Miniature Circuit Breaker (MCB) CJM2-125

CJM2-125 miniature circuit breaker(MCB) is mainly used for protection against overload and the short circuit under the AC 50Hz/60Hz, rated voltage 230V/400V and rated current from 20A to 125A. It also can be used for non-frequent on-and-off switch operation under normal circumstances. Circuit breakers are mainly used in industrial, commercial, high-rise buildings, household and other places.

Products Details

Construction and Feature

  • High short-short capacity 10KA
  • Designed to protect circuit carrying big current up to 125A
  • Contact position indication
  • Used as main switch in household and similar installation
  • The price-quality ratio is very high


Standard IEC/EN 60898-1
Pole No 1P,1P+N, 2P, 3P,3P+N,4P
Rated voltage AC 230V/400V
Rated Current(A) 20A,25A,32A,40A,50A,63A,80A,100A,125A
Tripping curve C, D
Rated short-circuit capacity(lcn) 10000A
Rated service short-circuit capacity(Ics) 7500A
Rated frequency 50/60Hz
Rated impulse withstand voltage Uimp 6kV
Connection terminal Pillar terminal with clamp
Electro-mechanical endurance Ins100=10000:n125=8000
Terminali Connection Height 20mm
Connection capacity Flexible conductor 35mm²
Rigid conductor 50mm²
Installation On symmetrical DIN rail 35mm
Panel mounting

Overload Current Protection Characteristics

Test Tripping Type Test Current Initial State Tripping timeor Non-tripping Time Provisior
a Time-delay 1.05In Cold t≤1h(In≤63A) t≤2h(ln>63A) No Tripping
b Time-delay 1.30In After test a t<1h(In≤63A) t<2h(In>63A) Tripping
c Time-delay 2In Cold 10s<t<60s(In≤63A) 20s<t<120s(In>63A) Tripping
d Instantaneous 8ln Cold t≤0.2s No Tripping
e lnstantaneous 12In Cold t<0.2s Tripping

Working Principle of MCB

When an MCB is subject to continuous over-current, the bimetallic strip heats up and bends. An electromechanical latch is released when the MCB deflects the bi-metallic strip. When the user connects this electromechanical clasp to the working mechanism, it opens the microcircuit breaker contacts. Consequently, it causes the MCB to switch off and terminate the current flowing. The user should individually switch on the MCB to restore the current flow. This device guard against defects caused by excessive current, overload, and short circuits.

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