UL 198M:2003 pdf download Mine-Duty Fuses
1.1 These requirements cover Class K and Class R fuses having an additional D-C rating and that areintended for use in protecting trailing cables in D-C circuits in mines in accordance with the requirementsof the United States Department of Labor, Mine Safety and Health Administration.
1.2 These fuses have a maximum current rating of 600 A, a voltage rating of 300 or 600 V dc, and aninterrupting rating of 20,000 A dc.
2 General
2.1 ln addition to the requirements in this standard, a fuse shall comply with all of the requirements forthe respective fuse Class in:
a) The Low-Voltage Fuses – Part 9: Class K Fuses, UL 248-9; or
b) The Low-Voltage Fuses – Part 12: Class R Fuses, UL 248-12.
3 Units of Measurement
3.1 Values stated without parentheses are the requirement. Values in parentheses are explanatory orapproximate information.
4Undated References
4.1 Any undated reference to a code or standard appearing in the requirements of this standard shall beinterpreted as referring to the latest edition of that code or standard.
PERFORMANCE
5 General
5.1 Samples of the fuses are to be subjected to the D-C tests specified in Table 5.1.
5.2 Sets of fuses, 5 samples in each set, of the maximum rating of each case size are to be selected.one set for each of the four applicable tests specified in Table 5.1. lf the internal features change at someintermediate rating in a particular fuse case size, this fact is to be considered and additional test sets areto be selected so that each construction is subjected to the complete test program.
5.3 Samples from each set are to be temperature and humidity conditioned prior to testing. A test is to beperformed within one hour after removal of the samples for the test from the conditioning environmentThe conditioning is to be as follows:
a) Temperature – Two samples from each set are to be conditioned in an air oven at 90 +3°C(194 +5.4°F) for a minimum of 24 hours.
b) Humidity – Three samples from each set are to be conditioned at a relative humidity of 95+5 percent at 25 +5°C (77 +9°F) for a minimum of five days.
5.4 At least three fuses from each set are to be tested in a fuseholder of the trolley-tap type. One fuse isto have been temperature conditioned and two fuses are to have been humidity conditioned.
5.5 A fuse not tested in a fuseholder of the trolley-tap type, is to be clamped in place or mounted, with orwithout clamps, in fuse clips spaced to fit the fuse, and tested in open air.
5.6 The test circuit is to consist of series connected inductors and resistors. An inductor is not toincorporate a ferromagnetic core.
5.7 The open circuit voltage for the test circuit is to be not less than 100 percent and not more than 110percent of the rated voltage of the fuse.
Exception: A higher voltage may be used if agreeable to those concerned.
5.8 The test current is to be measured at the terminals of the fuseholder with the terminals short-circuitedby a bus bar or other connection of negligible impedance.
5.9 The test curent is to be determined by measuring the maximum displacement on an oscillogram ata time, after the start of current, of not less than 4 times the circuit time constant. Any overshoot abovethe time-current curve (exponential curve) is not to be considered. An ammeter (and shunt) may be usedfor currents up to 1800 A