Selective DC Scheme in Breaker Control Circuits

The Selective DC Scheme in circuit breaker control circuits is a specialized design used to enhance reliability and ensure fail-proof operation in power system protection and control. In a Selective DC Scheme, multiple (normally two) DC supplies are taken to ensure that control circuit of CB remains functional even if one of the supplies fails. … Read more

Understanding the Anti-Pumping Scheme in Circuit Breakers

In electrical power systems, circuit breakers play a crucial role in protecting equipment and ensuring the stability of the grid. However, improper operation of breakers can lead to major fault and unsafe conditions. One critical issue in breaker operation is multiple closing attempts before clearing a fault. This can occur due to a continuous closing … Read more

Top Interview Questions and Answers on 33KV Circuit Breaker

What type of circuit breaker is generally used for the 36KV class ?Ans: The 36KV class circuit breaker is normally an outdoor type Vacuum Circuit Breaker (VCB). Why is VCB Preferred in 33KV Outdoor Systems Over SF6 Circuit Breakers?Ans: VCBs are more economical for 33KV systems compared to SF6 circuit breakers due to simpler construction … Read more

Rated Transient Recovery Voltage of a Circuit Breaker

A high voltage circuit breaker plays a crucial role in power systems by protecting electrical equipment from damage due to electrical faults in the system. One of the key challenges in circuit breaker design is dealing with the transient recovery voltage (TRV), a phenomenon that occurs immediately after current interruption. When a fault current gets … Read more

Duty Cycle of a Circuit Breaker

A Circuit breaker is an essential component in electrical power system. It is designed to interrupt fault currents and hence protect equipment from damage. A crucial aspect of their performance is the duty cycle. The duty cycle defines the operational requirements and limitations of the breaker in terms of repeated opening and closing operations. Whenever … Read more

High Voltage Circuit Breakers (HVCBs)

What is a High Voltage Circuit Breaker? A High Voltage Circuit Breaker (HVCB) is a crucial component in power transmission and distribution networks. Its primary role is to protect electrical equipment by interrupting fault currents within the system. Beyond safeguarding equipment, HVCBs are vital for maintaining the integrity of the power grid. They isolate faults … Read more

Zero Current Crossing Method in A Circuit Breaker

This zero current crossing method is only applicable to alternating current circuit breaker. We all know that an alternating current naturally passes through zero at regular intervals (every half-cycle of the AC waveform). This method safely interrupts the alternating current at the natural zero-crossing of its waveform. Working Principle of a CB based on Zero … Read more

Details Current Ratings of a Circuit Breaker

In addition to the normal current rating of a circuit breaker (which is the current it can handle continuously during regular operation), there are two important categories of short-circuit current ratings that define how the circuit breaker performs during fault conditions: Rated Short Circuit Breaking Current The short-circuit breaking current of a circuit breaker consists … Read more

Testing of a Vacuum Circuit Breaker

Type Tests for a 36kV Class Vacuum Circuit Breaker (VCB) As per IS: 13118, these type tests include: These tests are intended to ensure that the circuit breakers perform reliably, safely, and efficiently under various operating conditions. Routine Tests for a 36kV Vacuum Circuit Breaker (VCB) As per IS: 13118, the routine tests include the … Read more