Resistance Switching in Circuit Breaker

Resistance Switching in Circuit Breaker refers to a method adopted for dampening the over voltage transients due to current chopping, capacitive current breaking etc. In this method, a shunt resistance is connected across the contacts of circuit breaker. How does Resistance Switching Work? Let us consider a circuit and connect a shunt resistance R across … Read more

What is Endurance Test of Circuit Breaker?

Endurance Test of Circuit Breaker is conducted to check the healthiness of its mechanical parts i.e. operating mechanism. In this test, Circuit Breaker is operated several times and checked for any damage of its mechanical parts / contacts. The breaker should be in a position to open and close satisfactorily. This test is also called … Read more

Rated Normal, Short Circuit Making & Breaking, Short Time Current Rating & Operating Duty Cycle of Circuit Breaker

Rated Normal Current: The rated normal current of a circuit-breaker is the r.m.s. value of the current which the circuit breaker can carry continuously and with temperature rise of the various parts within specified limits. The design of contacts and other current carrying parts in the interrupter of the circuit breaker are generally based on … Read more

Concept of Subtransient, Transient & Steady State

The concept of Subtransient, Transient and Steady State arises in case of fault in an Alternator. Let us assume a sudden short circuit in three phase of alternator. The fault current will flow in all the three phases of alternator and its waveform will be as shown in figure below. When the alternator is short-circuited, … Read more

Circuit Breaker and Arc Phenomenon

What is Circuit Breaker? Circuit Breaker is switch capable of making or breaking the circuit under no-load as well as on-load condition. It can make or break circuit either manually or by remote control. A Circuit Breaker in conjunction with Relay can break the circuit under fault condition. You may also like to read,┬áBasic Principle … Read more

Why Making Current of Circuit Breaker is more than Breaking Current?

To understand this aspect making current and breaking current, first we should know what actually the making current and breaking current signifies in context with Circuit Breaker. Making Current of a Circuit Breaker is the peak value of maximum current loop during subtransient condition including DC component when Breaker closes. In the figure below, I1 … Read more

Difference between Isolator and Circuit Breaker

Isolator and Circuit Breaker both are switches to isolate a section of power system. But Isolator is off load device whereas Circuit Breaker is on load device. Off load device means, Isolator cannot be operated when load is connected i.e, current is flowing through the circuit. Therefore, Isolator shall only be operated when that circuit … Read more