The transient voltage appear across the contacts of circuit breaker at current zero period during arcing is known as Restriking voltage. The rate of rise of re-striking voltage is directly proportional to the natural frequency.
What will be happened if Restriking voltage is not removed quickly? It is also called Transient Recovery Voltage (TRV). Restriking voltage is associated with high frequency which die out quickly. … If the rate of rise of dielectric strength of medium is less than the restrining voltage, arc quenching will not take place and hence fault will not be interrupted.
Similarly, How does Restriking voltage affect arc interruption process in circuit breakers? Voltage Race Theory
If we remove ions at the initial stage either by recombining them into neutral molecules or inserting insulation at a rate faster than the rate of ionization, the arc can be interrupted. The ionization at zero current depends on the voltages known as restriking voltage.
What is the average rate of rise of restriking voltage up to the first peak is?
The average rate of rise of re-striking voltage upto first peak is. A 50 Hz, 11 kV, 3-phase alternator with earthed neutral has reactance of 7 ohms per phase and is connected to bus-bar through a circuit breaker.
How do you reduce Restriking voltage?
To reduce the restriking voltage, RRRV and severity of the transient oscillations, a resistance is connected across the contacts of the circuit breaker. To reduce the restriking voltage, RRRV and severity of the transient oscillations, a resistance is connected across the contacts of the circuit breaker.
On what factor does the rate of rise of restriking voltage depends?
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.
What is current chopping? Current chopping is the condition where during an ac current interruption the current becomes unstable as it approaches a zero crossing and stops before the zero is reached. Current chopping occurs to some degree in all types of interrupters.
What is low resistance or current zero method? Low Resistance or Current zero Method
This method is employed for arc extinction in AC Circuits only. In this method, arc resistance is kept low until current zero where the arc extinguishes naturally and is prevented from restriking inspite of the rising voltage across the contacts.
On what factor does the rate of rise of restriking voltage depend?
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.
What is average RRRV in circuit breaker? and the RRRV is below 1.54kV/µs. Current Chinese and IEC EHV/UHV CB standard, requires CB’s to withstand a TRV peak value of 2.5 p.u. and RRRV of 1.54 kV/µs when interrupting 25 % of rated breaking current.
How is the Restriking voltage considered Mcq?
ANSWER: a. The transient voltage that appears across the circuit breaker contacts at the instant of arc extinction.
What is the average rate of rise of restriking voltage upto the first pic?
| Q. | What is the average rate of rise of restriking voltage upto the first peak? |
|---|---|
| B. | 453 * 103kV / sec |
| C. | 582 * 103 kV / sec |
| D. | 467 * 103 kV / sec |
| Answer» b. 453 * 103kV / sec |
What is the Restriking voltage Mcq?
Q1. What is restriking voltage? … The transient voltage that appears across the circuit breaker contacts at the instant of arc extinction.
What is the major drawback of using SF6 circuit breakers?
Sealing problems of the gas. Ingress of moisture in the gas system – dangerous. Deterioration of SF6 gas with time.
What measures are taken to reduce Restriking voltage and RRRV? 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.
What is current zero?
Current zero (CZ) refers to the interruption phenomena in high power circuit-breakers. Today it seems improbable that high voltage circuits could be interrupted economically by other means than the electric arc. … The current zero phenomena is an indicator for the pressure, temperature, ion density, plasma flow, etc.
How many types of ACB are there?
There are mainly two types of ACB are available. Plain air circuit breaker. Air blast Circuit Breaker.
What is the difference between ACB and VCB? ACBs are used for low voltage application below 690Volts or it industry level it is called as LT application (Low tension), VCB are used for medium voltage application such as below 33kV and SF6 circuit breakers are used in high voltage application as well as medium voltage application.
What is high resistance method?
Two methods are used to measure high resistance, the constant voltage method and the constant current method. … In the constant current method, a constant current is forced through the unknown resistance and the voltage drop across the resistance is measured.
What is Cassie’s theory? Cassie’s law, or the Cassie equation, describes the effective contact angle θc for a liquid on a chemically heterogeneous surface, i.e. the surface of a composite material consisting of different chemistries, that is non uniform throughout.
What is meant by arc interruption?
Arc is a phenomenon occurring when the two contacts of a circuit breaker separate under heavy load or fault or short circuit condition.
Why is current interruption easier in an AC circuit than in a DC circuit? Since the current in AC passes through zero it is easier to break the arcing or it gets self extinguished while DC has a constant current, it causes large spark or arc then the conductors have to move away far or cut the power supply. So interrupting a fault is easier in AC but difficult in DC.