To reduce the restriking voltage, RRRV and severity of the transient oscillations, a resistance is connected across the contacts of the circuit breaker. This is known as resistance switching. The resistance is in parallel with the arc.

Besides, On what factor does the rate of rise of restriking voltage?

The rate of rise of re-striking voltage is directly proportional to the natural frequency. So, the rate of rise of re-striking voltage (RRRV) is dependent upon both the inductance and capacitance of the system.

Keeping this in mind, How resistance switching can be used to reduce peak Restriking voltage? If the value of R is so selected that the circuit becomes critically damped then re-strike voltage rises exponentially till recovery voltage is reached. Thus the advantages of resistance switching are as follows: It reduces the rate of rise of re-striking voltage and the peak value of re-striking voltage.

## What is Restriking voltage in circuit breaker?

Restriking voltage is the transient voltage appearing across the breaker contacts immediately after the opening of breaker contacts. also called Transient Recovery Voltage. … Under the influence of this voltage, the arc tries to restrike and hence it is named as the restriking voltage.

## What is prospective voltage?

“prospective” touch voltage [IEV 195-05-09; 826-11-03] • voltage between simultaneously accessible conductive parts. when those conductive parts are not being touched by a person or an animal.

## On which factor does a circuit breaker depends?

Circuit breaker performance depends upon breaking speed, critical length of breaking and also some other factors.

## What is meant by recovery voltage?

It is defined as the voltage appearing across the circuit breaker contacts after the final arc extinction and after all the transients die out (or disappears). As a result the final arc extinction takes place and circuit current is interrupted. …

## What is fusing factor Mcq?

Fusing factor is defined as the ratio between. a) Maximum fusing current and rated voltage.

## How does resistance switching prevent excessive voltage surge during circuit break?

When the fault occurs, the contacts of the circuit breaker are open, and an arc is struck between the contacts. … It reduces the RRRV ( Rate of Rising of Restriking Voltage ) burden on the circuit breaker. It reduces the high-frequency restriking voltage transients during switching out inductive or capacitive loads.

## Why the resistance switching is used in air blast circuit breaker?

Resistance switching: It is a method adopted for dampening the over-voltage transients due to current chopping. In this method, a shunt resistance is connected across the contacts of the circuit breaker. It reduces the rate of rising of re-striking voltage and the peak value of re-striking voltage.

## How current chopping phenomena can be rectify by using resistance switching?

The switching Resistor (R) is connected in parallel with the CB contacts. Current chopping produces high voltage oscillations which can be prevented by this method. … Since R is in parallel with Cb contacts ,a part of arc current flows through this resistance so arc current decreases and deionization rate increases.

## What is voltage transient?

What are voltage transients? A transient voltage is a temporary unwanted voltage in an electrical circuit that range from a few volts to several thousand volts and last micro seconds up to a few milliseconds. … Faulty contactors and lightning are the most common source of transients.

## What is the difference between Restriking voltage and recovery voltage?

At which Voltage level restrike of ARC occurs is called as restriking Voltage. … The normal frequency (60 Hz) r.m.s. voltage that appears across the contacts of the circuit breaker after final arc extinction in the steady state is the recovery voltage and is equal to the system voltage.

## What is prospective touch voltage?

‘Touch voltage’ is a term which does not appear in BS 7671, but the term ‘Prospective Touch Voltage’ is defined in the International Electrotechnical Vocabulary as ‘Voltage between conductive parts when those parts are not being touched by a person or an animal’.

## What is meant by prospective fault current?

Prospective Fault Current (PFC) is the common term used for the highest amount of current that will stream under fault conditions. The PFC will continuously be the highest at the source of the installation as the impedance/resistance is always the lowest there.

## What is prospective current of fuse?

Prospective Current in Fuse

The prospective current is defined as the value of current which would flow through the fuse immediately after a short circuit occurs in the network.

## What do circuit breakers protect?

A circuit breaker is an electrical switch designed to protect an electrical circuit from damage caused by overcurrent/overload or short circuit. Its basic function is to interrupt current flow after protective relays detect a fault.

## What should be the value of fusing factor?

This is the ratio of minimum fusing current and current rating of fuse. Therefore, fusing factor = Minimum fusing current or current rating of the fuse. The value of fusing factor is always more than 1.

## What is breaking capacity of circuit breaker?

Breaking capacity or interrupting rating is the current that a fuse, circuit breaker, or other electrical apparatus is able to interrupt without being destroyed or causing an electric arc with unacceptable duration.

## What is recovery voltage in power system?

Recovery Voltage:

Recovery Voltage is the normal frequency RMS voltage that appears across the contacts of the Circuit Breaker after final arc extinction. It is equal to the system voltage.

## What is circuit breaker recovery voltage?

The recovery voltage is the voltage which appears across the terminals of a pole of circuit breaker after current interruption.

## What is reverse recovery voltage?

When the voltage across a diode is suddenly reversed, an initial current flow will occur in the reverse direction. Reverse recovery time (Trr) is the time taken to stop conducting when the diode is reverse biased.

## What is fusing factor?

Fusing factor. It is the ratio of minimum fusing current and current rating of the fuse. Minimum fusing current is the minimum value of current due to which fuse melts. The current rating of fuse is the maximum value of current due to which fuse does not get melt.

## What is the fusing current?

Fusing current: It is the minimum current at which the fuse element melts and thus disconnects the circuit protected by it. Obviously, its value will be more than the current rating of the fuse element.

## What should be value of fusing factor?

This is the ratio of minimum fusing current and current rating of fuse. Therefore, fusing factor = Minimum fusing current or current rating of the fuse. The value of fusing factor is always more than 1.