In the matter of Petition for Modification
Genwal Resources, Inc.
Crandall Canyon Mine
I.D. No. 42-01715 Docket No. M-97-014-C
Date Issued: 08/17/1997
PROPOSED DECISION AND ORDER
On January 28, 1997, a petition was filed seeking a modification of the application of 30 CFR 75.1002 to Petitioner's Crandall Canyon Mine, located in Emery 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 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, Genwal Resources, Incorporated, is granted a modification of the application of 30 CFR 75.1002 to its Crandall Canyon 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 Genwal Resources, Incorporated's Petition for Modification of the application of 30 CFR 75.1002 in the Crandall Canyon Mine is hereby:
GRANTED, conditioned upon compliance with the following terms and conditions:
1. The nominal voltage of the longwall power circuits shall not exceed 2,400 volts.
2. The nominal voltage of the longwall control circuits shall not exceed 120 volts.
3. Ground-fault current for the 2,400-volt circuits shall be limited by a neutral grounding resistor to not more than 0.50 ampere.
4. Each 2,400-volt motor circuit and shearer circuit shall be provided with instantaneous ground-fault protection set not to exceed 0.125 ampere.
5. The longwall power center shall be provided with ground-fault protection set to deenergize the 12,470-volt circuit breaker in the longwall power center when a ground-fault of not more than 0.125 ampere occurs. Where two or more high-voltage cables are used to supply power to a common bus in the high-voltage longwall controller enclosure and each cable has a ground-fault relay, each ground-fault relay shall be set at an appropriate value determined by the number of relays used. 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.
6. The longwall power center shall be provided with backup ground-fault protection that shall deenergize the 12,470-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 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 second.
7. The high-voltage neutral grounding resistor shall be provided with over temperature protection that will deenergize the incoming power to the longwall power center if the grounding resistor is subjected to a sustained ground-fault. The over temperature protection shall not be dependent upon control power and shall operate at either 50 percent of the maximum temperature rise of the grounding resistor, or 150o (302o F) centigrade, whichever is less.
8. Each high-voltage motor circuit shall be provided with instantaneous short-circuit protection by means of a vacuum breaker 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 respective motor terminals, whichever is less.
9. The 2,400-volt circuits from the longwall power center to the longwall controller shall be provided with short-circuit protection by means of a vacuum 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 current at the longwall controller terminals 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.
10. 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 monitor(s) shall deenergize both cables when the ground or ground-wire monitoring conductor(s) of either cable is severed or open. The cables shall be interlocked such that the vacuum circuit breaker will open when either cable is disconnected.
11. The longwall power center shall be provided with a primary (12,470-volt) visible disconnecting device installed to deenergize and ground the primary of the high-voltage transformer when the device is open.
12. The longwall power center shall be provided with a secondary (2,400-volt) disconnecting device installed to deenergize and ground all high-voltage cables extending to the longwall controller when the device is in the open position and/or cable couplers installed to deenergize each high voltage power conductor extending from the power center.
13. The longwall controller shall be equipped with a main visible disconnecting device installed to deenergize all high-voltage power conductors extending from the controller when the disconnecting device is in the open position and/or cable couplers installed to deenergize each high voltage power conductor extending from the power center.
14. Each disconnecting device shall be installed so that:
a. It can be determined by visual observation that the contacts are opened when the device is in the “open” position without removing any cover(s);
b. All load side power conductors shall be grounded when the device is in the “open” position; and
c. The device can be locked in the “open” position when the device is used to disconnect circuit(s).
A sign shall be located near the switch identifying the circuit(s) the device disconnects.
15. Each high-voltage 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 of 30 CFR 75.804 has been granted by MSHA at this mine.
16. 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. 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, semi-conducting tape, inner conductor insulation, power conductors or grounding conductors. Kits having tape as the outer jacket are not acceptable.
17. The 2,400-volt cables shall be guarded at appropriate locations with MSHA approved reinforced flame-resistant nonconductive hose conduit. If the conduit contains metal, it must be grounded to the system grounding medium. The guarding shall be installed at the following locations:
a. Where miners regularly work or travel over or under cables.
b. Any place where the cable(s) leaves the cable handling and support system to extend to electric components, or at mid-face where slack cable may be exposed; and
c. Where high-voltage cables are installed in the same raceway as low-voltage cables.
The guarding shall protect the cables from damage and shall minimize miners’ contact with the cables. Additionally, guarding shall be provided on high-voltage cables in belt conveyor entries during cleanup and belt structure removal if the cables are within 12 inches of mobile equipment, unless the cable is deenergized.
18. 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.
19. Cable handling and support systems (for example, Bretby and monorail systems) that are designed, installed, and maintained to protect the 2,400-volt cables from damage and to minimize the possibility of miners contacting the cable shall be used.
20. Energized high-voltage cables shall not be handled except when shearer cables need to be trained (i.e. shearer cable inadvertently coming out of the cable trough). When cables need to be trained, high-voltage insulating gloves or high-voltage insulating sticks shall be used for protection against shock hazard.
21. 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. A sufficient storage facility shall be provided for the cable handling equipment. Insulated personal protective equipment shall be rated for a minimum of 7,500-volts and 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.
22. Barriers shall be provided and covers shall be arranged so that miners can work in the 2,400-volt section of the power center without being exposed to energized 2,400-volt conductors or parts, including capacitors, when the input disconnect switch is in the “open” and “grounded” position.
23. Barriers shall be provided and covers shall be arranged so that miners can work in the control and communication compartments of the longwall controller without being exposed to energized high-voltage conductors or parts, including capacitors, regardless of the position of the primary disconnect switch.
24. 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 nominal 120-volts when the main disconnect switch is in the “open” and “grounded” position.
25. 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 nominal 120-volts when the main disconnect switch is in the “open” and “grounded” position.
26. 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.
27. Cover interlock switches shall be provided to automatically deenergize the 2,400-volt circuit(s) supplying the longwall controller when any cover of the controller that provides access to energized 2,400-volt conductors or parts is removed.
28. 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 (in the test position, no voltage greater than 120-volts nominal shall exit the controller; and
b. When the main disconnecting device is in the “closed” position, the control circuit can be powered only through the auxiliary switch in the “normal” position.
29. The control circuits for 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 nominal 120-volts shall exit the controller); 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.
30. 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 2,400-volt conductors and parts to warn miners against entering these compartments before all 2,400-volt conductors and parts, including capacitors, have been discharged and grounded.
31. 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.
32. Before any electrical work (including testing, troubleshooting, and fault-finding) is performed inside any compartment of the power center, a qualified person (as provided in 30 CFR 75.153) shall:
a. Determine that the contacts of the primary disconnecting device in the power center are “open” and “grounded”;
b. Lockout and tag the disconnecting device; and
c. Ensure that all 2,400-volt capacitors have been discharged and grounded.
31. Before any electrical work (including testing, troubleshooting, and fault-finding) is performed inside the input high-voltage compartment 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 disconnecting device in the power center are “open” and “grounded”; and
b. Lockout and tag the secondary disconnecting device at the power center.
32. Before any electrical work (including testing, troubleshooting, and fault-finding) is performed inside the contactor compartment for the controller, a qualified person (as provided in 30 CFR 75.153) shall:
a. Determine that the contacts of the primary disconnect device in the controller are “open” and “grounded”; and
b. lockout and tag the primary disconnect at the controller.
33. Before any electrical work (including testing, troubleshooting, and fault-finding) is performed on any high-voltage equipment or cable supplied from the longwall controller, a qualified person (as provided in 30 CFR 75.153) shall:
a If a visible disconnect device is not located at the controller output for the associated circuit, then:
(1) Determine that the high-voltage circuit has been deenergized before disconnecting the cable from the controller;
(2) Connect the phase conductors in the high-voltage cable to the frame ground of the controller by means of the grounding receptacle provided;
(3) Lockout and tag the disconnecting device in this position; and
(4) Place a dust cover on the controller receptacle from which the cable was disconnected.
b. If a visible disconnect is located at the controller output for the associated circuit, then:
(1) Determine that the contacts of the disconnecting device for the circuit are “open” and “grounded”; and
(2) Lockout and tag the disconnecting device.
34. The Petitioner’s alternative method shall not be implemented until all personnel who perform maintenance on the longwall 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.
35. The high-voltage longwall mining equipment shall be MSHA approved.
36. 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.
37. A methane monitor shall be installed and maintained on the longwall face in accordance with 30 CFR 75.342 requirements.
38. Self-contained self-rescuers (SCSR’s) shall be stored in the vicinity of the headgate and shall be stored along the face or at the tailgate of the longwall section to meet the requirements of 30 CFR 75.1714.
39. 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 special terms and conditions stated in the Proposed Decision and Order. In addition, the following training shall be adopted:
a. Safety precautions for the handling and use of high-voltage cables and equipment, for all miners assigned to work in the area of the high-voltage longwall.
b. Specialized training for qualified electricians that will be required to repair, maintain and/or trouble-short the deenergized high-voltage cables or equipment.
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