Classifications

• • G—PHYSICS
  • G01—MEASURING; TESTING
  • G01R—MEASURING ELECTRIC VARIABLES; MEASURING MAGNETIC VARIABLES
  • G01R19/00—Arrangements for measuring currents or voltages or for indicating presence or sign thereof
  • G01R19/0084—Arrangements for measuring currents or voltages or for indicating presence or sign thereof measuring voltage only
• • G—PHYSICS
  • G01—MEASURING; TESTING
  • G01R—MEASURING ELECTRIC VARIABLES; MEASURING MAGNETIC VARIABLES
  • G01R15/00—Details of measuring arrangements of the types provided for in groups G01R17/00 - G01R29/00, G01R33/00 - G01R33/26 or G01R35/00
  • G01R15/14—Adaptations providing voltage or current isolation, e.g. for high-voltage or high-current networks
  • G01R15/16—Adaptations providing voltage or current isolation, e.g. for high-voltage or high-current networks using capacitive devices

Definitions

• the invention relates to a voltage sensor for powerline and/or cable accessories applications.
• Useful sensing may include, for example, voltage, current, and the time relationship between voltage and current at various locations within a power distribution network.
• a voltage sensor that can be connected to a power line, cable, or cable accessories.
• a voltage sensor comprises a conductor having a first end and a second end, the first end including a first connection interface and the second end having no connection, and a sensor section including at least one sensor disposed over the conductor between the first and second ends, the sensor sensing at least a voltage or a sample of the voltage of the conductor.
• the second end has reduced electric field stress concentration.
• the second end of the conductor has a rounded surface, such as a fully rounded (or semi- hemispherical) surface.
• the second end includes a bulbous rounded surface.
• the sensor section includes a voltage sensor.
• a first electrode of the voltage sensor can comprise the conductor.
• the first electrode of the voltage sensor comprises an inner shield layer in contact with the conductor.
• the voltage sensor further includes an insulation layer disposed over the isolated inner shield layer, and an electrically isolated outer shield layer disposed over the insulation layer.
• Fig. 1 is a cut away view of a voltage sensor according to an aspect of the present invention.
• Fig. 2 is a close-up section view of the sensing section of the voltage sensor according to another aspect of the present invention.
• Fig. 3 is a close-up, cross section view of the voltage sensor according to another aspect of the present invention.
• the present disclosure describes a voltage sensor that can be used, for example, to measure the voltage of a power line, such as an overhead power line, at a particular location, such as a capacitor bank, switch or protective device, such as an overhead switch (manual or actuated by a motor, solenoid, etc.), a sectionalizer or recloser, or a voltage regulation
• the voltage sensor utilizes an integrated, high accuracy capacitive voltage sensor.
• the voltage sensor can have a compact design and can be coupled to an existing power line (conductor or cable) in a straightforward manner.
• the voltage sensor described herein can provide a compact mechanism for providing real time, high accuracy voltage characteristics of a power cable or location in an electrical grid.
• the output of the voltage sensor can be a waveform that is directly proportional to the voltage of the power line.
• the division ratio of the actual line voltage to the output voltage can be tailored to any desired voltage.
• the division ratio can be between 1 : 1 and 1,000,000: 1; in other preferred embodiments, the division ratio can be approximately 10,000: 1, where for example an actual line voltage of approximately 10,000 Volts would result in an output voltage of approximately 1 Volt.
• the voltage sensor supplies a voltage level that can in some embodiments be easily converted to a digital value for interaction with computational devices,
• the voltage sensor can thus provide a utility, solar farm, wind farm, ship, industrial plant, or any individual or company that uses medium or high voltage equipment with an easy access to obtain a real time voltage reading of a live power line, as well as the ability to create a smart node at many different grid locations.
• FIG. 1 shows a first aspect of the invention, voltage sensor 100.
• Voltage sensor 100 includes a conductor (also referred to as an inner conductor) 102, which may be a solid or stranded metal axial conductor such as an aluminum or copper alloy conductor.
• Inner conductor 102 includes a first end 101, which can include a first connection interface 150 and a second end 103.
• the second end 103 has no connection.
• the second end is shaped to allow for optimal stress control in a minimal space with ease, to substantially reduce the probability of partial discharge or electrical failure.
• second end 103 includes a rounded surface 105, such as a fully rounded surface (i.e., having no or almost no sharp edges). This rounded surface shape reduces electric field stress
• the rounded surface 105 has a bulbous shape.
• a bulbous end can be omitted.
• a full radius can be formed from the end 103 of the conductor. This semi- hemispherical shape would also remove any sharp edges that can lead to electric stress concentrations.
• the second end 103 of the voltage sensor 100 can be covered with a molded semiconducting rubber or semiconducting plastic material.
• the semiconducting molding can be used to cover a rounded surface or a sharp surface.
• the first connection interface 150 can include a lug, which is shown in Fig. 1.
• connection interface can comprise a separable connector, a splice, a modular connector, or other connection interfaces.
• connection interface can have a circular cross section configured to mate to a male end of conductor 102.
• first end of the conductor 102 can be formed as a male or hybrid type connector.
• connection interface 150 comprises a lug.
• the structure of Fig. 1 allows for straightforward mechanical fastening and electrical conduction (or path) from an overhead power cable or line.
• one method of attaching the voltage sensor 100 to an overhead line is to use a conventional overhead primary tap (such as a BUF/AHF two hole hot line pad connector available from Hubbell Power Systems, USA) and bolt that connector to connection interface/lug 150.
• a conventional stem connector can be used.
• voltage sensor 100 can be installed at any point along a power cable, line or in a cable accessory.
• voltage sensor 100 is configured to control the electrical field created by medium or high voltage within a power line or cable, such as an overhead power line or cable, wherein the power line or cable operates at voltages in excess of 1,000 Volts.
• a high K layer 132 can be employed to control the electric field.
• voltage sensor 100 can include geometric stress control (not shown).
• inner conductor 102 may be radially surrounded by conductor shield layer 104.
• Conductor shield layer 104 comprises a conductive or semi- conductive material that is configured to smooth out any conductor surface inconsistencies that could create high electric field stress concentrations, especially when sensing the voltage of a medium or high voltage line or cable, which could cause a reduction in accuracy or possible sensor failure.
• the outer surface of the conductor shield layer 104 is smooth.
• the inner conductor 102 and optional inner shield layer 104 provide one electrode of a capacitor for the sensor section. The other electrode of the capacitor is formed by the isolated section 110 of insulation shield layer 108, and insulation layer(s) 106 serves as the dielectric of the capacitor.
• Voltage sensor 100 further includes insulation layer 106, which concentrically surrounds conductor shield layer 104.
• the insulation layer 106 can be formed from a conventional dielectric material, such as elastomeric silicone, ethylene propylene diene monomer rubber (EPDM), hybrids or combinations thereof.
• insulation layer 106 can comprise more than 1 layer of insulation material, such as first and second insulation layers (not shown), with each layer being formed from a different or same insulation material.
• the optional semi- conductive or conductive shield layer 104 functions to eliminate or reduce the potential for voids between conductor 102 and insulation layer(s) 106 that might allow leakage leading to degradation of insulation layer(s) 106.
• Shield layer 104 may also relieve electrical stresses caused by any roughness on the surface of the inner conductor 102 due to, for example, manufacturing processes such as casting.
• conductive layer 102 can have a highly smooth outer surface.
• an adhesive or other bonding material can be interposed between the conductive layer 102 and the insulation layer 106, with the shield layer 104 being omitted.
• the adhesive or other bonding material can be applied to the outer surface of conductor 102 and can bond the insulation layer 106 to the conductive layer 102.
• an insulation shield layer 108 is provided and concentrically surrounds insulation layer 106.
• the insulation shield layer 108 comprises a conductive or semi conductive material formed as a layer adjacent to and concentrically surrounding insulation layer 106.
• this insulation layer 106 also forms the insulation layer of a capacitor, which also comprises the inner conductor 102 and/or conductor shield layer 104 and isolated section 110 of insulation shield layer 108. Isolated section of insulation shield layer 110 is isolated from the ground potential of the remainder of insulation shield layer 108.
• voltage sensor 100 further comprises a tubular sleeve 112 that extends over at least a portion of the conductor/inner shield/insulation/shield structure and the sensor section 125.
• tubular sleeve 112 comprises a suitable cold-shrinkable material, such as a highly elastic rubber material that has a low permanent set, such as EPDM, elastomeric silicone, electrical grade resin, or a hybrid thereof.
• Insulation layer 106 and tubular sleeve can be made of the same or different types of materials.
• the semi-conductive and insulating materials may have differing degrees of conductivity and insulation based on the inherent properties of the materials used or based on additives added to the materials.
• Tubular sleeve 112 may also be made from a suitable heat-shrinkable material. Alternatively, the tubular sleeve 112 may be an overmolded or push-on layer. A ground reference wire 115 can also be provided. Optionally, in the illustrated embodiment, tubular sleeve 112 includes skirts 135 which serve to reduce leakage current and which is particularly useful for outdoor applications. In some embodiments, tubular sleeve 112 can also cover rounded end 103.
• a sealing compound 130 can be provided to create an environmental seal and prevent moisture from migrating into the area between the insulation layer 106 and the connection interface/lug 150.
• voltage sensor 100 includes a sensor section 125 disposed between the first and second ends of conductor 102.
• the sensing section includes a voltage sensor, such as an impedance voltage divider that utilizes complex impedance based voltage division, or a capacitive voltage sensing device, having an electrically isolated capacitive voltage sensor. More generally, in at least one aspect, where the sensing section includes an impedance voltage divider, a first impedance and a second impedance are connected in series. The input voltage is applied across the series impedances and the output voltage is the voltage across the second impedance.
• the first and second impedances may be composed of any combination of elements such as resistors, inductors and capacitors.
• the sensing section includes a multi-component AC circuit, wherein the response can be complex and can have imaginary components.
• the sensor section includes at least one temperature compensation component, such as, e.g., a thermistor.
• the temperature sensor e.g., thermistor
• the voltage sensor 100 can further include one or more additional sensors.
• the sensing section 125 includes an electrically isolated section 110 of conductive or semiconductive material (insulation shield) layer 108 in contact with an outer surface of insulation layer 106.
• the electrically isolated section 110 of conductive or semiconductive material (insulation shield) layer 108 in contact with an outer surface of insulation layer 106.
• semiconductive material (insulation shield) layer 108 forms an electrode of a sensing capacitor of a capacitive voltage divider or sensor.
• the electrically isolated section thus can be
• insulation layer 106 is operable to form a dielectric of the sensing capacitor of the capacitive voltage divider or sensor.
• the electrically isolated section 110 may be in an annular ring configuration and be electrically isolated from conductive or semiconductive shielding layer 108 by non-conductive axial sections 111a and 11 lb.
• Non-conductive axial sections 111a, 11 lb may comprise non-conductive material or a void.
• conductive or semiconductive shielding layer 108 may be
• electrically isolated section 110 may be formed out of a common material and manufacturing process, such that electrically isolated section 110 and shield layer 108 have a common thickness.
• electrically isolated section 110 may be formed from a different material than shield layer 108 and/or have a different configuration such as a rectangular or round shape formed by a flexible material affixed to insulation layer 106. Electrically isolated section 110 may, for example, comprise an electrically conductive metal or an electrically conductive polymer. As one example, electrically isolated section 110 may comprise a layer of copper. In some examples, voltage sensor 100 may include an adhesive that affixes electrically isolated section 110 to insulation layer 106. In some examples, electrically isolated section 110 may further include a conforming rubber insulation or high dielectric constant tape or a self- fusing insulation or high K material 127, such as a rubber mastic material, to prevent moisture from migrating into the sensor section 125.
• strips of insulating or high dielectric constant material cover gaps 111a, 11 lb to separate isolated section 110 from any other conductive or semi conductive material or elements, except from the PCB 120, and to prevent the presence of air in gaps 111a, 11 lb, which air could cause a partial electrical discharge and a failure of the voltage sensor.
• the insulating or high dielectric constant material may be any suitable material such as a combination of mastic, which will more easily fill gaps 111a, 11 lb, and PVC tape placed over the mastic.
• the electrically isolated section 110 may include a heat shrinkable or cold shrinkable material.
• inner and outer conductive or semi conductive shield layers 104, 108 and insulating layer 106 of voltage sensor 100 may be made from any materials suitable for shrinkable sleeve applications. Most suitable are materials such as a highly elastic rubber material that has a low permanent set, such as ethylene propylene diene monomer (EPDM), elastomeric silicone, or a hybrid thereof, that may include conventional additives to make the layers appropriately conductive, semi conductive or insulating, as needed.
• the conductive or semi conductive shield layers and the insulation layer may be made of the same or different types of materials, depending on the types of additives which may be incorporated in the individual layers.
• the inner and outer conductive or semi conductive shield layers and the insulation layer may have differing degrees of conductivity and insulation based on the inherent properties of the materials used or based on additives added to the materials.
• the sensor section 125 is configured as a capacitive voltage sensor, which is operable to sense a voltage on inner conductor 102, which is also representative of the voltage on the power line (not shown) by way of the connection with the connection interface 150.
• Electrically isolated section 110 is operable to form an electrode of the sensing capacitor of the capacitive voltage sensor and may, for example, have two opposed major surfaces, e.g. first and second major surfaces.
• the first major surface may be in mechanical contact with insulation layer 106.
• the second major surface may be in mechanical contact with a capacitive element, such as a capacitor, circuitry, or a printed circuit board (PCB) 120.
• the capacitive element, such as PCB 120 has a pre-defined capacitance value.
• the output of the voltage sensor can be a waveform that is directly proportional to the voltage of the power line.
• the division ratio of the actual line voltage to the output voltage can be tailored to any desired voltage. In some embodiments, the division ratio can be between 1 : 1 and 1,000,000: 1; in other aspects, the division ratio can be approximately 10,000: 1, where for example an actual line voltage of approximately 10,000 Volts would result in an output voltage of approximately 1 Volt.
• the voltage sensor 100 supplies a voltage level that can in some embodiments be easily converted to a digital value for interaction with computational devices, microcontrollers, communication devices, etc.
• the capacitive voltage sensor further includes capacitive element (here PCB 120), which is in electrical contact with electrically isolated section 110.
• the PCB 120 is located close to or directly over the electrically isolated section 110 to arrange for the electrical contact with the isolated section 110, which in turn is arranged on insulation layer 106.
• PCB 120 further includes at least one additional capacitor or other capacitive element to form a capacitive voltage divider for determining the voltage of inner conductor 102 by way of the detected voltage of electrically isolated section 110.
• the capacitor(s) of PCB 120 may be electrically connected to electrically isolated section 110.
• the capacitive element may be operable as a secondary capacitor in a capacitive voltage divider.
• the capacitive voltage divider may comprise the sensing capacitor, which includes electrically isolated section 110, and the secondary capacitor.
• PCB 120 may be flexible such that PCB 120 may be bent to conform around electrically isolated section 110.
• PCB 120 may establish electrical contact to electrically isolated section 110 in several locations. This construction avoids the disadvantages of having electrical contact only in one location on electrically isolated section 110, such as, problems resulting from a bad electrical contact in the one location, if that one contact is, e.g., incomplete, corroded, or damaged, which might preclude a voltage reading.
• providing multiple points of contact may avoids problems arising from the fact that electrons travelling from a rim of electrically isolated section 110 to a single contact location experience the electrical resistance of electrically isolated section 110 over a longer path. This, in turn, may lead to a voltage drop and eventually to a lower, i.e. less accurate, voltage being measured on PCB 120.
• PCB 120 may be mechanically attached to electrically isolated section 110. In other examples, PCB 120 may alternatively be in a pressure contact with electrically isolated section 110.
• PCB 120 may comprise a double-sided PCB, i.e. PCB 120 can have opposed first and second major sides. Alternatively the PCB 120 can be located remotely from the isolated section 110, where the PCB 120 can be electrically coupled to the isolated section 110.
• PCB 120 can comprise a multilayer structure, with a first layer 120a comprising a conductive metal, e.g. gold, silver, or copper; a second layer 120b comprising a flexible insulation material; a third layer or conductive trace 120c to connect to jumper wires 122; a fourth layer 120d comprising an outer insulation layer; and an outer conductive shield layer 120e comprising a conductive or semiconductive layer which shields PCB 120.
• a conductive metal e.g. gold, silver, or copper
• second layer 120b comprising a flexible insulation material
• a third layer or conductive trace 120c to connect to jumper wires 122
• fourth layer 120d comprising an outer insulation layer
• an outer conductive shield layer 120e comprising a conductive or semiconductive layer which shields PCB 120.
• the first layer 120a can comprise a copper layer that may be gold-plated for enhanced electrical contact and/or for protection against environmental influences, e.g.
• first PCB layer 120a comprises a conductive region that provides a continuous surface contact area or a patterned, i.e. interrupted, non-continuous, surface contact area for contact with electrically isolated section 110. All parts of the patterned surface contact area may be electrically connected with each other. A patterned surface contact area may require less conductive material for manufacturing it, while having only a negligible influence on reliability of the electrical contact and resistive losses.
• PCB 120 may comprise a flexible portion.
• a patterned surface contact area may also enhance the mechanical flexibility of PCB 120, thus reducing the risk of layer cracking and/or flaking, when PCB 120 is bent.
• the first PCB layer 120a comprises a patterned gold-plated copper layer.
• a pattern of the surface contact area may, for example, be a grid with a square-shaped or a diamond-shaped pattern.
• the PCB 120 may further comprise a second layer 120b comprising a flexible insulating material, such as a conventional, flexible insulation material.
• a flexible portion of PCB 120 and in particular a flexible PCB may allow PCB 120 to conform better to electrically isolated section 110. This, in turn, enhances the electrical contact between PCB 120 and electrically isolated section 110 and thereby makes the contact more reliable, reduces resistive losses, and facilitates higher accuracy of the voltage sensor.
• a conductive trace 120c connects with jumper wires 122, which are connected to ground on either side of the isolated section 110 by conductive tape/adhesive 109 disposed on shield layer 108.
• the conductive tape/adhesive 109 provides adequate surface area.
• the outer shield layer 120e can comprise a conductive or semiconductive material and is grounded to conductive tape/adhesive 109, as shown in Fig. 3.
• PCB 120 may further include a plurality of ratio adjustment capacitors.
• PCB 120 may generate a signal that is indicative of the voltage of inner conductor 102.
• Sensor signal wire 124 can be connected to PCB 120 for transmitting the sensor voltage signal from PCB 120.
• electrical measurement circuitry may be incorporated into the PCB 120; in other examples, PCB 120 may include electrical measurement circuitry.
• Sensor signal wire 124 they may be connected to, for example, a remote terminal unit that processes voltage data from the sensor section 125, or an integrator, a measuring device, a control device, or other suitable types of devices.
• a ground reference wire 122 may be used to bring ground onto PCB 120 for connecting electrical ground to the electrical measurement circuitry.
• ground reference wire 122 is connected to a conductive trace of PCB 120, such as conductive trace 120c shown in Fig. 3. This configuration brings a bridging connection between the insulation shield layers on either side of isolated section 110.
• the electric measurement circuitry may be operational to determine the voltage of inner conductor 102 versus ground.
• PCB 120 may be adapted to support additional sensing such as temperature, humidity, magnetic field, etc.
• PCB 120 can be directly disposed on insulation layer 106, such that the isolated section 110 of the shielding layer 108 can be eliminated. In a further alternative aspect, PCB 120 can be disposed directly on insulation layer 106 at a position beyond an end of the shielding layer 108.
• the sensor section 125 further includes a sensor insulation layer 126 that is disposed adjacent to the isolated section 110.
• the sensor insulation layer 126 can be adjacent to the PCB 120 and on the opposing side of PCB 120 relative to electrically isolated section 110. The sensor insulation layer 126 helps to prevent the PCB 120 from shorting out.
• the sensor section 125 further includes a sensor (outer) shielding layer 128 that is disposed adjacent to sensor insulation layer 126 on the opposing side of sensor insulation layer 126 relative to PCB 120.
• Outer sensor shield layer 128 may be formed from a conductive or semiconductive material and may be electrically connected to shield layer 108, e.g., at ground potential.
• Outer sensor shield layer 128 provides electric field shielding to contain the electric field from the isolated section 110/outer electrode and from external electric fields.
• Outer sensor shield layer 128 and insulation shield layer 108 may function to
• outer sensor shield layer 128 and insulation shield layer 108 may be formed as a unitary feature.
• tubular sleeve 112 extends over at least a portion of the sensor section 125.
• the precise dimensional control facilitated by the design and configuration of voltage sensor 100 allows for precise voltage measurements by the capacitive voltage sensor of the sensor section 125.
• capacitance is directly related to the geometry of two conductive electrodes and the insulation forming the capacitor.
• the sensing capacitor is formed from inner conductor 102/inner shield layer 104, insulation layer 106 and electrically isolated section 110.
• voltage sensor 100 may be formed using overmolded construction.
• inner shield layer 104 may be overmolded on inner conductor 102.
• insulation layer 106 may be an overmolded insulation layer overmolded on inner shield layer 104 or overmolded directly on inner conductor 102 if inner shield layer 104 is not included in the voltage sensor device 100.
• shield layer 108 may be an overmolded outer conductive or semi conductive layer overmolded on insulation layer 106.
• the construction can comprise a multilayer body that can be formed as a contiguous overmolded body that comprises the insulation layer 106, shield layer 108, the isolated section 110, and optionally the inner shield layer 104.
• the voltage ratio of the sensing section 125 can be adjusted by varying the length of the isolated section 110 or, in an alternative aspect, by varying the length of the PCB 120 that replaces isolated section 110.
• RTV, grease, mastic, or other insulating or high dielectric constant materials can be applied to eliminate air gaps/voids between the PCB 120 and the cable insulation 106 and/or to eliminate corona discharges.
• the voltage sensor described herein can be utilized in a variety of applications.
• the voltage sensor can be deployed on any section of the power grid having a voltage, such as with standard medium or high voltage cable, bus bars, capacitor banks, connectors, lugs, jumpers, any component used in a power grid, switches, and switch gear.
• the voltage sensor can be used in underground equipment applications such as pad mounted transclosures, pad mounted primary metering cabinets, and many live front pad mounted or vault-type live front applications.
• the voltage sensor can also be used in switch gear applications, where the gear is considered deadfront underground equipment.

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• 2016
  • 2016-05-16 BR BR112017024892A patent/BR112017024892A2/pt not_active Application Discontinuation
  • 2016-05-16 EP EP16738575.6A patent/EP3298417B1/en active Active
  • 2016-05-16 WO PCT/US2016/032630 patent/WO2016187090A1/en not_active Ceased
  • 2016-05-16 CA CA2986387A patent/CA2986387A1/en not_active Abandoned
  • 2016-05-16 US US15/573,889 patent/US10761117B2/en active Active
  • 2016-05-16 JP JP2017559801A patent/JP2018514787A/ja active Pending
  • 2016-05-16 CN CN201680028749.4A patent/CN107636477A/zh active Pending
  • 2016-05-17 TW TW105115207A patent/TW201708827A/zh unknown

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