On October 31, 1995, a petition was filed seeking a modification of the application of 30 CFR 75.1002 to Petitioner's Willow Creek Mine, located in Carbon County, Utah. The Petitioner alleges that the alternative method outlined in the petition will at all times guarantee no less than the same measure of protection afforded by the standard.
MSHA personnel conducted an investigation of the petition and filed a report of their findings and recommendations with the Administrator for Coal Mine Safety and Health. After a careful review of the entire record, including the petition and MSHA's investigative report and recommendations, and supplemental information on the type of high voltage longwall equipment to be used received on July 16, 1997, this Proposed Decision and Order is issued.
Wherefore, pursuant to the authority delegated by the Secretary of Labor to the Administrator for Coal Mine Safety and Health, and pursuant to Section 101(c) of the Federal Mine Safety and Health Act of 1977, 30 U.S.C., sec. 811(c), it is ordered that Cyprus Plateau Mining Corporation's Petition for Modification of the application of 30 CFR 75.1002 in the Willow Creek Mine is hereby:
GRANTED, conditioned upon compliance with the following terms and conditions:
1. The nominal voltage of the high-voltage power circuits shall not exceed 4,160 volts. The nominal voltage of the power circuits supplying the hydraulic pump motors shall not exceed 995-volts.
2. The nominal voltage of the longwall control circuits shall not exceed 120 volts.
3. Ground-fault current for the 4,160 volt circuits shall be limited by a neutral grounding resistor to not more than 0.5 amperes. Current transformers used for the ground-fault protection shall be the single-window type and shall be installed to encircle all three-phase conductors.
4. Each 4,160 volt motor circuit and shearer circuit shall be provided with instantaneous ground-fault protection set at not more than 40 percent of the maximum current limited by the neutral grounding resistor or 0.125 ampere, whichever is less.
5. The high-voltage circuit from the longwall power center to the longwall controller shall be provided with ground-fault protection set at not more than 40 percent of the ground-fault current limited by the neutral grounding resistor. A time delay may be permitted for coordination with downstream ground-fault protective devices. The time delay shall be set at the lowest practical value that permits reliable coordination; however, in no case shall the time delay exceed 0.25 seconds.
6. The longwall power center shall be provided with backup ground-fault protection that shall deenergize the 4,160 volt circuit breaker in the longwall power center if a ground-fault occurs with the neutral grounding resistor open. This protection shall be set at 40 percent of the maximum voltage that could appear across the neutral ground resistor if a ground-fault occurs with the grounding resistor open. A time delay for coordination with downstream ground-fault protective devices shall be set at the lowest practical value that permits reliable coordination; however, in no case shall the time delay exceed 0.25 seconds.
7. The high-voltage neutral grounding resistor shall be provided with thermal protection that will deenergize the incoming power to the longwall power center if the grounding resistor is subjected to a sustained ground-fault. The thermal protection shall operate at either 50 percent of the maximum temperature rise of the grounding resistor, or 1500 C (3020 F), whichever is less. The thermal protection shall not be dependent upon control power and may consist of a current transformer and overcurrent relay in the grounding resistor circuit.
8. Each high-voltage motor circuit shall be provided with instantaneous short-circuit protection set at not more than the setting specified in the longwall approval documentation or 75 percent of the minimum phase-to-phase short-circuit current available at the motor terminals, whichever is less.
9. All components that provide short-circuit protection shall have an interruption rating in accordance with the maximum short circuit currents available inby that circuit interrupting device(s), and shall be rated for the maximum phase-to-phase voltage of the circuit. Circuit interrupting device(s) shall not recluse automatically.
10. The 4,160 volt circuit(s) from the longwall power center to the longwall contactor box shall be provided with short-circuit protection set at not more than 2,500 amperes or 75 percent of the minimum available fault current, whichever is less. A time delay shall be permitted for coordination with downstream short-circuit protective devices. The time delay shall be set at the lowest practical value that permits reliable coordination; however, in no case shall the time delay exceed 0.25 seconds or the setting specified in the longwall approval documentation, if less, shall apply.
11. Where two high-voltage cables are used to supply power to the longwall controller, both high-voltage cables shall be provided with ground-wire monitoring circuits. The ground-wire monitoring circuits shall deenergize both cables when the grounding conductor(s) of either cable become severed or open. The cables shall be interlocked such that the breaker will open when either cable is disconnected.
12. The longwall power center shall be equipped with a primary visible disconnecting device installed to deenergize the primary of the high-voltage transformer when the device is open.
13. The longwall power center shall be equipped with a secondary disconnecting device installed to deenergize all high-voltage cables extending to the longwall controller when the device is open.
14. The longwall controller shall be provided with a main visible disconnecting device installed to deenergize all high-voltage power conductors extending from the controller.
15. The longwall controller shall be provided with an auxiliary visible disconnecting device installed to deenergize all high-voltage power conductors extending from the controller, with the exception of the shearer circuit.
16. The longwall controller shall be provided with a shearer visible disconnecting device installed to deenergize the high-voltage power conductors extending to the shearer from the controller.
17. Each disconnecting device shall be installed so that:
(a) It can be determined by visual observation that the contacts are opened without removing any cover(s);
(b) All load power conductors can be grounded when the device is in the “open” position; and
(c) The device can be locked in the “open” position.
A sign shall be located near the switch identifying the circuit(s) the device disconnects.
18. Each high-voltage cable shall be type SHD-GC or similar cable that meets the requirements of 30 CFR 75.804, with a minimum rating of 5,000 volts and shall have an outer jacket that has been accepted by MSHA as flame resistant.
19. Each splice or repair in a high-voltage cable shall be made in a workmanlike manner and in accordance with the instructions of the manufacturer of the splice or repair materials. The outer jacket of each splice or repair shall be vulcanized with flame-resistant material or made with kit that has been accepted by MSHA as flame-resistant. Kits having tape as the outer jacket are not acceptable.
20. The high-voltage cables shall be attached to the stage loader and protected by grounded metal barriers or reinforced nonconductive, flame-resistant material across the stage loader.
21. High-voltage cables shall be guarded at the following locations:
(a) Where miners regularly work or travel over the cables unless the cables are 6 ½ feet or more above the floor or rails; and
(b) Where the cables leave the cable handling and support systems to extend to electric components.
The guarding shall protect the cables from damage and shall minimize the possibility of miners contacting the cable(s). The guarding shall be of grounded metal or reinforced nonconductive, flame-resistant material. Additionally, guarding shall be provided on high-voltage cables in belt conveyor entries during clean-up and belt structure removal if the cables are within 12 inches of mobile equipment, unless deenergized.
22. Adequate means to secure the connection box or in-line connector at the middle of the face shall be installed to provide secure connections of the high-voltage cables.
23. Cable handling and support systems (for example, Bretby and monorail systems) that are designed, installed, and maintained to protect the high-voltage cables from damage and to minimize the possibility of miners contacting the cables shall be used. The cable handling system shall assure that the minimum bending radius of the cable is not less than six times the diameter of the cable.
24. Energized high-voltage cables shall not be handled except when motor or shearer cables need to be trained (shearer cable inadvertently coming out of the cable trough). During normal operations of making power moves or when it becomes necessary to add or move additional high-voltage cable, the high-voltage cable shall be deenergized, locked-out and tagged by a qualified person (as provided in 30 CFR 75.153), prior to the high-voltage cable being handled. The input high-voltage power cable shall be deenergized, locked-out and tagged by a qualified person (as provided in 30 CFR 75.153) prior to a power center move being made.
25. High-voltage personal protective equipment, including rubber gloves, shall be visually inspected before each use. High-voltage rubber gloves shall be air tested before each use to ensure their effectiveness. Damaged or defective protective equipment shall be removed from the mine or destroyed. Insulated personal protective equipment shall be rated for a minimum of 7,500 volts and shall be electrically tested and stored in accordance with the schedule listed in 30 CFR 75.705-8. These tests are to be conducted as described in a nationally recognized standard, such as ASTM 496-91.
26. Barriers shall be provided and covers shall be arranged so that miners can work in the 4,160-volt section of the power center without being exposed to energized 4,160-volt conductors or parts, including capacitors, when the primary disconnect switch is in the “open” and “grounded” position.
27. Barriers shall be provided and covers shall be arranged so that miners can work in the control compartment of the power center without being exposed to energized high-voltage conductors or parts regardless of the position of the primary disconnect switch.
28. Barriers shall be provided and covers shall be arranged so that miners can work in the motor contactor compartments of the longwall controller without being exposed to energized conductors or parts that exceed 120-volts phase-to-ground when the main disconnect switch is in the “open” and “grounded” position.
29. Barriers shall be provided and covers shall be arranged so that miners can work in the longwall communication and control compartments of the longwall controller without being exposed to energized conductors or parts that exceed 120-volts phase-to-ground regardless of the position of the main disconnect switch.
30. Cover interlock switches shall be provided to automatically deenergize the high-voltage circuit supplying the longwall power center when any cover of the power center that provides access to energized high-voltage conductors or parts is removed.
31. Cover interlock switches shall be provided to automatically deenergize the 4,160-volt circuit supplying the longwall controller when any cover that provides access to energized 4,160-volt conductors or parts is removed.
32. The control circuit for the power center shall be interlocked with the primary disconnecting device in the power center so that:
(a) When the primary disconnecting device is in the “open” position, the control circuit can only be powered through an auxiliary switch in the “test” position; and
(b) When the main disconnecting device is in the “closed” position, the control circuit can be powered only through an auxiliary switch in the “normal” position.
33. The control circuits for the high-voltage and other circuits in the longwall controller shall be interlocked with the main disconnecting device so that:
(a) When the main disconnecting device is in the “open” position, the control circuit can only be powered through an auxiliary control switch in the “test” position (in the test position, no voltage greater than 120 volts nominal shall exit the controller);
(b) When the main disconnecting device is in the “closed” position, the control circuit can be powered only through an auxiliary control switch in the “normal” position; and
(c) Neither the main circuit breaker nor the main disconnecting device can be closed unless the auxiliary switch is in the ”normal” position without dropping out the incoming high voltage power feed.
34. Caution labels shall be installed and maintained on the covers of the compartments of the longwall power center containing the primary disconnecting device to warn miners against entering these compartments before deenergizing the incoming power to the power center. Also, caution labels shall be installed and maintained on all covers that provide access to 4,160-volt conductors and parts to warn miners against entering these compartments before all 4,160-volt capacitors have been discharged and grounded.
35. Caution labels shall be installed and maintained on the covers of the compartments of the longwall controller containing the controller main disconnecting device to warn miners against entering these compartments before deenergizing the incoming power to the power center or controller.
36. Before any work (including testing, troubleshooting, and fault finding) is performed inside any compartment of the power center containing 4,160-volts,a qualified person as provided in 30 CFR 75.153 shall:
(a) Determine that the contacts of the main disconnecting device in the longwall power center are open and the 4,160-volt circuit is grounded;
(b) Lock out and tag the disconnecting device in the longwall power center; and
(c) Assure that all capacitors have been discharged and grounded.
37. Before any electrical work (including testing, troubleshooting, and fault finding) is performed inside the input high-voltage compartments of the controller or on the high-voltage cable(s) supplying the controller, a qualified person (as provided in 30 CFR 75.153) shall:
(a) Determine, at the power center, that the contacts of the secondary disconnect are “open” and “grounded”; and
(b) Lockout and tag the longwall feed disconnect at the power center.
38. Before any electrical work (including testing, troubleshooting and fault-finding) is performed inside the contactor compartments of the controller, a qualified person (as provided in 30 CFR 75.153) shall;
(a) Determine that the contacts of the main disconnect switch in the controller are “open” and “grounded”; and
(b) Lockout and tag the main disconnect switch at the controller.
39. Except for the shearer circuit, before any electrical work (including testing, troubleshooting, or fault-finding) is performed on any high-voltage equipment or cable(s) supplied from the longwall controller, a qualified person (as provided in 30 CFR 75.153) shall:
(a) Determine that the high-voltage cable is disconnected from the controller;
(b) Connect the phase conductors in the high-voltage cable to the frame ground of the controller by means of the grounding receptacle provided;
(c) Lockout and tag the disconnecting device in this position; and
(d) Place a dust cover on the controller receptacle from which the cable was disconnected.
40. Before any electrical work (including testing, trobleshooting and fault-finding) is performed on the shearer equipment or cable, supplied from the longwall controller, a qualified person (as provided in 30 CFR 75.153) shall:
(a) Determine that the contacts of the shearer disconnecting switch in the controller are “open” and “grounded” to the system ground; and
(b) Lockout and tag the shearer disconnecting switch at the controller.
41. The petitioner’s alternative method shall not be implemented until all personnel who perform maintenance on the longwall or miners who work in proximity of the high-voltage equipment have received training in high-voltage safety and maintenance procedures. Also, all personnel who move high-voltage equipment or cables shall be trained in high-voltage safety procedures. A record of this training shall be maintained and made available to authorized representatives and to miners at the mine.
42. The high-voltage longwall mining equipment shall be MSHA approved.
43. A methane monitor shall be installed and maintained on the longwall face in accordance with 30 CFR 75.342.
44. A minimum of 12 self-contained self-rescuers (SCSR’s) shall be stored in the vicinity of the headgate and minimum of 12 SCSR’s shall be stored along the longwall face or at the tailgate of the longwall section to meet the requirements of 30 CFR 75.1714.
45. The high-voltage longwall mining equipment shall not be put into service until after MSHA has inspected the equipment and determined that it is in compliance with all the above terms and conditions.
46. Within 60 days after this Proposed Decision and Order becomes final, the Petitioner shall submit proposed revisions for its approved 30 CFR Part 48 training plan to the Coal Mine Safety and Health District Manager. These proposed revisions shall specify initial and refresher training regarding the terms and conditions stated in the Proposed Decision and Order.
Any party to this action desiring a hearing on this matter must file in accordance with 30 CFR 44.14, within 30 days, a request with the Deputy Administrator for Coal Mine Safety and Health, 4015 Wilson Boulevard, Arlington, Virginia 22203.
If a hearing is requested, the request shall contain a concise summary of position on the issues of fact or law desired to be raised by the party requesting the hearing, including specific objections to the proposed decision. A party other than the Petitioner who has requested a hearing shall also comment upon all issues of fact or law presented in the petition, and any party to this action requesting a hearing may indicate a desired hearing site. If no request for a hearing is filed within 30 days after service thereof, the Decision and Order will become final and must be posted by the operator on the mine bulletin board at the mine.
_________________________________
Robert A. Elam
Deputy Administrator
for Coal Mine Safety and Health
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