Page 1 of 2 12 LastLast
Results 1 to 10 of 11

Thread: latch/unlatch for an old Asco 925

  1. #1
    Join Date
    Mar 2004
    Location
    West Wisconsin
    Posts
    109

    latch/unlatch for an old Asco 925

    So I have two separate signals (125VAC) that go into each building on campus - one signal fires a "latch" control relay which closes my Asco 925 lighting contactor - (turning on all my ext. building lights) The next part of the sequence - in the AM, fires the other signal and fires the "unlatch" relay which opens the lighting contactor. (which is mechanically held - fired to open and fired to close)

    I want to keep the Asco but would like to replace the two little open style relays labeled - latch/unlatch which fire this.

    What can I use that's only one device - I need a relay which will accept two separate inputs to drive two separate output - all independent of one another. Is this possible??

    I thought years ago I used a "Finder" brand relay that did something like this but am unable to what I'm looking for right now...???

    Any suggestions guys??

  2. #2
    Join Date
    Jun 2003
    Posts
    6,801
    Why insist on using a single relay?

    You might try looking here at Square D Zelio relays and JCK timing relays:

    http://download.schneider-electric.c...9050CT9601.pdf

    https://www.schneider-electric.us/en...d-measurement/

  3. #3
    Join Date
    Apr 2008
    Location
    Ann Arbor, Michigan
    Posts
    6,516
    171222-1400 EST

    sundowner:

    I have no idea what an ASCO 925 is or was.

    An Internet search turned up an ASCO 920, see
    https://www.vertivco.com/globalasset...7_134235_1.pdf

    I still really don't know what this is. Likely it is a motor driven switch with internal logic to allow sustained set and reset signals. Probably requires a substantial amount of current for control and thus is not directly suited for long distance control. That is the reason for the small relay controls.

    A single relay can be used because the the 920 (possibly 925) can tolerate sustained input control signals.

    What is the real problem you want to solve.

    See p5 of the above website for control wiring. Very poor literature relative to the control aspect.

    .

  4. #4
    Join Date
    Jan 2009
    Location
    Port Washington, WI, USA, Earth, Etc.
    Posts
    84
    If you wanted to utilize only one maintained signal, I would think that a SPDT relay would do the trick. Normally open for one condition, normally closed for the other. Unless your signal is momentary, then you could use an alternating relay. I have gone to programmable relays. A few I/O is not much more than a decent relay, and you have so much latitude on what you can do. A GE lighting relay may work too.
    You may well be the sharpest tool in the box, but in the end you are still a tool.

  5. #5
    Join Date
    Jul 2003
    Location
    New Jersey
    Posts
    24,155
    Quote Originally Posted by sundowner View Post
    So I have two separate signals (125VAC) that go into each building on campus - one signal fires a "latch" control relay which closes my Asco 925 lighting contactor - (turning on all my ext. building lights) The next part of the sequence - in the AM, fires the other signal and fires the "unlatch" relay which opens the lighting contactor. (which is mechanically held - fired to open and fired to close)
    Are these two separate signals from the same source on the same circuit? Since you have two existing relays it sounds like they are not.
    Rob

    Moderator

    All responses based on the 2014 NEC unless otherwise noted

  6. #6
    Join Date
    Jan 2016
    Location
    PA
    Posts
    4,500
    Quote Originally Posted by sundowner View Post
    So I have two separate signals (125VAC) that go into each building on campus - one signal fires a "latch" control relay which closes my Asco 925 lighting contactor - (turning on all my ext. building lights) The next part of the sequence - in the AM, fires the other signal and fires the "unlatch" relay which opens the lighting contactor. (which is mechanically held - fired to open and fired to close)

    I want to keep the Asco but would like to replace the two little open style relays labeled - latch/unlatch which fire this.

    What can I use that's only one device - I need a relay which will accept two separate inputs to drive two separate output - all independent of one another. Is this possible??

    I thought years ago I used a "Finder" brand relay that did something like this but am unable to what I'm looking for right now...???

    Any suggestions guys??
    a common latching relay http://www.mouser.com/ds/2/357/105A_755-7090.pdf
    using a form c contact
    potter brumfield
    magnecraft
    etc

    is the 125 latch/unlatch signal maintained or momentary?



  7. #7
    Join Date
    Mar 2004
    Location
    West Wisconsin
    Posts
    109
    Thanks guys...

    gar - my 925 is a 1950's version of a modern Asco920 3 pole lighting contactor.

    I'd like to clean up this install - it is the exact same in several buildings on campus - they all look like hell and now that I have to maintain these I'd like to make things much neater and a lot more straight forward.

    The current set-up is simple - I'm using a remote 120VAC pulse from a central building to pull up my local control relay to fire my lighting contactor - with local control power. Then I fire another pulse to pull up another control relay to open my lighting contactor - it sounds like it should be straight forward and it is - except for the "latch", "unlatch" relays in the circuit.

    My "building automation techs" seem to have horned in on this kind of stuff and if I can control exterior lights with a separate piece of electronics - they would be out of the equation.

    I also remember doing something like this several years ago - just cant seem to remember the relay I used... I like the IEC stuff because it's nice and small - also like the Square D stuff - very reliable.

    Thanks guys!!

  8. #8
    Join Date
    Dec 2015
    Location
    Port Angeles, WA
    Posts
    80
    Quote Originally Posted by sundowner View Post
    Thanks guys...

    gar - my 925 is a 1950's version of a modern Asco920 3 pole lighting contactor.

    I'd like to clean up this install - it is the exact same in several buildings on campus - they all look like hell and now that I have to maintain these I'd like to make things much neater and a lot more straight forward.

    The current set-up is simple - I'm using a remote 120VAC pulse from a central building to pull up my local control relay to fire my lighting contactor - with local control power. Then I fire another pulse to pull up another control relay to open my lighting contactor - it sounds like it should be straight forward and it is - except for the "latch", "unlatch" relays in the circuit.

    My "building automation techs" seem to have horned in on this kind of stuff and if I can control exterior lights with a separate piece of electronics - they would be out of the equation.

    I also remember doing something like this several years ago - just cant seem to remember the relay I used... I like the IEC stuff because it's nice and small - also like the Square D stuff - very reliable.

    Thanks guys!!
    Not sure on how much space you have, but a couple small 'ice cube' relays and a lighting contactor would accomplish your goal easily

  9. #9
    Join Date
    Jul 2006
    Location
    San Francisco Bay Area, CA, USA
    Posts
    7,149
    Pretty much any of the IEC control relay mfrs sell a "latching" accessory for their relays that is an unlatching coil. So you use the regular coil as the "latch" input, and this accessory has another coil that you pulse to "unlatch".

    Here's the one from Schneider / Telemecanique Tesis D line IEC control relays:
    Name:  F4002016-01.jpg
Views: 91
Size:  15.6 KB

    it's important to note that on these devices, regardless of brand, the unlatch coils are never rated for continuous duty. So you either control them with momentary switches, or use a NO contact of the relay to feed the Unlatch coil so that once it operates, it cuts off the coil circuit. You then just need to ensure that when it's time to latch it again, the Unlatch signal is no longer there.
    __________________________________________________ ____________________________
    Many people are shocked when they discover I am not a good electrician...

  10. #10
    Join Date
    Apr 2008
    Location
    Ann Arbor, Michigan
    Posts
    6,516
    171228-2351 EST

    sundowner:

    The 920 can tolerate sustained latch or unlatch signals. It is not necessary to use pulsed control signals. The 920 automatically turns a sustained input input signal into a pulse of a maximum duration it controls. Thus, it does not require a sustained control signal which would waste power. And/or it allows a way to get high mechanical force internally without high sustained external power. And/or it does not require you to supply a controlled pulse signal to prevent burnout of an internal component.

    If the old 925 works the same way, then a SPDT contact in a remote switch can control the 925. This may require large wires if the distance is great. If that is the case, then a single small relay with a SPDT contact can be used as a pilot control. ASCO makes small boards for that purpose as shown in the literature.

    .

Posting Permissions

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