Petition - Docket No. 1998-104-C

In the matter of            Petition for Modification

U.S. Steel Mining, LLC

Gary No. 50 Mine

I.D. No. 46-01816            Docket No. M-98-104-C

PROPOSED DECISION AND ORDER

On November 5, 1998, a petition was filed seeking a modification of the application of 30 CFR 75.1002 to Petitioner's Gary No. 50 Mine located in Wyoming County, West Virginia. 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 recommendation, this Proposed Decision and Order is issued.

Finding of Fact and Conclusion of Law

The alternative method proposed by the Petitioner (as amended by the recommendations of MSHA) will at all times guarantee no less than the same measure of protection afforded the miners under 30 CFR 75.1002.

On the basis of the petition and the findings of MSHA's investigation, U.S. Steel Mining, LLC, is granted a modification of the application of 30 CFR 75.1002 to its Gary No. 50 Mine.

ORDER

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 U.S. Steel Mining, LLC's Petition for Modification of the application of 30 CFR 75.1002 in the Gary No. 50 Mine is hereby:

GRANTED, conditioned upon compliance with the following terms and conditions:

1. The nominal voltage of the longwall face conveyor circuit(s) shall not exceed 4,160 volts.
2. The nominal voltage of the longwall control circuit shall not exceed 120 volts. The control transformer supplying control voltage shall have a Faraday shield connected to ground with a No. 12 A.W.G. grounding conductor.
3. Ground-fault current for the 4160-volt circuits shall be limited by a neutral grounding resistor to not more than 0.50 ampere or the setting specified in the longwall approval documentation, if less.
4. Each high-voltage motor circuit shall be provided with instantaneous ground-fault protection set at not more than 40 percent of the ground-fault current limited by the neutral grounding resistor or not more than 0.125 ampere, whichever is less.
5. The high-voltage circuit(s) from the longwall power center to 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 or not more than 0.125 ampere, whichever is less. Where two high-voltage cables are used to supply power to a common buss in the high-voltage longwall controller, and each cable has a ground-fault relay, each individual relay shall be set at appropriate values based on the number of relays. A time delay may be permitted for coordination with the downstream ground-fault protection 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 second.
6. Each ground-fault current device specified in item Nos. 4 and 5 above shall be provided with a test circuit to test the device at 50 percent or less of the current rating of the grounding resistor which shall cause the corresponding circuit breaker to trip open. The test circuit shall not subject the equipment to an actual phase-to-ground fault. Current transformers used to provide ground-fault protection shall be a single window type, which shall encircle the load power conductors.
7. The longwall power center shall be provided with backup ground-fault protection that shall deenergize the incoming high-voltage 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 grounding resistor if a ground-fault occurs. A time delay for coordination with downstream ground-fault protection 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.
8. The high-voltage neutral grounding resistor shall be provided with a thermal protection that will deenergize the longwall power center if the grounding resistor is subjected to a sustained ground-fault. 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 that will deenergize the incoming high-voltage circuit supplying the power center.
9. 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. A time delay of not more than .050 seconds may be permitted for motors with high inrush currents. All components that provide short-circuit protection shall have sufficient interrupting rating to safely interrupt the maximum calculated available fault current.
10. The 4,160-volt circuit(s) from the longwall power center to the longwall controller shall be provided with short-circuit protection by means of a high-voltage circuit breaker in the longwall power center. This circuit breaker shall be set at not more than 75 percent of the minimum available phase-to-phase short-circuit current at the longwall controller or the setting specified in the longwall approval documentation, whichever is less. A time delay may be permitted for coordination with downstream short-circuit protection devices. The time delay shall not exceed the setting specified in the approval documentation, or 0.25 seconds, whichever is less.
11. Where two high-voltage cables are used to supply a common buss in the longwall controller and each cable has an overcurrent relay, each overcurrent relay shall be set at an appropriate value determined by the number of relays used. A time delay may be permitted for coordination with downstream short-circuit protection devices. The time delay shall not exceed the setting specified in the approval documentation, or 0.25 seconds, whichever is less.
12. The grounding circuit from the longwall power center to the longwall controller shall be monitored by an MSHA-accepted ground monitor system. When two high-voltage cables are used to supply power to a common bus in the longwall controller, each cable shall be provided with an MSHA accepted ground-wire monitoring system. The ground-wire monitoring circuits shall deenergize both cables when either the grounding circuit or ground-wire monitoring circuit of either cable becomes severed or open. One circuit breaker, or two circuit breakers that are electrically and mechanically interlocked shall be used in the power center to protect all cables. The cables shall be interlocked such that the circuit breaker(s) will open when either cable is disconnected. Each ground wire monitoring system shall be provided with a test circuit to functionally test each ground-wire monitoring system and cause the circuit breaker(s) to trip open.
13. The longwall power center shall be equipped with a primary visible disconnecting device installed to deenergize and ground the primary of the high-voltage transformer(s) when the device is open. A visible disconnecting device shall also be provided for control and communications circuits.
14. 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;

b.                  when the primary disconnecting device is in the "closed" position, the control circuit can be powered only through an auxiliary switch in the "normal" position; and

c.                   the disconnecting device can be locked in the "open" position.

1. The longwall power center shall be equipped with a secondary disconnecting device or cable couplers installed to deenergize and ground all high-voltage cables extending to the longwall controller when the device is open.
2. The longwall controller shall be provided with a main visible disconnecting device installed to deenergize all high-voltage power conductors extending from the enclosure.
3. The control circuit for the longwall controller shall be interlocked with the main visible disconnecting device in the power center so that:
   
   

a.  when the main disconnecting device is in the "open" position, the control circuit can only be powered through an auxiliary switch in the "test" position; 

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; and

c.  the disconnecting device can be locked in the "open" position.

1. The longwall controller shall be provided with disconnecting devices and/or cable couplers installed to disconnect each high-voltage cable extending from the controller.

19.     Each disconnecting device shall be installed so that:
a.  It can be determined by visual observation that the disconnecting device contacts are open without removing any cover(s);

b.  All high-voltage power conductors can be grounded when the disconnecting device is in the "open" position; 

c.  The disconnecting device can be locked in the "open" position; and

d.  If a cable coupler is used as the disconnecting device, the phase conductors in the high-voltage cable shall be connected to a frame ground common to the enclosure by means of a grounding receptacle provided and a dust cover shall be placed on the enclosure receptacle from which the cable was disconnected. 

For the purpose of testing, troubleshooting or fault finding, the deenergized high-voltage cable shall be allowed to be disconnected from the provided grounding receptacle only for that period of time necessary to locate and determine the defective condition. The high-voltage cable must be reconnected to the grounding receptacle prior to work being performed to correct the defective condition.

A sign shall be located near the disconnecting device identifying the circuit(s) the device disconnects.

1. Each 4,160-volt cable installed as part of the longwall mining system shall be type SHD-GC or other 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. This condition is not applicable if a separate 101 (c) petition for modification for the use of other cable designs has been granted by MSHA. The cables shall be designed and constructed to withstand the conditions in an underground environment and shall enter and exit the permissible mining equipment through approved stuffing box lead entrances or approved cable couplers. 
2. 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 a kit that has been accepted by MSHA as flame-resistant. Each splice or major repair shall be made so that all cable components are replaced with similar components. Repairs are considered major if there is any damage to the shielding,, grounding conductors, ground-check circuit conductors, inner conductor insulation or load power conductors. Minor repairs to the cable jacket may be made by using tape accepted by MSHA as flame-resistant.
   
   Splices and repairs in high-voltage power cables shall be made only by a qualified person (as provided in 30 CFR 75.153) who has received "hands on" training in the proper methods of splicing and repairing high-voltage cables. 
3. 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 shall be used to minimize the possibility of miners contacting the cables. 
4. Adequate means to secure the connection boxes or in-line connectors at the middle of the face shall be installed to provide secure connection of the high-voltage cables.
5. High-voltage cables routed along the stageloader shall be protected by grounded metal barriers or reinforced non-conductive materials.
6. Miners shall not be permitted to handle high-voltage cables unless the cables have been deenergized.
7. Barriers shall be provided and covers shall be arranged so that miners can work in the 4,160-volt section of the power center or the starter enclosure without being exposed to energized conductors or parts, including capacitors, when the primary disconnecting device is in the "open" and "grounded" position.
8. Barriers shall be provided and covers shall be arranged so that miners can work in the control compartment(s) of the power center and starter enclosure without being exposed to energized conductors or parts that exceed nominal 150 volts (except for the capacitance tripping circuit) regardless of the position of the primary disconnecting device.
9. Barriers shall be provided and covers shall be arranged so that miners can work in the motor contactor compartments of the shearer without being exposed to energized high-voltage conductors or parts that exceed nominal 150 volts when the secondary disconnecting device is in the "open" and "grounded" position.
10. Barriers shall be provided and covers arranged so that miners can work in the communication and control compartments of the longwall controller without being exposed to energized conductors or parts that exceed a nominal 150 volts regardless of the position of the secondary disconnecting device.
11. Cover interlock switches shall be provided to automatically deenergize the incoming high-voltage circuit to the power center when any cover, that provides access to energized high-voltage conductors or parts, including capacitors, is removed.
12. Cover interlock switches shall be provided and wired to automatically deenergize the circuit supplying power to the longwall controller when any cover, that provides access to energized 4,160-volt conductors or parts, is removed. This condition does not apply to covers installed on motor junction boxes.

32.     Before any electrical work (including testing, troubleshooting and faultfinding) is performed on any high-voltage equipment or cable, a qualified person (as provided in 30 CFR 75.153) shall:
a.  Determine that the contacts of the appropriate disconnecting device are "open" and "grounded";

b.  Lockout and tag the disconnecting device;

c.  Assure that capacitors have been discharged and "grounded"; and

d.  If a cable coupler is used as the disconnecting device, the load power conductors shall be connected to the frame ground of the enclosure by using a "grounding" receptacle.

1. The Petitioner's alternative method shall not be implemented until all personnel who perform maintenance on the longwall have received training in high-voltage safety and maintenance procedures. Also, all personnel who work in proximity of the 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 MSHA representatives and to other interested parties.
2. The high-voltage longwall mining equipment shall be MSHA approved.
3. 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. The Petitioner shall notify MSHA before mining equipment is put into service in any subsequent longwall panel. The notice shall advise MSHA of any modifications to the equipment and provide a reasonable time for MSHA to schedule an inspection of the equipment if necessary.
4. Methane monitors shall be installed and maintained on the longwall face in accordance with 30 CFR 75.342.
5. Self-contained self rescuers (SCSR's) shall be worn or stored in accordance with the approved plan to meet the requirements of 30 CFR 75.1714.
6. A travelway shall be maintained on the tailgate of the longwall panel. If for any reason the tailgate travelway becomes impassable, management shall notify the representative of the miners and the tailgate blockage plan approved by MSHA under 30 CFR 75.222(g) shall be put into effect. All tailgate travelways shall be maintained to ensure passage at all times of any person, including disabled persons, subject to the tailgate blockage plan referenced above.
7. At least two intake escapeways, one of which shall be a primary escapeway meeting the requirements of 30 CFR 75.380, shall be provided on the headgate of all longwall sections.
8. Sufficient rock dust shall be applied throughout the panel to be in compliance with 30 CFR 75.403, and to adequately control float dust. A rock duster shall be installed to regularly dust the immediate area where air accesses into the gob while the longwall is in operation. Should the rock duster become inoperative, necessary repairs shall commence immediately. Other alternative methods may be used until repairs are complete.
9. 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 task 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, as amended, (Federal Register 53430, December 28, 1990) within 30 days. The request for hearing must be filed with the 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 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