Power Electronics

UL Updates Standard for Supplementary Protectors

Underwriters Laboratories (UL) has issued a new edition of UL 1077, the Standard for Supplementary Protectors for Use in Electrical Equipment. This edition is intended to ensure that UL's standards remain up-to-date with regard to format and editorial issues and to include a Canadian Requirements Comparison Guide (CRG 1077). This new edition also includes revised requirements for the clarification of the Trip-Free Features of Supplementary Protectors; and also clarification of the Calibration Requirements for Multipole Protectors.

These requirements apply to supplementary protectors intended for use as overcurrent, or overvoltage or undervoltage protection within an appliance or other electrical equipment where branch circuit overcurrent protection is already provided or is not required. To be acceptable for use as a component of an end product, the protectors must comply with the following criteria:

The acceptability of a protector in any particular application depends on its ability to be used continuously under the conditions that prevail in actual service. Accordingly, for a particular application a protector may be affected by the requirements for the equipment it is used in, and it may be necessary to additionally evaluate features or performance characteristics that are not specified in this standard.

This standard also covers accessory devices that may be installed in or on the protector to perform a secondary function. Examples of accessories are alarm and auxiliary switches.

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