NEMA C37.50

Abstract

This standard covers the test procedures for enclosed low-voltage ac power circuit breakers as follows: <br>a) Stationary or drawout circuit breakers of two-or three- or four-pole construction, with one or more rated maximum voltages of 635 V (600 for units incorporating fuses), 508 V, and 254 V for application on systems having nominal voltages of 600, 480, and 240 V. <br>b) Unfused or fused type circuit breakers <br>c) Manually operated or power-operated circuit breakers with or without electromechanical or solid-state trip devices. <br>d) Fused drawouts consisting of current-limiting fuses in a drawout assembly intended to be connected in series with a low-voltage ac power circuit breaker to form a non-integrally fused circuit breaker. <br><em>Note:</em> In this standard the term circuit breaker shall mean enclosed low-voltage ac power circuit breaker, either fused or unfused. The term unfused circuit breaker shall mean a circuit breaker without either integrally or non-integrally mounted fuses, and the term fused circuit breaker shall mean a circuit breaker incorporating either integrally or non-integrally mounted current limiting fuses. <br>This document applies to both integrally and nonintegrally fused circuit breakers.