Errata to Requirements for Conversion of Power Switchgear Equipment
|Publication Date:||19 May 2011|
Present industry conversions involve low- and medium-voltage power circuit breakers used in metal-enclosed and metal-clad switchgear; low- and medium-voltage fused contactors; switchgear vertical sections; power fuse addition or substitution in metal-enclosed interrupter switchgear, and certain ratings of other circuit breakers. This document outlines criteria for conversion of this type of equipment.
This standard cannot detail each test that must be carried out to qualify a conversion. The specific tests shall be selected by the converter considering exact changes made from the previously qualified design. The converter shall conduct thorough and formal design verification for the completed conversion, and shall perform all additional tests determined to be necessary.
A vital part of the circuit breaker conversion process is the electrical and mechanical coordination of the mechanism-operated cell (MOC) switches with the converted circuit breaker to ensure proper operation. New, sealed interrupter modular units may have much less mechanism power than that of the circuit breakers they replace, and may not have the ability to operate all installed MOC switches. Accordingly, this may necessitate substantial revision to or replacement of the MOC switches and their operating linkage in the existing vertical sections to assure proper operation.
Any conversions performed on third-party labeled, or listed equipment, or equipment requiring Nuclear Regulatory Commission conformance will void the label, listing, or certification of the equipment. It will be necessary to reapply to the third party for continued certification of the equipment. For instance, typical examples are: if any UL -listed switchgear assembly is converted to use molded case circuit breakers in place of UL- listed power circuit breakers, the converted switchgear assembly must be submitted to the UL, and if a UL- listed low-voltage power circuit breaker is converted to change the electro-mechanical series trip units to an electronic type trip unit, the converted breaker must be submitted to UL.
A converter shall not knowingly convert a design which he knows to be defective without taking or recommending appropriate action to correct the defect in any assembly being converted.