gujrat technological university chandkheda, Ahmedabad affiliated s.n patel institute of techn

[Audio] Good Morning everyone lets begin the presentation our topic for today is Isolator and Circuit Breaker.

[Audio] Content includes Introduction, need for testing, circuit breaker fundamentals, Test of circuit breaker which includes dielectric test, impulse test, mechanical test, thermal test, short circuit test.

[Audio] While these characteristics are directly relevant to the testing of circuit breakers, they are not much relevant as far as the testing of isolators are concerned since isolators are not used for interrupting high currents..

[Audio] Here are few difference between Isolator and circuit breaker you can go through.

[Audio] During short circuit fault or any other types of electrical fault these equipment suffer a high stress of fault current which may damage the equipment and networks..

Circuit breaker. An Electromechanical switch that breaks the circuit under fault condition. Unlike a fuse , which operates once and then must be replaced , a circuit breaker can be reset to resume normal operation. To detect a fault condition , and immediately discontinue the electrical flow..

TEST OF CIRCUIT BREAKERS. Dielectric tests Impulse tests Mechanical tests Thermal tests ( Temperature rise tests) Short circuit tests.

Dielectric test. Consists of over voltage withstand tests of power frequency , lightning and switching impulse voltages. Tested for internal & external insulation with CB in both the open & closed position. Voltage in open position > 15% of that of closed position. During test , CB is mounted on insulators above ground to avoid ground flash over..

IMPULSE TESTS and thermal test. The test is done with switching over voltage To asses their performance under over voltage due to switching operations THERMAL TEST – To check the thermal behaviour of the breakers Rated current through all three phases of the switchgear is passed continuously for a period long enough to achieve steady state conditions. Temperature rise must not exceed 40 ˚ C when the rated normal current is less than 800 amps and 50˚C if it is 800 amps and above..

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