UL 248-1-2017 pdf free download

UL 248-1-2017 pdf free download.LoW-Voltage Fuses – Part 1 : General Requirements.
Measurement of temperatures shall be by thermocouples. The thermocouples shall be secured by Fuller’s earth and waterglass. welding, soldering, or other method that provides thermal contact.
The thermocouples shall consist of iron and constantan or chromel and alumel wres not Iarge than No. 24 AWG (021 mm2).
An alternative method of temperature measurement may be used 1 upon investigation it is shown that the alternative method provides equivalent results.
8.23.1 Fuses rated 600 A or less
Fuses rated 600 A or less shall carry 1.0 I,, until temperature stabilization occurs.
Stabilization shall be considered to have occurred when no individual temperature nse reading of 4 consecutive readings taken at 5 mm intervals exceeds the average reading of these 4 readings by more than 2°C and no indication of increasing temperature rise Is observed. This average temperature rise reading shall be deemed to be the temperature rise of the fuse.
Thermocouples shall be placed against the center of the top or upper surface of the fuse — midway between the caps or ferrules on the body and on each ferrule or blade at the top center of the fuse clip.
8.2.3.2 Fuses rated 601 — 6000 A
Fuses rated more than 600 A shall carry 1.1 I until temperature stabilization occurs.
Stabilization shall be considered to have occurred when no individual temperature rise reading of 4 consecutive readings taken at 10 mm intervals exceeds the average reading of these 4 readings by more than 2°C and no indication of increasing temperature rise is observed This average temperature rise reading shall be deemed to be the temperature flse of the fuse.
The test equipment shall be calibrated, with a shorting bar substituted for the fuse to be tested, to produce a temperature rise on the shorting bar within the limits specified in Table 3.
The shorting bar shall be the same length as the fuse for which it is substituted. The cross-sectional dimensions of the shorting bar shall be the same as those of the bus bar. The shorting bar shall be of copper, shall be silver-plated at the terminal connections, shall have holes to permit mounting to the bus bar, and shall be one-piece or laminated without space between the laminations.
During calibration, a thermocouple shall be located at the top center of the shorting bar.
During the temperature test, a thermocouple shall be secured at the top center of each fuse contact. approximal&y 6.4 mm (1/4 In) from the end of the fuse body.UL 248-1-2017 pdf free download.