UL 248-15-2020 pdf free download.Low-Voltage Fuses – Part 1 5: Class T Fuses.
8 Tests
8.2 Verification of temperature rise and current-carrying capacity
8.2.3 Test method
Fuses rated 0 – 600 A:
1 .0 I n – Temperature rise
1 .1 I n – Current-carrying capacity, I nf
Fuses rated 601 – 1 200 A:
1 .0 I n – Temperature rise and current-carrying capacity, I nf
8.2.3.1 In addition to the requirements in Part 1 : At the conclusion of the temperature rise test, the test current shall be increased without interruption to 1 .1 I n for a period of not less than 1 5 min for fuses rated 0 – 200 A and not less than 30 min for fuses rated 201 – 600 A. Temperature is not to be monitored during this time.
8.2.4 Acceptability of test results
The maximum temperature rise shall not exceed the following:
Contacts
0 to 1 00 A – 55°C
1 01 to 600 A – 75°C
601 to 1 200 A – 75°C above equipment calibration temperature
8.3 Verification of overload operation
Part 1 , Table 4
Test 1 – 1 .35 I n (Fuses rated 0 – 600 A)
Test 2 – 1 .5 I n (Fuses rated 601 – 1 200 A)
Test 3 – 2.0 I n (Fuses rated 0 – 600 A)
Test 5 – 5.0 I n for time-delay fuses only
8.4 Verification of operation at rated voltage
For AC – Part 1 , Table 5
Test 1 – 200 kA
Test 2 – Maximum energy
Test 3 – Threshold ratio. The maximum threshold ratio shall be 30.
Test 4a – 1 00 kA
Test 4b – 50 kA
Test 5a – 3.0 I n (Fuses rated 601 – 1 200 A)
Test 5b – 2.01 I n (Fuses rated 0 – 600 A)
Peak let-through current and clearing I 2 t recorded during Tests 1 , 4a, and 4b.
For DC (optional) – Part 1 , Table 6
Test 1 – Interrupting Rating
Fuses rated 0 – 600 A:
Test 2 – Maximum energy
Test 5a – 9.0 I n for time-delay fuses only
Test 5c – 2.0 I n
Fuses rated 601 – 1 200 A:
Test 5b – (3.0 I n )
or
Test 5c – (2.0 I n )
or
Any current in the range 3.0 I n – 2.0 I n at rated DC voltage
8.5 Verification of peak let-through current and clearing I 2 t characteristics
8.5.3 Acceptability of test results
In addition to the requirements in Part 1 : Peak let-through current and clearing I 2 t values recorded shall not exceed the specified limits in Tables A and B.UL 248-15 pdf download.