Electrical systems have different control mechanisms in various equipment. It has protection, switching, controlling, measuring, and many other devices to perform their function. In this article, we will discuss an anti-pumping relay in a circuit breaker. Let’s get into it!
Anti-Pumping Relay:
An anti-pumping relay is used in the mechanism box of the circuit breaker to ensure the sending of a closing command to the circuit only once and avoid sending the closing command to the circuit breaker again at the same time.
We use TNC switches in circuit breakers to manually trip, neutral, and close. This switch has three positions as you can see in the following image:
A TNC switch contains a spring that brings back the needle to a neutral position after closing or tripping the circuit breaker manually using this switch due to the operation of the same spring inside it. But in case of malfunctioning of this TNC switch, the spring may send a large number of close or trip commands to the circuit breaker. This is a severe condition that can harm the circuit breaker by closing or opening its contacts multiple times at a time due to the unwanted functioning of the TNC switch.
To avoid this unwanted situation in the circuit breaker we use an anti-pimping relay. Anti-pumping relay prefers to trip in case of fault even if we send a closing command via a TNC switch. In case of spring failure in the TNC switch, at a time closing and tripping (fault case) commands will occur in the circuit breaker. This can affect the closing and tripping coil in the circuit breaker. This is also called circuit breaker hunting as multiple commands are going in the circuit breaker at a time.
Control Circuit of circuit breaker:
Now we will discuss the control circuit if closing and tripping circuit breaker. It operates via a 110/220V DC supply. Two lines above and below the diagram are showing DC supply.
Here you can see the control of the circuit break:
When you push the push button, the supply will go down to NC contact to the closing coil of the circuit breaker. Similarly in case of a fault relay will sense that fault and will send a signal to the contacts of the tripping coil of the circuit breaker.
But in case of a faulty push button supply will continue to go down to the NC contact of the auxiliary contact of the circuit breaker and hence at a time relay will be sending a tripping command due to fault and at the same time the push button will be sending the supply to closing coil (due to its mal-functioning). This will cause the tripping and closing and this situation is called pumping in the circuit breaker.
Note:
NC auxiliary contact is there to check the status of a circuit breaker, whether it is in close condition or an open position. This contact is NC by default and when the circuit breaker is in open condition it will close its contact and vice versa.
Working of Anti Pumping relay:
Imagine you have a special switch (called a relay) in a circuit that helps control a big switch (called a circuit breaker) that turns electrical power on and off. This special switch is like a gatekeeper.
In the beginning, the special switch is set up so that it only allows the big switch to close (turn on) when it gets a specific command.
There are two parts of the special switch (S1 and A2) that can either be opened (like a door) or closed as you can see below diagram:
When the big switch is told to close, the special switch opens one of its parts (S1) and lets the big switch close.
After the big switch closes, the special switch changes the position of its other part (A2) so that it stops the command from continuously telling the big switch to close.
If, for some reason, the big switch is turned off (tripped), the special switch is set up to make sure it doesn’t accidentally allow the big switch to close again.
Even though the first part of the special switch (S1) might try to open, the other part (A2) is still doing its job to prevent more closing until things are sorted out.
In simpler terms, it’s like having a helper switch that makes sure the main switch only turns on when it’s supposed to, and doesn’t keep trying to turn on if there’s a problem.
Conclusion:
Anti-pumping relay is used to ensure that the close command only goes once to the circuit breaker and after that, no close command can go to the circuit breaker. We have discussed its control circuit with the circuit breaker. If this relay does not work or exists, then the circuit breaker can face severe disadvantages because of pumping (tripping and closing again and again). So an anti-pimping relay helps save that state precisely in large ratings.
