UL 248-15:2018-03 Low-Voltage Fuses – Part 15: Class T Fuses

UL 248-15:2018-03 Low-Voltage Fuses – Part 15: Class T Fuses. This Part applies to Class T fuses rated 1200 A or less and 300 or 600 V ac. DC ratings are optional. 4 Classification Class T fuses are non-renewable and current limiting with an interrupting rating of 200,000 A. Each of the voltage ratings, 300 and 600 V ac, is divided into eight body sizes. The maximum current rating l for each size is specified in this Part. Time-delay ratings are optional. 5 Characteristics 5.2 Voltage rating For AC, the rating shall be 300 V ac or 600 V ac in accordance with dimensions shown in Figures A and B. The DC voltage rating may be different from the AC rating. 5.3 Current rating Refer to Figures A and B for range of current ratings in each body size for each voltage rating. 5.5 Interrupting rating For AC — 200,000 A For DC, the preferred ratings are 10,000, 20,000, 50,000, 100,000, 150,000, or 200,000A 8.2.4 Acceptability of test results The maximum temperature rise shall not exceed the following: Contacts Oto 100 A—55°C 101 to600A—75°C 601 to 1200 A — 75°C above equipment calibration temperature 8.3 Verification of overload operation Part 1, Table 4 Test 1 — 1.35 l (Fuses rated 0 — 600 A) Test 2 — 1.5 l (Fuses rated 601 — 1200 A) Test 3 — 2.0 l (Fuses rated 0 — 600 A) Test 5 — 5.0 l for time-delay fuses only 8.4 Verification of operation at rated voltage For AC — Part 1, Table 5 Test 1 —200kA Test 2 — Maximum energy Test 3 — Threshold ratio. The maximum threshold ratio shall be 30. Test 4a — 100 kA Test 4b — 50 kA Test 5a — 3.0 l (Fuses rated 601 — 1200 A) Test 5b — 2.01 I, (Fuses rated 0 — 600 A) 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 Fuses rated 0 — 600 A: Test 2 — Maximum energy Test 5a — 9.0 l for time-delay fuses only.UL 248-15 pdf download.