WO2015112852A1 - Wind turbine tower elevator disconnect apparatus, assembly and method for using same - Google Patents

Abstract

An improved disconnect apparatus, assembly and method for use of such apparatus and assembly is provided for increasing the safety of workers when power to the wind tower elevator requires making or breaking the electrical connection of the elevator to its electrical supply. The apparatus, assembly and method of the present invention eliminates arc flash risk while also allowing workers to disconnect the wind tower elevator from its electrical supply without the use of special personal protective equipment. In a preferred embodiment, a fused housing is interposed between an electrical connection device and the electrical cabling to the wind turbine tower elevator and its drive motors.

Description

PATENT COOPERATION TREATY APPLICATION

SPECIFICATION

WIND TURBINE TOWER ELEVATOR DISCONNECT APPARATUS,

ASSEMBLY AND METHOD FOR USING SAME

[0001] This Application claims the benefit of U.S. Provisional Application No.

61/930,565, filed January 23, 2014.

FIELD OF THE INVENTION

[0002] The present invention relates generally to wind turbine towers and to elevators that are used in such towers for transporting workers. It also generally relates to disconnects for use with electrical devices, including disconnecting means and overcurrent protection for conductors and loads. More particularly, it relates to an improved disconnect apparatus, assembly, and the method for use of such apparatus and assembly for increasing the safety of a worker when power to the wind tower elevator requires disconnection from its electrical supply. BACKGROUND OF THE INVENTION

[0003] The use of wind turbines for converting wind energy to electrical energy is becoming more and more popular as we move toward alternative energy sources. Wind turbines of current design are typically mounted atop towers so as to place the turbines in optimal locations for receiving wind energy. Indeed, such towers are now constructed to heights of 350 feet or more. Maintenance of the wind turbine which is mounted at the top of such a tower requires that a worker manually ascend the interior of the tower structure using a ladder assembly. In areas where several wind turbine towers are located, such as on a wind turbine "farm," a worker may be required to ascend and descend several towers during a single work cycle. To prevent worker injury or death due to fatigue or other human error factors, elevators have been installed in such wind turbine towers and are well known in the art. To use such elevators, certain safety mechanisms are need to be in place and, indeed, are mandated by several worker safety laws and standards. Other standards apply to the removal, or the disconnect, of power to such elevators.

[0004] For example, the National Fire Protection Agency ("NFPA") created NFPA

70E, a Standard for Electrical Safety in the Workplace. The NFPA 70E standard was the first nationally recognized standard for electrical safety in the United States, and was the reference document used for the "Electrical Safety-Related Work Practices" regulation (OSHA 29 CFR 1910.331 through 1910.335). The first edition was released in 1976 at the request of OSHA to help provide consensus on electrical safety standards and several revisions have followed. The NFPA is also known for its sponsorship of the National Electric Code ("NEC") 2012, which requires that a fused disconnect be used on the supply side of the elevator. Use of a fused disconnect is mandated due to the potential hazard of electrical arc flashing. An electrical arc flash can be created inadvertently when high voltage connections are broken and as one electrical contact is withdrawn from a second electrical contact. During an arc flash, metal connectors are effectively vaporized, producing extremely high localized temperatures, molten metal exposure and even explosive concussive forces. The result of an arc flash can be the destruction of equipment and serious, and even fatal, injuries to workers and other personnel. [0005] In dealing with situations where the risk of arc flash exists, "hazard ratings categories" (or "HRC") are specified by NFPA 70E - depending on the risk. Among other things, the HRC is used to determine the necessary arc rating of a garment worn during a given job task. The categories range from HRC 0 (which is low risk and allows for 100% untreated cotton) up to HRC 4 (which is high risk and requires flame resistant clothing). For example, in order for a worker to service a standard disconnect of 480 volts, that worker must be dressing HRC level 0 protecting gear, per the NFPA 70E standard of 2012. The NFPA 70E standard of 2015 will require a person to be dressed in accordance with HRC level 1 protecting gear which includes arc-rated clothing with an arc rating minimum of 4 cal/cm²; an arc-related face shield; an arc-rated hard hat liner; hard hat; safety glasses; hearing protection; heavy duty leather gloves; and leather work shoes. In the experience of these inventors, the suiting up with such gear, though necessary, is time consuming and can result in exposure of the worker or workers to unnecessary arc flash risks.

[0006] Accordingly, there is a need for an improved disconnect apparatus, assembly, and the method for use of such apparatus and assembly for increasing the safety of a worker when power to the wind tower elevator requires making or breaking the electrical connection of the elevator to its electrical supply. There is also a need to provide such an apparatus, assembly and method that eliminates arc flash risk while also allowing workers to disconnect the wind tower elevator from its electrical supply without the use of special personal protective equipment. SUMMARY OF THE INVENTION

[0007] The present invention provides an improved disconnect apparatus, assembly, and a method for use of such apparatus and assembly for increasing the safety of a worker when power to the wind tower elevator requires disconnection from its electrical supply. It also eliminates the need for any of the personal protective equipment and gear mentioned above.

[0008] The foregoing and other features of the apparatus, assembly and method for using the apparatus and assembly of the present invention will be apparent from the detailed description that follows.

BRIEF DESCRIPTION OF THE DRAWINGS

[0009] FIG. 1 is a top plan view of a preferred embodiment of the apparatus that is fabricated in accordance with the present invention.

DETAILED DESCRIPTION OF THE INVENTION

[0010] The improved disconnect apparatus, assembly and the method for use of such apparatus and assembly of the present invention uses an electrical connection device that is disposed on the supply side of the apparatus and assembly. It further comprises a covered housing that includes three fuses and power cabling to the wind tower elevator and its drive motors.

[001 1] Referring to FIG. 1 , it shows the disconnect apparatus, generally identified 10. The disconnect apparatus 10 comprises an electrical connection device. The electrical connection device comprises a receptacle or socket 20 having at least one axial pressure contact arranged in insulation and at least one annular groove and a plug 30 comprising at least one tubular contact that is coaxial with the direction of coupling of the plug 30 with the socket 20. The at least one tubular contact comprises a leading end having an end surface and is structured and arranged to co-operate with the at least one axial pressure contact of the socket 20. The at least one annular groove opens out axially and is structured and arranged to receive the at least one tubular contact. At least a portion of the end face of the leading end of the at least one tubular contact presses against the at least one axial pressure contact when the at least one tubular contact is positioned in the at least one annular groove and when the plug 30 is coupled with the socket 20.

[0012] While drawing a flash arc is an inherent hazard during plug removal with traditional pin and sleeve and twist-type devices, the electrical connection device used in the present invention is configured to isolate the making, and breaking of contacts within an enclosed arc chamber. That is, the plug 30 contacts are de-energized and isolated from live parts within the enclosed arc chamber before the plug can be physically removed. The connection device includes an "off" button 22 which, when pushed, opens a spring-loaded operating mechanism which opens the contacts to break off the circuit and ejects the plug 30 to its "off' position. In this off position, the plug 30 contacts are "dead" and separated from live parts, all of which are isolated and made inaccessible to users. Lastly, rotation of the plug 30 and closing of a safety shutter 24 during plug removal ensures that all arc paths are blocked before the plug 30 and the housing 40 can be physically removed, and safely so.

[0013] The housing, generally identified 40, has two sides - a supply side and an equipment side. The connection device is attached or attachable to the supply side of the housing 40 and an electrical cable or other connector 50^'to the wind tower elevator is attached on the equipment side of the housing 40. The housing 40 of the present invention further comprises a cover 42. A portion 44 of the cover 42 is transparent or clear so as to allow the user to visualize indicator lights 46 for the fuses (not shown) that are contained within the housing 40. That is, the fuse housing 40 has indicator lights 46 for showing that the fuses are either active or blown. A fuse is a sacrificial electrical device that interrupts excessive current ("blows") so that further damage by overheating or fire is prevented. The sight window 44 on front the housing 40 allows the user to visualize fuse status ("blown" or "not blown") without the need for opening the housing 40. When a fuse is blown, an indicator light 46 for that fuse is lit indicating to the user that the corresponding fuse has, in fact, blown.

[0014] In the assembly of the present invention, a fused disconnect switch or a circuit breaker is used as a service disconnect, i.e. a main switch used to disconnect utility power from the wind turbine elevator. Facility personnel generally don't have access to the utility assembly to turn the power off upstream of the service disconnect. Upstream disconnecting means and overcurrent protection devices are often utility- owned fuse cutouts on the primary side of a utility-owned transformer. The fuses often have slow characteristics resulting in high arc-flash hazard at the service disconnect switch. The hazard may be too high to safely open the enclosure of the service disconnect, even with protective equipment in place. If the service disconnect has fuses which need replacing, or the equipment otherwise needs inspecting, adjusting, or testing, the only safe solution is to call the utility and wait for a utility line crew to disconnect power on the primary side on the utility transformer, which is not acceptable for production purposes. The assembly of the present invention includes that portion of the power cabling to the facility and to the disconnect apparatus 10. It also includes the electrical connection device 20, the plug 30, the housing 40, with fuses, and the power cabling, via the cable outlet 50, to the wind tower elevator.

[0015] In application, disconnection of the connection device 20 from the plug 30 removes power from the fuse housing 40, which means that fuses can be changed without any requirement for personal protective equipment by the worker. Further, the connection device 20 and plug 30 can be easily "locked out" by use of a padlock (not shown) to prevent reconnection during servicing of the housing 40, its internal fuses or the elevator and its drive motors.

Claims

The details of the invention having been disclosed in accordance with the foregoing, I claim:

1. A wind turbine elevator disconnect apparatus for increasing the safety of a worker when power to a wind tower elevator requires making or breaking the electrical connection of the elevator to its electrical supply, the apparatus comprising:

a fuse housing comprising a supply side and an equipment side;

the supply side of the fuse housing comprising a plug;

the equipment side of the fuse housing comprising a cable outlet;

an electrical connection device attached to the plug; and

a fuse housing cover, the fuse housing cover comprising a transparent portion which is a sight window;

a plurality of fuses disposed within the fuse housing; and

a plurality of indicator lights disposed within the fuse housing, the indicator lights being visible through the sight window portion of the fuse housing cover and each indicator light being associated with a fuse; wherein the apparatus eliminates the risk of arc flash and allows workers to disconnect a wind tower elevator from its electrical supply without the use of special personal protective equipment.

2. The wind turbine elevator disconnect apparatus of claim 1 wherein the electrical connection device comprises a socket having at least one axial pressure contact arranged in insulation and at least one annular groove, and wherein the plug comprises at least one tubular contact that is coaxial with the direction of coupling of the plug with the socket.

3. The wind turbine elevator disconnect apparatus of claim 2 wherein the at least one tubular contact comprises a leading end surface having an end face and is structured to cooperate with the at least one axial pressure contact of the socket; wherein the at least one annular groove opens out axially and is structured to receive the at least one tubular contact, and wherein at least a portion of the end face of the leading end of the at least one tubular contact presses against the at least one axial pressure contact when the at least one tubular contact is positioned in the at least one annular groove and when the plug is coupled with the socket; and wherein the electrical connection device is configured to isolate the making and breaking of contacts within an enclosed arc chamber.

4. The wind turbine elevator disconnect apparatus of claim 3 wherein the connection device comprises an off button which, when the off button is pushed, opens a spring-loaded operating mechanism which opens the contacts to break off the circuit and ejects the plug to an "off" position,

5. The wind turbine elevator disconnect apparatus of claim 4 wherein the connection device comprises a safety shutter which closes during plug removal to ensure that all arc paths are blocked before the plug can be removed from the connection device.

6. A wind turbine elevator disconnect assembly that comprises the wind turbine elevator disconnect apparatus of claim 1 and further comprises:

a service disconnect to disconnect utility power from the wind turbine elevator;

power cabling from the service disconnect to the electrical connection device; and

power cabling from the cable outlet to the wind tower elevator and its drive motors.

7. The wind turbine elevator disconnect assembly of claim 6 wherein the service disconnect is a fused disconnect switch or a circuit breaker.

8. A method for using the wind turbine elevator disconnect apparatus of claim 1 comprising the steps of:

disconnecting the connection device from the fuse housing, thereby removing electrical power to the fuse housing;

servicing of the wind turbine tower elevator and its drive motors; and reconnecting the connection device to the fuse housing, thereby restoring electrical power to the fuse housing and to the wind turbine tower elevator and its drive motors.

9. A method for using the wind turbine elevator disconnect apparatus of claim 1 comprising the steps of:

observing an indicator light through the sight glass of the fuse housing showing that a fuse within the fuse housing has blown;

disconnecting the connection device from the fuse housing, thereby removing electrical power to the fuse housing;

opening the fuse housing to access the fuses;

changing out the fuses that have blown;

closing the fuse housing; and

reconnecting the connection device to the fuse housing, thereby restoring electrical power to the fuse housing and to the wind turbine tower elevator and its drive motors.