W. Va. Code R. § 56-23-29
Current through Register Vol. XLI, No. 50, December 13, 2024
Section 56-23-29 - Electrical Provisions for Diesel-Powered Electrical Generators29.1. Electrical provisions for diesel-powered electrical generators used as an alternative to power centers for moving equipment in, out, and around the mine and to perform work in areas where permissible equipment is not required, must comply with the following:29.1.1. A grounding resistor rated for the phase-to-phase voltage of the system must be provided to limit the ground-fault current to not more than 0.5 amperes. 29.1.1.a. The grounding resistor(s) must be located:29.1.1.a.1. Between the wye-connected generator neutral and the generator frame or29.1.1.a.2. Between the wye-connected generator neutral and the generator frame and between the wye-connected transformer secondary and the transformer frame when an isolation transformer(s) is used and the generator is supplying power to the other equipment or29.1.1.a.3. Between the wye-connected generator neutral and the generator frame when an auto-transformer is used.29.2. Each three-phase output circuit of the generator must be equipped with a sensitive ground fault relay. The protective relay must be set to cause the circuit interrupting device that supplies power to the primary windings of each transformer to trip and shut down the diesel engine when a phase-to-frame fault of not more than 90 milliamperes occurs.29.3. The neutral grounding resistor shall be provided with backup ground fault protection that will shut down the diesel engine if a ground fault occurs with the neutral grounding resistor open.29.4. Each three-phase output circuit that supplies power to equipment must be equipped with an instantaneous sensitive ground-fault relay that will cause its respective circuit interrupting device(s) to trip and cause shutdown of the diesel engine when a phase-to-frame fault occurs. The grounded-phase protection must be set at not more than 90 milliamps. Current transformers used for the ground-fault protection must be single window-type and must be installed to encircle all three phase conductors. Equipment safety grounding conductors must not pass through or be connected in series with ground-fault current transformers.29.5. Each three-phase circuit interrupting device must be provided with a means to provide short-circuit, overcurrent, grounded-phase, under-voltage, and ground wire monitoring protection. The instantaneous only trip unit for the circuit interrupting device(s) in use must be adjusted to trip at not more than seventy-five percent (75%) of the minimum available short circuit current at the point where the portable cable enters the equipment, specified in Table 56-23A found at the end of this rule.29.6. The equipment portable cable length(s) must not exceed the length(s) specified in Table 56-23B found at the end of this rule.29.7. Permanent label(s) listing the maximum circuit interrupting device setting(s) and maximum portable cable length(s) must be installed on each instantaneous trip unit or be maintained near each three-phase circuit interrupting device. The permanent label(s) must be maintained legibly.29.8. The circuit interrupting device that supplies three-phase power circuit(s) to the equipment being powered must be limited to the use of only one circuit interrupting device at a time when equipment is being moved in, out, and around the mine.29.9. The grounding system must include an MSHA-accepted ground wire monitor system to assure that grounding conductor is connected to the frames of all equipment and to the frame of the generator. Double grounding will not be accepted in lieu of ground monitoring.29.10. All trailing cables extending from the generator to equipment must comply with the design of trailing cables for medium-voltage circuits.29.11. Trailing cables for medium-voltage circuits shall include grounding conductors, a ground check conductor, and grounded metallic shields around each power conductor or a ground metallic shield over the assembly, except that on equipment employing cable reels, cables without shields may be used if the insulation is rated 2,000 volts or more.29.12. A strain relief device must be provided on each end of the trailing cables that extends between the generator and the piece of equipment being powered.29.13. Prior to moving each piece of equipment or performing work, a functional test of each ground fault and ground wire monitor system must be performed by a qualified electrician. The ground-fault circuit must be tested without subjecting the circuit to an actual grounded phase condition. A record of each test must be maintained and made available to authorized representatives of the director and to the miners in such mine.29.14. The diesel generator must be provided with power quality monitoring. This shall include volt meter(s), ammeters and a frequency meter to determine the power quality of all three phases. Table 56-23A
Conductor Size AWG or MGM | Maximum Allowable Circuit Breaker Instantaneous Setting (Ampheres) |
14................ | ...................50 |
12................ | ...................75 |
10................ | ..................150 |
8................. | ..................200 |
6................. | ..................300 |
4................. | ..................500 |
3................. | ..................600 |
2................. | ..................800 |
1................. | ................ 1,000 |
1/0............... | ................ 1,250 |
2/0............... | ................ 1,500 |
3/0............... | ................ 2,000 |
4/0............... | ................ 2,500 |
250............... | ................ 2,500 |
300............... | ................ 2,500 |
350............... | ................ 2,500 |
400............... | ................ 2,500 |
450............... | ................ 2,500 |
500............... | ................ 2,500 |
Table 56-23A
Specifications for portable cables longer than 500 feet
Conductor Size - AWG or MCM | Max. Allowable Length (Feet) | Normal Ampacity at 60° C. Copper Temperature (40° C. Ambient) | Resistance at 60° C. Copper Temperature (Ohms) |
6 | 550 | 50 | 0.512 |
4 | 600 | 70 | .353 |
3 | 650 | 80 | .302 |
2 | 700 | 95 | .258 |
1 | 750 | 110 | .220 |
1/0 | 800 | 130 | .185 |
2/0 | 850 | 150 | .157 |
3/0 | 900 | 175 | .130 |
4/0 | 1,000 | 200 | .116 |
250 | 1,000 | 220 | .098 |
300 | 1,000 | 240 | .082 |
350 | 1,000 | 260 | .070 |
400 | 1,000 | 280 | .061 |
450 | 1,000 | 300 | .054 |
500 | 1,000 | 320 | .050 |
W. Va. Code R. § 56-23-29