52A & B As Applied To Medium Voltage Reclosers

Thread Starter


Joined Jun 20, 2009
I am reading some materials about reclosers, specifically, Cooper/Eaton Form 6 recloser. One thing I have been unable to determine is what a 52 a or b contact is. I looked up "52a Recloser" on Google and found that this applies to multiple manufacturers of reclosers.

Does anyone know what this term means?

Here is a quote from Cooper's manual:

"There are several conditions that will cause the alternate
and RECLOSER CLOSED LEDs: Failure to Trip, Failure to
Close, Interrupter Malfunction, and 52a/b Disagreement."


Joined May 23, 2014
From wikipedia:

Latching state devices[edit]

Where the state of the operating device can be latched in either state and therefore the normal state is not clearly defined a different style of contact definitions may be used.

Form A contact[edit]
A Form A contact is closed when the operating device main contact or mechanism is closed or latched. Its function is logically equal to the device it resides on.

Form B contact[edit]
A Form B contact is a contact that is closed when the operating device main contacts or mechanism is open or latched open. Its function is logically inverted to the device it resides on.

I don't know if this necessarily applies here, but that is my two cents.


Joined Nov 21, 2006
b1u has got it right. The "a" contact is closed when the breaker (or recloser in your case) main contacts are closed.
The "b" contact is opposite of this.
IEEE device function number 52 is a circuit breaker, and more accurately stated it is an AC circuit breaker.

It is common in larger, medium and high voltage electrical devices such as breakers to have multiple auxiliary switches (52a and 52b)
that operate along with the main mechanical linkages of the device. These are typically used in control and protective
schemes, as well as for reporting status of the device. Where I work, it is standard to use a 52a contact to report
the open/close state of a circuit breaker to the control center.


Joined Dec 13, 2013
around here, reclosers are used on power lines to trip under overcurrent, then reclose after a time set internally. the a and b refer to no and nc contacts in the recloser.


Joined May 23, 2014
Thank you for elaborating, subtech and alfacliff. We use Form A, B, and C (NO & NC) switches in our actuators, but our ratings do not exceed 250VAC. I wasn't sure if the logic carried over to medium and high voltage, but I am happy that it does. It seems so rare in industry that this occurs.