UL-248-12:2011 pdf free download – STANDARD FOR SAFETY Low-Voltage Fuses – Part 12: Class R Fuses.
8.2.3.1 Fuses rated 600 A or less
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 for a period of not less than 15 mm for fuses rated 0—200 A and not less than 30 mm for fuses rated 201 — 600 A. Temperature is not to be monitored during this time.
8.2.4 Acceptability of test results
In addition to the requirements in Part 1: The maximum temperature rise shall not exceed the following:
Contacts — 100 A: 55°C; >100 A: 75°C.
8.3 Verification of overload operation
Part 1, Table 4
Test 1 —1.35 l
Test 3 — 2.0 l
Test 5 — 5.0 l for time-delay fuses only. For 250 V ac fuses rated 30 A or less, the clearing time may be 8 s minimum.
8.4 Verification of operation at rated voltage
For AC — Part 1, Table 5
Test 1 — 200 kA or 300 kA at the manufacturer’s option.
Test 2 — Maximum energy
Test 3 — Threshold ratio. The maximum threshold ratio shall be 30 for Class RK1 and 65 for Class RK5 fuses.
Test 4a —100 kA
Test 4b — 50 kA
Test 5b — 2.0 l
Peak let-through current and clearing 12t recorded during Tests 1, 4a, and 4b. For DC (optional) — Part 1, Table 6
Test 1 — Interrupting rating
Test 2 — Maximum energy
Test 5a — 9.0 l for time-delay fuses only
Test 5c — 2.0 I
8.5 Verification of peak let-through current and clearing 12t characteristics
8.5.3 Acceptability of test results
Peak let-through currents shall not exceed the levels defined by the appropriate Let Through Function specified in Table A, as verified through measurement of peak let-through currents at 25, 50, 100, 200, and, if applicable, 300 kA. Clearing l2t values recorded shall not exceed the limits specified in Table A as verified through measurement of clearing l2t values at 25, 50, 100, 200, and, if applicable, 300 kA.