Circuit Breaker Part 1: Technical specifications (Tests)

Circuit Breakers are the switching and current interrupting devices

A Circuit breaker (CB) three main parts:

• Fault current interruption.
• Arc extinction
• Speed of operation

CB has fixed and movable contacts. Contacts can be operated by an operating mechanism.

Separation of current-carrying contacts produces the arc, the arc is extinguished by suitable media such as Dielectric oil, Air, SF6 gas and Vacuum.

Arc is extinguished by lengthening, compression, cooling, splitting or rotation. 

Tests:

Type tests (design tests) and Routine tests (production tests) are required by Standards.

Type tests are performed only once on one representative test object in accordance with applicable standards and are not repeated without extra charge. The purpose of the type tests is to verify the ratings of the design.

Routine tests Before delivery routine tests are performed in accordance with applicable standards on each circuit breaker. The purpose of the routine tests is to verify the assembly and the function on every individual circuit breaker. Routine test certificates are sent to the user with each delivery.

Type tests:

• Mechanical performance test, 
• Thermal test, 
• Dielectric or insulating test, 
• Short circuit test for checking the making capacity, Breaking capacity, 
• Short time rating current 
• Operating duty

Routine tests:

• Nameplate and design check
• Resistance measurement (components in auxiliary and control circuits)
• Function check of auxiliary and control circuits
• Mechanical operating test
• Resistance measurement (main circuit)
• Dialectical test (auxiliary and control circuit)
• Overpressure test
• Dielectrically test (main circuit)
• Tightness test