Sidactor Protection Thyristor Products Page 59 SIDACtor Protection Thyristor Products

SIDACtor Protection Thyristors 2017 Littelfuse, Inc. Specifications are subject to change without notice. Revised: 02/23/17 UL 497D covers secondary protector components for communications circuits located on the equipment side of a primary protector, also known as the protected side of the circuit. With a few exceptions, these devices shall also comply with all the requirements of UL 497A. These components provide voltage and/or current surge protection after the primary protector but "these components do not normally provide protection for the voltage suppression device needed in the circuit to limit the voltage to less than the component ratings." It will limit current to the capacity of the protected wiring, however; they do not provide protection against excessive currents that may flow during the operation of the primary protection device. Thus, additional overcurrent protection prior to the voltage suppression device may be required. The overvoltage test of UL 497A, Section 27, are to be performed using a reduced test voltage based on the voltage ratings of the component being tested. These tests are: a) Test L1 - @ Voltage rating of device, 40A, 1.5 S. b) Test L2 - @ Voltage rating of device, 7A, 5 S. c) Test L3 - @ Voltage rating of device, 2.2A, 30 M (and 1.0A, 0.5A, & 0.25A) d) Test L4 - 200V, 2.2A, 30 M or, when the equipment contains voltage-limiting devices operating between 200 and 600 volts AC, and the secondary protector employs other components that can be affected by the fault; at a voltage value just below the breakdown point of the overvoltage device is to be used. When the secondary protector contains current interrupting devices operating below 2.2 amperes, a current value just below the interrupting point of such device is to be used. This test is conducted for a minimum of thirty minutes. The test may be ended when during the trial it can be verified that the sample has mechanically disconnected the test current as described for Test L3. Compliance with this test is based on the following conditions being met: a) There shall be no ignition or charring of the cheesecloth indicator. b) Based on the wiring simulator that is used: 1) The fuse or device used as the wiring simulator (MDQ 1-6/10) shall not interrupt the current during the test or 2) When a No. 26 AWG (0.13 mm2) solid copper wire is used as the wiring simulator, it shall not fuse open and shall not cause ignition or charring of the cheesecloth indicator. c) The secondary protector shall comply with the Dielectric Voltage-Withstand Test: 1) one minute, without breakdown, the application of 40-70 Hz AC, between live parts and the enclosure; live parts and exposed dead-metal parts; and live parts of circuits operating at different potentials or frequencies. The test potential shall be: a) For a unit rated 30 volts AC rms (42.2 volts AC peak) or less - 500 volts b) For a unit rated between 31 and 150 volts AC rms - 1000 volts Regulatory Requirements (continued) UL 497D

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