ANTI PUMPING RELAY WORKING WITH DIAGRAM AND QUESTION AND ANSWER

ANTI PUMPING RELAY WORKING WITH DIAGRAM AND QUESTION AND ANSWER

In this topic i will give you answer 3 question 
1)what is anti pumping relay
2)What is the function of anti pumping relay
3)working of anti pumping relay

1. what is anti pumping relay

anti pimping relay is nothing but like auxiliary relay

2.what is the function of anti pumping relay

• The anti pumping relay primarily prevents the repeated closing signal to the closing coil after successful completion of the closing operation.
• The anti-pumping relay allows the breaker to close only once for each press of the 'close' push button or TNC Switch.If a fault exists on the circuit before the breaker is closed, the breaker will close and immediately trip before the operator has a chance to release the close button (or handle). The anti-pumping relay prevents the still-active close signal from trying to re close the breaker. Many breakers are not rated for multiple successive re close operations. If an anti-pumping relay is not used, the rapid close open-close-open... series can result in destruction of the breaker and harm to the operator.

3.Working of anti pumping relay

fig...1

in this figure 

Positive supply extend to TNC switch. We are pressing the TNC (TRIP NEUTRAL CLOSED) switch to closed position. So positive supply extend to closing coil trough circuit breaker status NC contact and anti pumping relay NC contact.

When closed the circuit breaker contact position has changed see in the fig 2

fig...2

see in the figure circuit breaker status NC contact convert to NO

And  circuit breaker status NO contact convert to NC.

At that time anti pumping relay coil has energized and its contact has changed NO to NC and NC to NO.

Anti pumping is also called Trip Free Mechanism of any Circuit Breaker. Why it is called Trip Free Mechanism?
 

Suppose the Circuit Breaker has been closed by manually by pressing the TNC switch. The operating mechanism will start operating for closing operation.

Meanwhile, a fault has taken place and fault sensing relay gives a trip command to the Circuit Breaker. The Trip Free Mechanism / Anti pumping feature ensures that the Circuit Breaker is tripped by protective relay even if it is under the process of closing.

What will happen if Anti Pumping Relay is not present?

Suppose the Circuit Breaker is closed using TNC switch, and at the same instant the spring of TNC switch fails and it did not come to its NEUTRAL position. So continuos supply will be available to the Breaker closing coil.

Assume a fault occurred and the protection relay had been operated at this instant and opened the CB. Since supply is continuously available to the Circuit Breaker closing coil because of TNC spring failure, then CB will close again, since fault is still persisting the Circuit Breaker will trip. In this way the continuous Circuit Breaker opening and closing will take place which may damage Circuit Breaker operating mechanism.

This phenomenon of continuous Circuit Breaker opening and closing is termed as Circuit Breaker hunting.  That is why to prevent Circuit Breaker hunting, Anti Pumping Relay is used.