second high voltage connector 700’ in Fig. 4a comprises two flow channels 820, 830 each configured to be used for forcing away applied electrically insulating material 800 to thereby force away air present at the connecting surfaces 901, 901’ of the insulating portions 900, 901 of the two high voltage connectors 700, 700’. Each of the two flow channels 820, 830 extends from their respective first interior point to their respective second exterior point.

Fig. 4b illustrates when the first high voltage connector 700 of Fig. 4a is about to be mechanically connected to the second high voltage connector 700’. The connecting surfaces 901, 901’ of the insulating portions 900, 900’ of the first and second high voltage connectors are about to be joined together. When the connecting surfaces 901, 901’ of the insulating portions 90, 900’ of the first high voltage connector 700 and the second high voltage connector 700’ are joined together, i.e., mechanically connected, electrically insulating material 800 applied on the connecting surfaces 901 of the insulating portions of the first high voltage connector 700, and thereby also gas such as air trapped between the connecting surfaces of the insulator connection, is forced away from the insulator connection by means of the applied mechanical force in that applied electrically insulating material 800 is allowed to pass through the two flow channels 820, 830 of the second high voltage connector 700’.

Fig. 5 shows two high voltage connectors 700, 700’ in the form of two high voltage multi-connectors 700, 700’ each comprising an insulating portion 900, 900’ and a high voltage electrode portion 902, 902’ for carrying high voltage electric pulses where electrically insulating material 800 has been applied on the connecting surfaces 901 of the insulating portion 900 of a first high voltage multi- connector 700 prior to connecting the first high voltage multi- connector 700 to a second high voltage multi- connector 700’. The second high voltage multi-connector 700’ comprises two flow channels 820, 830 each configured for forcing away applied electrically insulating material 800 to thereby also force away gas such as air present at the connecting surfaces 901, 901’ of the insulating portions 900, 900’ of the two high voltage multi-connectors 700, 700’ when the first high voltage multiconnector 700 is mechanically and electrically connected to the second high voltage multi-connector 700’. Each of the two flow channels 820, 830 in Fig. 5 extends from their respective first interior point to a common flow path 840 located between the first high voltage multi-connector 700 and the second high voltage multi-connector 700’.

An example method 600 for mechanically and electrically connecting a first high voltage connector to a second high voltage connector by means of the example embodiments of a pulsed power drilling system shown in Fig. 2 is illustrated in Fig. 6. The method comprises the following actions/ steps:

610: Applying, by the applicator device and under the control of the processing circuitry of the control system, electrically insulating material on at least portions of the connecting surfaces of an insulating portion of a first high voltage connector;

620: Connecting, mechanically and electrically, the first high voltage connector to a second high voltage connector to form a high voltage conductor joint;

630: Generating, by the pulsed power generator, a high voltage electric pulse; and

640: Passing the generated high voltage electric pulse via the high voltage conductor joint.

Fig. 7 illustrates schematically a drill rig 500, or rock drilling machine, comprising a pulsed power drilling system 100 as shown in Fig. 2, drilling a hole 401 in a mineral substrate 400 in the form of a rock. The drill rig 500 comprises the alternating current (AC) power supply 113 for powering the pulsed power generator 110. It further comprises a compressed gas supply system 130 and a fluid supply system 140. A hydraulic, pneumatic, or electrically actuated arm 510 for at least vertical positioning of the drilling tool 100 is provided, such as in response to signals from one or more position sensors (not shown) or similar sensing the distance between the electrodes and the mineral substrate surface. The drill rig 500 further comprises ground engaging members 520 for moving the drill rig 500 in a direction parallel with the rock 400.

It is to be understood that the present disclosure is not limited to the embodiments described above and illustrated in the drawings; rather, the skilled person will recognize that many changes and modifications may be made within the scope of the appended claims.

Claims

1. A pulsed power drilling system ( 100) comprising a pulsed power generator (110) for generating high voltage electric pulses, a feed device (700”) comprising of an insulating portion and a high voltage electrode portion that is electrically connectable to the pulsed power generator (110), and a drill rod handling device (305) for gripping and moving high voltage connectors in the form of drill rods (700, 700’), the pulsed power drilling system (100) further comprises a control system (160) including processing circuitry and:

- an applicator device (302) configured to apply, under the control of the processing circuitry of the control system, electrically insulating material (800) on at least portions of the connecting surfaces (901, 901’) of an insulating portion (900, 900’) of a high voltage connector (700, 700’, 700”) that further comprises a high voltage electrode portion (902, 902’) for carrying high voltage electric pulses (150) generated by the pulsed power generator (100).

2. The pulsed power drilling system (100) according to claim 1, wherein the pulsed power drilling system (100) comprises an arrangement for moving the applicator device (304) and bring the applicator device (302) in position for applying the electrically insulating material (800) on connecting surfaces of (901, 901’) the insulating portion (900, 900’) of the high voltage connector (700, 700’, 700”).

3. The pulsed power drilling system (100) according to any of claims 1 and 2, wherein the drill rod handling device (305) is configured to grip and move a high voltage connector in the form of a drill rod (700, 700”) so that the connecting surfaces (901, 901’) of the drill rod (700, 700’) is positioned to be aligned with corresponding connecting surfaces of another high voltage connector (700, 700’, 700”), and wherein the processing circuitry of the control system (160) is configured to control the applicator device (302) so that electrically insulating material (800) is applied on connecting surfaces (901, 901’) of the insulating portion (900, 900’) of at least one of said drill rod (700, 700’) and another high voltage connector (700, 700’, 700”) during a portion of a time period when the connecting surfaces (901, 901’) of the drill rod (700, 700’) are positioned to be aligned with corresponding connecting surfaces (901, 901’) of the other high voltage connector (700, 700’, 700”) and before the drill rod (700, 700’) is mechanically and electrically connected to the other high voltage connector (700, 700’, 700”) to form a high voltage connector joint.

4. The pulsed power drilling system (100) according to any of claims 1 to 3, wherein the arrangement for moving the applicator device (304) is configured to bring the applicator device (302) in at least one position for applying the electrically insulating material on at least portions of the connecting surfaces (901, 901 j of the insulating portion (900, 900 j of at least one of a first high voltage connector in the form of the feed device (700”) and a second high voltage connector in the form of a drill rod (700, 700 j.

5. The pulsed power drilling system (100) according to any of the preceding claims, wherein the drill rod handling device (305) is configured to grip a drill rod (700, 700j and position the drill rod (700, 700j to be aligned with the feed device (700”), and wherein the processing circuitry of the control system (160) is configured to control the drill rod handling device (305) and the applicator device (302) so that the applicator device (320) applies the electrically insulating material (800) on exposed connecting surfaces (901, 901 j of the insulating portion (900, 900j of the drill rod (700, 700j after the drill rod (700, 700 j is aligned with the feed device (700”) and before the drill rod (700, 700j is mechanically and electrically connected to the feed device (700”) to form a high voltage connector joint.

6. The pulsed power drilling system (100) according to any of the preceding claims, wherein the feed device (700”) is a high voltage connector that comprises a recess (800, 810) or channel configured to form a flow path channel (820, 830) that extends from a first interior point to a second exterior point of a high voltage connection when the feed device (700”) is mechanically and electrically connected with another high voltage connector in the form of a drill rod (700, 700 j to form a high voltage connector joint, so as to allow for electrically insulating material (800) present on at least a portion of the connecting surfaces (901, 901 j of at least one of two opposite insulating portions (900, 900 j to flow from the first interior point to the second exterior point by means of the mechanical force applied when mechanically connecting the feed device (700”) with the drill rod (700, 700’).

7. The pulsed power drilling system (100) according to any of the preceding claims, wherein the system (100) further comprises a cleaning device (301) configured for cleaning the connecting surfaces of an insulating portion (901, 901’) of a high voltage connector in the form of a drill rod (700, 700) prior to applying, by the applicator device (302), electrically insulating material (800) on the connecting surfaces (901, 901’) of the drill rod (700, 700’).

8. The pulsed power drilling system (100) according to any of the preceding claims, wherein the pulsed power drilling system (100) further comprises an arrangement for moving the cleaning device (305) to bring the cleaning device (301) in position for cleaning the connecting surfaces (901, 901’) of an insulating portion (900, 900’) of at least one of the feed device (700”) and a drill rod (700, 700’) prior to applying, by the applicator device (302), electrically insulating material (800) on the connecting surfaces (901, 901’) of the insulating portion (900, 900’) of at least one of the feed device (700”) and a drill rod (700, 700’) to be mechanically and electrically connected to the feed device (700”) to form a high voltage connector joint.

9. The pulsed power drilling system (100) according to any of claims 7 and 8, wherein the processing circuitry of the control system (160) is configured to control the arrangement for moving the cleaning device (305) so that the cleaning device (301) is in position for cleaning connecting surfaces (901, 901 j of the insulating portion of at least one of the feed device (700”) and a high voltage connector in the form of a drill rod (700, 700 j to be connected to the feed device (700 ”) during a portion of a time period after the feed device (700”) has been mechanically and electrically disconnected from a high voltage connector in the form of another drill rod (700, 700 j and before applying, by the applicator device (302), electrically insulating material (800) on the connecting surfaces (901, 901 j of the insulating portion (900, 900 j of at least one of the feed device (700”) and said drill rod (700, 700j to be connected to the feed device (700”).

10. The pulsed power drilling system (100) according to any of claims 7 to 9, wherein the cleaning device (301) comprises at least one of a nozzle (303, 303’) for spraying a compressed gas on a connecting surface (901, 901’) of an insulating portion (900, 900’), a mechanical brush (301) for cleaning a connecting surface (901, 901’) of an insulating portion (900, 900’) and an applicator (301) for applying a cleaning agent onto a connecting surface (901, 901’) of an insulating portion (900, 900’).

11. The pulsed power drilling system ( 100) according to any of the preceding claims, wherein the applicator device (302) is configured to apply electrically insulating material (800) in the form of at least one of grease and a lubricant composition.

12. A method (600) for mechanically and electrically connecting a first high voltage connector to a second high voltage connector (700, 700’, 700”) in a pulsed power drilling system (100) comprising a control system (160) including processing circuitry, a pulsed power generator (110) for generating high voltage electric pulses, a feed device (700”) comprising of an insulating portion (900, 900’) and a high voltage electrode portion (902, 902’) that is electrically connectable to the pulsed power generator (110), and a drill rod handling device (305) for gripping and moving high voltage connectors in the form of drill rods (700, 700’), the pulsed power drilling system further comprises an applicator device (302) configured to apply electrically insulating material (800), the method (600) comprising:

Applying (610), by the applicator device (302) and under the control of the processing circuitry of the control system ( 160) , electrically insulating material (800) on at least portions of the connecting surfaces (901, 901’) of an insulating portion (900, 900’) of a first high voltage connector (700, 700’, 700”) that further comprises a high voltage electrode portion (902, 902 ’) for carrying high voltage electric pulses ( 150) , wherein the electrically insulating material (800) is applied during a portion of a time period when an open end of said first high voltage connector (700, 700’, 700”) comprising said connecting surfaces (901, 901’) of the insulating portion (900, 900’) is electrically and mechanically disconnected from other high voltage connectors (700, 700’, 700”), mechanically and electrically connecting said first high voltage connector (700, 700’, 700”) to a second high voltage connector (700, 700’, 700”), wherein the applied electrically insulating material (800) is present on the connecting surfaces (901, 901’) of the insulating portion (900, 900’) of said first high voltage connector (700, 700’, 700”) when mechanically and electrically connecting said first high voltage connector (700, 700’, 700”) to said second high voltage connector (700, 700’, 700”) to form a high voltage connector joint, generating, by the pulsed power generator (110), a high voltage electric pulse (150), and passing the generated high voltage electric pulse ( 150) via the high voltage connector joint.

13. The method (600) according to claim 12, wherein the system (100) further comprises an arrangement for moving the applicator device (305), the method (600) further comprising: moving, by means of the arrangement for moving the applicator device (305), the applicator device (302) in position for applying electrically insulating material (800) on the at least portions of the connecting surfaces (901, 901 j of the insulating portion (900, 900 j of the first high voltage connector (700, 700’, 700”), wherein the applicator device (302) is thereby brought in position prior to applying the electrically insulating material (800).

14. The method (600) according to any of claims 12 and 13, wherein the system (100) further comprises an arrangement (300) including a cleaning device (301), the method (600) further comprising: cleaning, by means of the cleaning device (301), said connecting surfaces (901, 901 j of the insulating portion (900, 900 j of the high voltage connector (700, 700’, 700”) prior to said step of applying electrically insulating material (800) on the at least portions of said connecting surfaces (901, 901 j of the insulating portion (900, 900 j of said first high voltage connector (700, 700’, 700”).

15. The method (600) according to claim 14, the system (100) further comprises an arrangement for moving the cleaning device (305), the method (600) further comprising:

- moving, by means of the arrangement for moving the cleaning device (305), the cleaning device (301) in position for cleaning the connecting surfaces (901, 901’) of the insulating portion (900, 900’) of the first high voltage connector (700, 700’, 700”), wherein the cleaning device (301) is thereby brought in position for cleaning the connecting surfaces (901, 901’) prior to applying the electrically insulating material (800).

16. The method (600) according to any of claims 12 to 15, wherein said first high voltage connector is the feed device (700”) and said second high voltage connector is a drill rod (700, 700’), wherein at least one of the feed device (700”) and said drill rod (700, 700’) comprises a recess (810, 810’, 811, 811’) or channel (820, 830) configured to form a flow path channel (820, 830) that extends from a first interior point to a second exterior point of a high voltage connection when the feed device (700”) is mechanically connected with another high voltage connector in the form of a drill rod (700, 700’) to form a high voltage connector joint, the method (600) further comprising:

- passing, by means of the mechanical force applied when mechanically connecting the first high voltage connector in the form of the feed device (700”) with the second high voltage connector in the form of a drill rod (700, 700 j, at least a portion of the applied electrically insulating material (800) through portions of said flow path channel (820, 830) to thereby force away gas present on or close to said connecting surfaces (901, 901 j of the insulating connection formed when connecting the connecting surfaces (901, 901 j of the insulating portion (900, 900j of the feed device (700”) to corresponding connecting surfaces (901, 901 j of the insulating portion (900, 900 j of the drill rod (700, 700 j.

17. The method (600) according to any of claims 12 to 16, wherein said step of applying includes applying the electrically insulating material (800) on the connecting surfaces (901, 901 j of an insulating portion (900, 900 j of a high voltage connector in the form of a drill rod (700, 700 j that comprises a recess (810, 810’, 811, 81 Ij or channel (820, 830) configured to form a flow path channel (820, 830) that extends from a first interior point to a second exterior point of a high voltage connection when the drill rod (700, 700’) is mechanically connected with another high voltage connector (700, 700’, 700”) to form a high voltage connector joint, the method (600) further comprising:

- positioning, by means of the drill rod handling device (305) for gripping and moving high voltage connectors in the form of drill rods (700, 700 j, the drill rod (700, 700j so that the drill rod (700, 700j is aligned with another high voltage connector (700, 700’, 700”), and

- passing, by means of the mechanical force applied when mechanically connecting the drill rod (700, 700 j with the other high voltage connector (700, 700’, 700”), at least a portion of the applied electrically insulating material (800) through at least portions of said flow path channel (820, 830) to thereby force away gas present on or close to said connecting surfaces (901, 901 j of the insulating connection formed when connecting the connecting surfaces (901, 901 j of the insulating portion (900, 900 j of the drill rod (700, 700j to corresponding connecting surfaces (901, 901 j of the insulating portion (900, 900 j of the other high voltage connector (700, 700’, 700”).

18. The method (600) according to any of claims 12 to 17, the feed device (700”) further comprises a detector for detecting whether gas is present in an insulating connection between the feed device (700”) and a high voltage connector in the form of a drill rod (700, 700j, the method (600) comprising: obtaining, by use of the detector, sensor data indicating whether gas is present in an insulating connection of a high voltage connector joint including said feed device (700”) and a first drill rod (700, 700j, and determining, by the processing circuitry of the control system (160), whether gas is present in the insulating connection of the high voltage connector joint involving said feed device (700”) and the first drill rod (700, 700j.

19. The method (600) according to claim 18, wherein upon determining that gas is present in the insulating connection of the high voltage connector joint including said feed device (700”) and the first drill rod (700, 700j, the method (600) is further comprising: disconnecting said feed device (700”) from the first drill rod (700, 700’), and applying electrically insulating material (800) to the connecting surfaces (901, 910’) of the insulating portion (900, 900’) of at least one of said feed device (700”) and a second high voltage connector in the form of a new drill rod (700, 700’) to be connected to the feed device (700”).

20. A drill rig (500) comprising a pulsed power drilling system (100) according to any one of claims 1- 11 for breaking of a mineral substrate, such as in any one of rock drilling, concrete processing, mineral processing, material fragmentation and continuous mining.