W-F-1814-SUP-2 Fuses, Cartridge, High-Interrupting CapacityThis specification covers the general requirements and test procedures for current-limiting and noncurrent-limiting, nonrenewable, cartridge fuses with interrupting capacity ratings of 100,000 or 200,000 rms symmetrical amperes see 3.1 and 6.1.

Pages 1 - 2 - 3 - 4 - 5 - 6 - 7 - 8 - 9 - 10 - 11 - 12 - 13 - 14

W-F-18140

fuses.  The wire connecting the fuseholders, ammeter, and the source of supply shall be in accordance with A-A-

59544 and shall be of the size specified in table V.  For fuses rated at more than 60 amperes, C clamps or suitable clip clamps shall be used to insure adequate contact.  C clamps shall be of iron or steel, weighing not more than 3 ounces and neither face of the clamp in contact with the fuseholder terminals shall have an area exceeding 1/2 square inch.  For fuses rated at 60 amperes or less, a pressure-type fuseholder shall be used to insure adequate contact between the clips and the ferrules of the fuse.

TABLE V.  Wire test leads.

1/  Any connection to the source of supply shall be not

less than 4 feet.

2/  Connections larger than 8 AWG shall employ a suitable soldering lug or pressure wire connector.

4.7.3.2  Class L fuses.  It may be assumed that the temperature has stabilized when three successive readings taken at intervals of 10 percent of the previous elapsed duration of the test, but not less than 10-minute or more than

20-minute intervals, indicate no change.  The temperature during the test shall be made with iron and constantan thermocouples using 30 AWG wires.  Attachment shall be in the center of the fuse terminal approximately .250 inch (6.35 mm) from the outer edge of the fuse body on the side opposite the terminal bus-bar connection.  The fuse

under test shall be bolted to a silver plated copper bus-bar with a rectangular cross-sectional area as specified in table VI.  The bus-bar shall be at least as wide as the terminal or blade of the fuse being tested.  The test current

shall be as specified in table VI.  The equipment shall be calibrated using a dummy fuse substituted for the fuse to be tested.  The dummy fuse shall be a rectangular silver plated copper bus-bar approximately the same length as the fuse to be tested.  The dummy fuse may be one piece or laminated, without space between the laminations.  The

temperature rise of the dummy fuse shall be within the limits specified in table VI.  The thermocouples shall be attached to the dummy fuse at the approximate center and on the side opposite the terminal bus-bar connections.

TABLE VI.  Bus-bar cross-section and dummy fuse temperature rise.

4.7.4  Watts loss (see 3.8).  Fuses shall be mounted in suitable open clip type fuseholders and shall be subjected

to rated current until the temperature is stabilized (see 4.7.3.1).  The voltage drop shall be taken across the geometric

10