UL 248-13:2000 pdf download – Low-Voltage Fuses -Part 13:Semiconductor Fuses.
4 Classification
Semiconductor fuses are non-renewable, They shall provide short-circuit protection and may provide overload protection.
gR — Full-range. overload and short-circuit protection
aR — Partial-range. short-circuit protection.
5 Characteristics
5.2 Voltage rating
For AC, the rating shall be 2000 V ac or less
The DC voltage rating may be different from the AC rating.
5.5 Interrupting rating
For AC, the preferred ratings are 25,000, 50,000. 100,000, or 200.000 A.
For DC. the preferred ratings are 20.000. 50.000, 100.000, 150.000, or 200.000 A.
5.6 Peak let-through current and clearing l2t characteristics
Maximum values of peak let.through current and clearing 12t are provided by the manufacturer. See Clause 8.5.3.
6 Marking
6.1 Marking of fuses
In addition to the marking requirements in Part 1: A semiconductor fuse shall be marked with:
e) the fuse class or classification (See Clause 6.2):
gR (Full-range); or
aR (Partial-range). and
g) the marking Current Limiting may be applied if the fuse complies with the threshold ratio test.
This symbol is optional.7 Construction
7.1 Dimensions
The fuse dimensions are not specified, but shall be in accordance with the manufacturer’s specifications.This specification shall define the envelope shape including length,height,width or diameter,andmounting details.
8.2 Verification of temperature rise and current-carrying capacity8.2.3 Test method
1.0 ln- Temperature rise and current-carrying capacity8.2.4 Acceptability of test results
ln addition to the requirements in Part 1:The maximum temperature rise shall not exceed the following:
Body – Not to exceed maximum continuous temperature rating of material and the value
specified by the manufacturer
Contacts – 130°c
8.3 Verification of overload operation
For gR fuses,the overload operation point and maximum opening time shall be specified by themanufacturer and shall be selected from the following values:
135,150,160,175,200, or 250 percent of rating.
For fuses rated less than 600 A, two samples are to be tested.For fuses rated 600 A and greater,onesample is to be tested.
8.4 Verification of operation at rated voltageAc – Part 1,Table 5
Test 1 – High current specified by manufacturerTest 2 – Maximum energy
Test 3 – Threshold ratio.Required for fuses marked “Current Limiting.”The maximum thresholdratio shall be specified by the manufacturer.
Test 5 – Test to be conducted at a low current specified by manufacturer.Shall not be greaterthan 8o0 percent of the fuse current rating, In-
a) peak let-through currentr and clearing Pt recorded auring Tests 1 and 2;b) fesr circuit frequency shal be recorded; and
c) the maxinum peak arc voltage is specified by the manufacturer.
For DC – Part 1,Table 6
Test 1 – High current specified by manufacturer
Test 2 – Maximum energy
Test 5 – Test to be conducted at a low current specified by manufacturer.Shall not be greaterthan 8o0 percent of rating, ln.