Page 1 of 2 12 LastLast
Results 1 to 10 of 19

Thread: Shunt-trip breaker - help with connections

  1. #1
    Join Date
    May 2005
    Location
    Richmond, Virginia
    Posts
    21,838

    Shunt-trip breaker - help with connections

    I was asked to troubleshoot a supposedly non-functioning electrical cut-off situation in a restaurant fire-suppression system. I traced the wiring to an ITE load-center panel, where a 200a or 225a breaker feeds a panel in an adjoining section.

    There are three black wires and one white wire emerging from the back of the breaker. Two of the black wires are taped off, and the third black and the white wires land on a 2-section barrier strip. I measure 120v between the black and white wires.

    The complaint is from the fire marshal, that the electrical equipment does not de-energize when the system is tripped. The white is grounded, while the black is hot, returning from the fire suppression system. Here is my question:

    Do all shunt-trip breakers trip when 120v is fed into the breaker, or do some trip when the 120v is removed? When I disconnected the wire returning from the system control box, nothing happens. Why are there four wires out of the breaker?

    As always, any info is welcome. :smile: Danke!
    Code references based on 2005 NEC
    Larry B. Fine
    Master Electrician
    Electrical Contractor
    Richmond, VA

  2. #2
    Join Date
    Jul 2003
    Location
    New Jersey
    Posts
    18,905
    Larry, do you have a breaker type? i.e.- QO etc.
    Rob

    Chief Moderator

    All responses based on the 2011 NEC unless otherwise noted

  3. #3
    Join Date
    May 2005
    Location
    Richmond, Virginia
    Posts
    21,838
    Quote Originally Posted by infinity
    Larry, do you have a breaker type? i.e.- QO etc.
    I believe it's an ITE-Gould.
    Code references based on 2005 NEC
    Larry B. Fine
    Master Electrician
    Electrical Contractor
    Richmond, VA

  4. #4
    Join Date
    Feb 2003
    Location
    Massachusetts
    Posts
    48,198
    Larry can you remove the breaker and open it up?

    A lot of larger breakers can be opened up and closed back up with out effecting the calibration.

    If you can get the lid off I bet you could figure out what you have for connections.

    I have never seen a 4 wire set up, usually two black wires, one goes to neutral and the other is powered to trip the breaker.

    Good luck.

  5. #5
    Join Date
    Jan 2007
    Location
    Columbus, Oh
    Posts
    460
    Shunt trip breakers usually require 5ma to 45ma and 120volts to trip (usually).
    It could be that the shunt trip signal is not enough to trip the shunt trip within the breaker.
    You may need to contact the breaker manufacturer, their technical services group can give you this information.
    And then frind out what the output in "ma" the shut trip signal actually is.
    Just my $.02
    I found my easter eggs & my car keys, life is good!

  6. #6
    Join Date
    Nov 2004
    Posts
    1,525
    Larry -

    All the shunt trip CBs I've seen take power to trip. I'd guess the other two black wires are an aux contact, either "trip" or "open".

    Best I could suggest would be to get the cat number and call the mfg.

    Now for the guessing part: Bad news. The trip coil is burned out or the disconnector contact is stuck open. If the trip coil is burned out, it is from the disconnector contacts stuck shut.

    Reasoning: Most of the shunt trips I've seen have the trip coil in series with a disconnector contact that opens when the CB opens. This keeps a continuously applied trip signal from burning up the trip coil.

    This is interesting. Let us know what you find. It will add another point to the troubleshootong database.

    carl
    Using the code for a design guide is a sign of incompetance

  7. #7
    Join Date
    Mar 2006
    Location
    Westchester County, New York
    Posts
    8,169
    Quote Originally Posted by coulter
    Larry -

    This is interesting. Let us know what you find. It will add another point to the troubleshootong database.

    carl

    One of the best aspects of this site.
    Instructor, Industry Advocate

  8. #8
    Join Date
    May 2003
    Location
    Leesburg, VA
    Posts
    6,931
    Larry many shunt trips will have a range of trip voltage 120-240 VAC. A shunt is nothing but a coil, energize the coil the lever moves to trip the CB.

    This could also be undervoltage release, energized all the time, take power way and it trips.

    If this is a factory install device it is most likely listed on the CB, shunt trip or UV release, with operating voltage.

    If you have a variac you can ramp up the voltage and see if it trips, though the Shunt trip voltage can be 24 VDC, 120 VDC, 24 VAC, 120 VAC 240 VAC 0r 120-240 VAC.

    Lastly it may be a multi voltage relay with taps (unlikely in my expierence) or the additionally conductors could be coil clearing leads, contacts that open to take power off the coil. Some shunts are designed to be energized for a short period of time. Energize tthe device to trip and the clearing contacts remove power from coil after the CB opens.


    So you have a variety of options.
    Brian John
    Leesburg, VA

  9. #9
    Join Date
    Aug 2005
    Location
    Dayton Ohio
    Posts
    155
    Quote Originally Posted by coulter
    Larry -

    Most of the shunt trips I've seen have the trip coil in series with a disconnector contact that opens when the CB opens. This keeps a continuously applied trip signal from burning up the trip coil.



    carl
    At least one manufacturer (I don't recall) has a trip coil seperate from the breaker which you install in the field. If you don't align it properly it will supply voltage continuously.
    I started out with nothing and still have most of it left.......

  10. #10
    Join Date
    Jun 2004
    Location
    San Francisco, CA
    Posts
    5,465
    I have seen these things a few ways, most common would be 'powered' (Shunt) to trip, and it's buddy, 'no power' (Under-voltage) to trip. (At various voltages) I have not seen one with both, but for a breaker that size anything is possible. (I often see the Shunt module that goes into the space next to the shunted breaker - they have a tab that sticks into the breaker - but it doesnt sound like you have one of those.)

    ITE is Seimens - I think.... And they may be simular any way... Look at around page 30 here... I'm only assuming its a J or F -frame?
    Electric heretic
    It's always gonna be in the last place you look....

Posting Permissions

  • You may not post new threads
  • You may not post replies
  • You may not post attachments
  • You may not edit your posts
  •