Magnet Coil and Closing Coil in Vacuum Contactor?

If I may add, one of the normally open auxiliary switches has to be used to pass a separate 24V power which by doing so will ensure the solenoid coil is continuously powered, to stay latched during any power disturbance in the line.

Thank you! I don't understand why there is a "operating voltage" required for the closing latch if it is purely a mechanical latching operation.

The closing latch hold the main contacts closed, once the magnet coil has moved them into position.

Since the trip springs are also charged with the same motion of closing, the magnet coil has a high energy requirement.

The closing latch is moved into position once the magnet coil has moved the main contacts. The closing latch coil is what moves the latch at the correct time.

Since power distribution breakers are typically operated with a separate and uninterruptible control power source, having separate power to the various components allows the user to tailor the power source to the needs of the system.

In some cases, it may be acceptable to take the closing magnet power from the incoming line, reducing the size of the battery, for example.

In other cases, the ability to close a breaker on a dead power system is needed, when bootstrapping up an islanded power system.

Ask yourself the question. what actuates the mechanical action required for the "closing latch" to function ??

The mechanical action cannot take place until a force is used to operate the action, physical, mechanically, electrically, vacuum, air pressure, etc.

Example: a car door lock has a mechanical "locking latch" but it needs the door to be closed from the open position for it to function, just as it has a separate mechanism which is used to unlatch it (door handle).

Thank you, still couldn't get it completely.

For example, In the case of Vacuum circuit breakers, there is only opening coil and closing coil - this I understand.

In Vacuum Contactor :

Magnet coil: same as closing coil in the vacuum circuit breaker

Closing latch: Equivalent to what in VCB? why this needs electrical power?

Although there is only one coil for the vacuum contactor, it is very possible that a latching control voltage for the same coil is done thru the use of an interlock ckt. Accomplished by applying and using the latching control power via a N.O. auxiliary switch that is connected in series to the single coil part the vacuum relay.

A contactor generally will open upon release of control power. Control power is taken from the mains supply. Interrupting control power will cause the contractor to open. Thus happens when the mains power is interrupted, and is generally desired in the case of main bus power loss.

A circuit breaker will stay closed regardless of the control power availability. A breaker will require control power to trip, and control power to close. In the case of the closing latch, this allows the magnet coil to be deenergized, without the main contacts opening. If you did not have the latch, then loss of control power would allow the contacts to open. This is peculiar to the mechanism design, and can vary widely among manufacturers. This is Siemens design for circuit breakers.

The closing latch hold the main contacts closed, once the magnet coil has moved them into position.

Since the trip springs are also charged with the same motion of closing, the magnet coil has a high energy requirement.

The closing latch is moved into position once the magnet coil has moved the main contacts. The closing latch coil is what moves the latch at the correct time.

Since power distribution breakers are typically operated with a separate and uninterruptible control power source, having separate power to the various components allows the user to tailor the power source to the needs of the system.

In some cases, it may be acceptable to take the closing magnet power from the incoming line, reducing the size of the battery, for example.

In other cases, the ability to close a breaker on a dead power system is needed, when bootstrapping up an islanded power system.