Motorized MCCB - "Trip Position" 2

[NickParker]

I hear that the motorized MCCBs which have UV release or shunt trip do not move to "Trip" position on acting of UV release or shunt trip, It just moves to "Open" Position.
Only on overcurrent faults, it moves to "Trip" position. Is it correct?

 

[LionelHutz]

Any MCCB I've used, the UV or SH actually trips the breaker same as pressing the test button on the front of the case. The motorized operation which mounts on the front and moves the toggle handle wouldn't change this operation.

 

[jraef]

Lionel is correct. The motor operator is not used in the tripping functions.


" We are all here on earth to help others; what on earth the others are here for I don't know." -- W. H. Auden

 

[che12345]

dear Mr. NickParker (Electrical)(OP)13 Oct 22 11:07
"...#1.I hear that the motorized MCCBs which have UV release or shunt trip do not move to "Trip" position on acting of UV release or shunt trip, It just moves to "Open" Position.....#2. Only on overcurrent faults, it moves to "Trip" position. Is it correct?"
#0. A basic breaker shall be marked with symbol I=On, O=Off but Trip without symbol, indicated by the operating handle position.
#1. Different manufacturers may have different motorized unit. One of the common types on the market where the motorized unit is placed on top of the standard MCCB; covering the operating handle and the status indication. The motorized unit has only I=On and O=Off ; but without Trip indication.. Therefore, irrespective of whether the breaker is [opened by UV, Shunt, thermal over-load, short-circuit over-current and Off by the push-button, the motorized unit shows O=Off.
#2. No, The motorized unit indicated O=off. There is NO Tripp indication, see above #1.
#3 BTW: this is one of the types, there may be different designs with different indications on the market.
Che Kuan Yau (Singapore)

 

[che12345]

@ Mr.LionelHutz
@ Mr. jraef
"...Lionel is correct. The motor operator is not used in the tripping functions."
1. I am of the opinion that the above learned advice is irreverent. The question did not ask on whether it is used for the tripping function.
2. It is obvious that the motorize unit is solely used for (opening/closing) of the breaker; [locally by manual push-button on the motorized unit] or [by Remote electrically]. It has NO protection function.
Che Kuan Yau (Singapore)

 

[unclebob]

More over, the manual I have suggest the use of a Bell alarm contact. Then use a lamp or another mean to indicate automatic trip operation.

 

[NickParker]

#2. No, The motorized unit indicated O=off. There is NO Tripp indication, see above #1.

I failed to mention about the auxiliary contact (Schneider NSX series - SDE contact). The SDE contact change over its contacts only for overcurrent protect not for the UV/shunt trip activation.

 

[che12345]

Dear Mr. NickParker (Electrical)(OP)16 Oct 22 17:02
"....I failed to mention about the auxiliary contact (Schneider NSX series - SDE contact). The SDE contact change over its contacts only for overcurrent protect not for the UV/shunt trip activation...."
1. Yes, you are correct..
2. Note: There is a distinct differentiation between "Alarm" and "status" indication.
Very often we say UV or Shunt "trips" open the breaker. It should be "opens" NOT Trip".
3. When a breaker is Opened by the UV or Shunt, the contact changes status as a "status" open/closed indication. It has nothing to do with the "Alarm".
Che Kuan Yau (Singapore)

 

[FreddyNurk]

Schneider, as a specific example, also has the means of automatically resetting the toggle position with a motor operator when configured to do so.

MCCBs can be confusing as the presence of a trip position on the toggle gives rise to 3 possible states rather than two, as opposed to something like an Air Circuit Breaker.
Important definitions (may vary by manufacturer, at least one I know of goes to the trip position from open when tripped via a remote coil or test position):

Open operation (carried out by a motor operator, not suitable for use with protection functions that expect the breaker to open)
Trip operation (either via onboard protection unit or via trip coil and external interface)
Close operation (via motor operator only)

An open operation will effectively put the MCCB toggle in the open position. An open operation is also often used to reset the MCCB remotely when tripped.
A trip operation will generally (I've not come across one that doesn't) put the toggle into the trip position.
A close operation will put the toggle into the closed position.

The distinction arises in terms of what has caused the breaker to go to the trip position, is it a fault detected by an internal protection device, or is it from an external device?
The operation to be undertaken may vary depending on the circumstance, such as a backup UV release being used to ensure the breaker is open when voltage is lost. In that case the breaker can be automatically reset and put into service.
In such a case something like the SDE contact for a Schneider breaker is used as it flags an internal trip but not an external one.



EDMS Australia

 

[Amit Bajpayee]

@FreddyNurk Thank you for such information.

https://agnisolar.com/