Phase sensitivity

US5193043A · kind A · utility

Assignee

• Westinghouse Electric Company LLC · US

Inventors

• Kurt A. Grunert · Beaver, US
• Robert J. Tedesco · Dorpsstraat, US
• John A. Wafer · Beaver, US
• Henry A. Wehrli, III · Monroeville, US
• Lawrence M. Hapeman · Fletcher, US
• Stephen A. Mrenna · Beaver, US

Key dates

• Filing date: Jun 26, 1990
• Grant date: Mar 9, 1993
• Expiry date: Jun 26, 2010

Classification

• Technology area (CPC H): Electricity
• CPC primary: H01H71/7445
• WIPO field: Electrical machinery, apparatus, energy
• WIPO sector: Electrical engineering

Abstract

A multipole circuit breaker, for example, a three pole circuit breaker, can detect a condition when less than all of the phases are open circuited to trip the circuit breaker. This reduces the tripping time and hence risk of damage to the electrical load. The circuit breaker includes a thermal trip unit and a phase sensitivity assembly that is interlocked with the bimetals included with the thermal unit. The phase sensitivity assembly includes one or more levers, responsive to the deflection of a bimetal corresponding to the open circuited phase resulting from cooling action of a bimetal relative to the other bimetals. The relative displacement of the cooling bimetal is used to either trip or reduce the tripping time of the circuit breaker.