Publication detail

Diagnosis of heat loss in the molded case circuit breaker contacts in nominal current

DOSTÁL, L. MEJZLÍK, T.

Original Title

Diagnosis of heat loss in the molded case circuit breaker contacts in nominal current

Type

conference paper

Language

English

Original Abstract

The paper deals with an analysis of temperature on the rotary breaking system of a molded case circuit breaker. Molded case circuit breaker has a modern breaking me-chanism with uses rotary breaking system. The main makes contact move along circular path. The current path is interrupted in two places where some thermal losses rise in running order. The size of the thermal losses depends on the transient resistance. System of springs is used for eliminating the transient resistance between contacts. The right setting force of these springs is important for right function of the thermal release. In the opposite case the nominal current can be incorrectly evaluated and the circuit breaker turn off at the wrong time. Thermal losses are computed using finite element method (FEM). The first part of the paper focuses on the calculation of the thermal losses of the current path in nominal current 630 A. The contact force changes from 20 to 100 N. The second part of the paper focuses on laboratory measurement to verify thermal calculations. The results of laboratory measurement confirms the accuracy of the finite element method. The optimum power of the pressure springs should be 45-60 N. In this setting springs the thermal losses do not affect the right function of the thermal release and extend the mechanical life of the circuit breaker.

Keywords

Circuit breaker, contact resistance, FEM, heat loss, Joule heating, laminar flow, Molded Case Circuit Breaker (MCCB), temperature rise, thermal flow

Key words in English

Circuit breaker, contact resistance, FEM, heat loss, Joule heating, laminar flow, Molded Case Circuit Breaker (MCCB), temperature rise, thermal flow

Authors

DOSTÁL, L.; MEJZLÍK, T.

RIV year

2012

Released

23. 5. 2012

Publisher

Brno University of Technology

Location

Brno

ISBN

978-80-214-4514-7

Book

Proceedings of the 13th International Scientific Conference Electric Power Engineering 2012

Edition

Vol. 1

Edition number

1

Pages from

911

Pages to

915

Pages count

5

BibTex

@inproceedings{BUT91832,
  author="Lukáš {Dostál} and Tomáš {Mejzlík}",
  title="Diagnosis of heat loss in the molded case circuit breaker contacts in nominal current",
  booktitle="Proceedings of the 13th International Scientific Conference Electric Power Engineering 2012",
  year="2012",
  series="Vol. 1",
  number="1",
  pages="911--915",
  publisher="Brno University of Technology",
  address="Brno",
  isbn="978-80-214-4514-7"
}