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Solid State Overcurrent Protectors
1.1 This standard covers solid-state overcurrent protectors. These devices are solid-state switches that limit the output current to a safe level when the output load exceeds the current-limit threshold or when a load-side short-circuit is present. Solid-state overcurrent protectors are intended to be used on the load-side of an isolating transformer, power supply or battery to provide a means of supplementary protection. See Table 1.1 for maximum current and power levels.
1.2 The devices covered by these requirements are integrated circuits, and electrical spacings within the devices are not specified.
1.3 The devices covered by these requirements are entirely electronic in nature and have no means for manual operation or reset.
1.4 The terminals of the devices covered by these requirements are for factory wiring only (intended to be mounted on a printed wiring board).
1.5 The devices covered by these requirements shall only be used on supply circuits originating from an isolating transformer, a power supply or a battery with limited maximum current and power levels as noted in Table 1.1. Use on supply circuits with a higher power capability requires additional evaluation for reliability, such as those requirements contained in the Standard for Safety-Related Controls Employing Solid-State Controls, UL 991.
1.6 The devices covered by these requirements limit output currents to values less than the overcurrent protection rating of 5 amperes.
1.7 The devices covered by these requirements have only been evaluated for supplementary overcurrent protection of secondary circuits supplied by the load side of a transformer, power supply or battery and have not been evaluated for branch-circuit protection.
1.8 This standard may cover devices intended for use in telecommunications applications. However, devices intended for connection to telecommunications networks with outside plant connections should be evaluated in the end-use in accordance with the requirements of the Standard for Information Technology Equipment Safety – Part 1: General Requirements, UL 60950-1, or the Standard for Secondary Protectors for Communication Circuits, UL 497A, as appropriate.