UL 4248-12:2012 free download

UL 4248-12:2012 free download Fuseholders – Part 1 2: Class R
1.1 Scope
1 .1 .2 These requirements cover fuseholders intended for use with Class R Fuses as described in NMX-J-009/248/1 2-2000-ANCE, CSA C22.2 No. 248.1 2, UL 248-1 2, Low-Voltage Fuses – Part 1 2: Class R Fuses.
4 Classification
4.1 Class R fuseholders have a short-circuit withstand rating of 200,000 A. Class R fuseholders are rated 250 V or 600 V, and are divided into six body sizes in each voltage rating corresponding to the Class R fuse body sizes.
5 Characteristics
5.1 Summary of characteristics
5.1 .3 Voltage and current rating
5.1 .3.1 Class R fuseholders shall be rated 250 V or 600 V.
5.1 .3.2 Class R fuseholders shall be rated 30, 60, 1 00, 200, 400, or 600 A.
5.1 .4 Withstand rating
5.1 .4.1 Class R fuseholders shall have a short-circuit withstand rating of a 200,000 A.
6 Marking
6.1 Marking of fuseholder
6.1 .1 .1 In addition to the requirements of Part 1 , the fuseholder shall be marked ″Use Class R Fuses″.
7 Construction
7.6 Contacts of a cartridge fuseholder
7.6.1 The dimensions of a Class R fuseholder shall be as specified in Figure 7.6A or 7.6B, whichever is applicable. Class R fuseholders shall be provided with a rejection member to prevent the installation of fuses of other classes.
8 Tests
8.1 General
8.1 .1 Types of tests
8.1 .1 .1 .1 Each fuseholder shall be subjected to the tests as specified in Part 1 , with the addition of the following:
e) verification of effectiveness of rejection member.
8.4 Verification of temperature rise
8.4.3 Test method
8.4.3.1 With dummy fuses in place and carrying rated current continuously, the temperature on a material or component or electrical insulation shall not exceed the values in Table 8.4B.
8.4.3.2 Dummy fuses shall be unplated copper and shall conform to the dimensions in Table 8.4A.
8.4.3.3 The temperatures specified in Table 8.4B are based on an assumed ambient temperature of 25°C (77°F). A test may be conducted at an ambient temperature within the range of 20 – 40°C (68 – 1 04°F).
8.4.3.4 During a test conducted at an ambient temperature of 25°C (77°F), an observed temperature shall not exceed the required value specified in Table 8.4B.
8.4.3.5 If a test is conducted at an ambient temperature other than 25°C (77°F), an observed temperature shall be corrected as described in Clause 8.4.3.6. Neither a corrected temperature nor an observed temperature shall exceed the required value specified in Table 8.4B.
8.4.3.6 An observed temperature shall be corrected by addition [if the ambient temperature is lower than 25°C (77°F)] or subtraction (if the ambient temperature is higher than 25°C) of the difference between 25°C and the ambient temperature.
8.4.3.7 If a corrected temperature exceeds the required value specified in Table 8.4B, at the request of the manufacturer, the test may be repeated at an ambient temperature closer to 25°C (77°F).