What is Circuit Breaker making current release?

[dfdt]

Can some one throw some light on what is " making current release" in context of circuit breakers.

As per standard AS 62271-100-2008 it is defined as

"Release which permits a CB to open, without any intentional time delay,during a closing operation ,if the making current exceeds a predetermined value, and which is rendered inoperative when the CB is in closed position"

 

[waross]

In a closed position some breakers may carry a current greater than they may safely close into. Many breakers incorporate a "Trip free" feature (A code requirement for some classes of breakers). Trip free is often achieved by collapsing a toggle link in the closing mechanism. On larger breakers it may be accomplished by relay logic and lock-out relays. When the trip free has been operated the breaker will not close until the trip free has been reset.
On a large breaker the instantaneous trip current when closing may be a different setting than the instantaneous trip current when the breaker is closed.

Bill
--------------------
"Why not the best?"
Jimmy Carter

 

[dfdt]

Are referring anti pumping feature?

 

[Zogzog]

Yes, anti pump, usually controlled by a "Y" relay.

 

[sibeen]

It is just a feature in a breaker which doesn't allow it to close onto a fault. Any time delay functions that are set on the instantaneous setting are disabled when the breaker is attempting to close.

 

[dfdt]

As we know that electrically circut breaker is closed or opened by energising close coil or trip coil respectively either locally of remotely. I also understand function of anti pumping relay in a CB. I am struggling to understand Waross statement that "Trip free is often achieved by collapsing a toggle link in the closing mechanism"making current release"

 

[waross]

Canadian Electrical code:
"Circuit breakers
14-300 Circuit breakers, general
(1) Circuit breakers shall be of the trip-free type."

This applies to manually operated circuit breakers.
There is often a toggle in the operating mechanism of the breaker. The trips collapse this toggle allowing the breaker to open by spring action, sometimes aided by the magnetic force of the current.
Even if the breaker handle is held in the closed position, when the toggle collapses the breaker opens. Resetting the breaker resets the toggle into the normal operating position.
Sorry.
I didn't realize you were speaking about electrically operated breakers.

Bill
--------------------
"Why not the best?"
Jimmy Carter

 

[dfdt]

WAROSS - thanks for the explanation

 

[wroggent]

On a Digitrip 520, would a blinking instantaneous LED indicate that a breaker tripped as a result of the MCR function? I just looked at a breaker with the instantaneous LED blinking but the breaker is not tripped. I'm not sure what that means. Does anyone know?

Manual:

http://www.eaton.com/ecm/groups/public/@pub/@electrical/documents/content/70c1037.pdf

See page 17 for details on MCR.

 

[Zogzog]

Either the breaker tripped and someone forgot to reset the LED or your trip unit battery is "mostly dead". Hit the target reset, if it is still blinking replace the battery.