Help with Relay tester

Discussion in 'Homework Help' started by Renemiami, Nov 21, 2014.

  1. Renemiami

    Thread Starter New Member

    Nov 21, 2014
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    Hello guys, I am an elevator mechanic, with some knowledge in electrics.
    Long story.....will try to make it short.
    Older elevator controllers have hundreds of relays that go bad and cause trouble. As a mechanic, you can isolate the problem to 10, 20 relays...then you have to test/replace the relays until the elevator functions properly and the process is very time consuming, so I decided to venture and make my own relay tester.
    First attempt was successful. Installed components in a box....
    Relay socket....
    push on and off switch
    six led's since there are usually 3no contacts and 3nc contacts in the relays.
    Connect the unit to 110vac, insert relay in socket(coil of the relay is 110vac), three led's are lit. Push the switch, coil is energized the nc led's are off and the no led's are on.
    IF there are any bad contacts...one or more led's will not lit.

    So far so good. But we have relays with coils reated 110vac, 220vac, as well as 12,24,48,120vdc relays.
    Tried to improve the little box. Bought a couple of parts....started to draw the circuit..it did not come up so well.

    What I have...
    6 110vac mini lamps (relays have 6 contacts)
    relay socket
    two dpdt switches
    one push/release switch
    one standard potentiometer
    one 120 to 240 vdc (step up)converter
    one diode rectifier
    one fuse holder

    Could somebody do the drawing for me so I could make this happen.....and be able to get some sleep as well..lol.
    thank you in advance.
     
  2. MikeML

    AAC Fanatic!

    Oct 2, 2009
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    Separate the coil side from the indicator side.

    On the Load side: Best to use incandescent lamps that draw substantial current through the contacts under test; rather than use LEDs. Voltage your choice...

    On the coil side: Can you use a small Variac for the AC coils, and add a simple full-wave bridge/capacitor DC supply behind the Variac?
     
  3. Renemiami

    Thread Starter New Member

    Nov 21, 2014
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    Yes, I am using incandescent lights...just called them leds. The lamps are being fed separately...110vac. My problem is ..in my drawing, either way I connect it, the current returns to the other circuit....say if I supply 220vac...it returns current to the bridge/capacitor once it reaches the relay coil....
    I have done the drawings many different ways and I am missing something.
     
  4. MikeML

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    Oct 2, 2009
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    If you are using one power supply, then the load side must be common with the coil side. If using two independent supplies, no common connection is required. What is wrong with having a common connection?
     
  5. Renemiami

    Thread Starter New Member

    Nov 21, 2014
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    I want to be able to supply any ONE of three(3) different currents to the coil, depending on the relay being tested. (110vac), (220vac) or (12,24,48,110VDC). If I send 220vac, 220vac is returned to the bridge once the connections meet at the coil poles......I am sorry for my English..I am a Spanish speaker..
     
  6. MikeML

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    For safety, you should use a transformer to power the coil. Do you have a 240Vin to 240V transformer? Does the transformer have any taps?
     
  7. Renemiami

    Thread Starter New Member

    Nov 21, 2014
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    I have a 110vac to 220vac..small...no taps, just three wires.
    110 in 220 out
     
  8. MikeML

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    Is the line voltage in your country (good reason on putting in your location when you register for this web site) 110V or 220V?
     
  9. Renemiami

    Thread Starter New Member

    Nov 21, 2014
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    I am sorry. I am in Florida, 110vac is the line voltage here.
     
  10. MaxHeadRoom

    Expert

    Jul 18, 2013
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    If this used in a residential location, you should have 120vac and 240vac available.
    Max.
     
  11. Renemiami

    Thread Starter New Member

    Nov 21, 2014
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    But a 240vac outlet is not easily found. I would like to include the little transformer to do the job when needed....if possible
     
  12. MikeML

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    Can you also scrounge a small 120V to 12V or 24V AC transformer (AC output Wall-Wart plug in)? Good sources are thrift shops and Habitat for Humanity. Sprinkler timer transformer would do.
     
  13. MaxHeadRoom

    Expert

    Jul 18, 2013
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    If you need a small 120v/240 control transformer they are available from any electrical supplier, just use the 240v/120 connected in reverse.
    Max.
     
  14. Renemiami

    Thread Starter New Member

    Nov 21, 2014
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    Please I need help with this matter. Anyone?
     
  15. MaxHeadRoom

    Expert

    Jul 18, 2013
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    That no mean project, do you have a drawing that you can post and we can critique it?
    I take it that mechanics are your forte, not electrics.
    Just as an aside comment, does it not require a electrically qualified person to do the electrics on an elevator?
    The only one I ever was involved and converted was an old freight elevator, it originally had a hemp rope running up to a reversing contactor, and the rope pulled the contactor over to go either up or down, the floor L.S.'s stopped the motor.:eek:
    Max.
     
  16. djsfantasi

    AAC Fanatic!

    Apr 11, 2010
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    Several good ideas have been presented here. I put together a block diagram of how I see the project.
    I broke it down into modules. Used multiple transformers, one for each desired voltage to be tested. I fed the 110vac through, but for safety, you may want to consider isolation transformers.
    A DP6T switch selects which of the power supplies is sent to the relay socket for the coil. Since break before make is specified, there's no chance of the voltages comingling.
    The indicator lights can be powered from the same feed as the power supplies.
    Here is the diagram. Note that I didn't include all wiring routes, as the diagram would become unreadable. I hope it is readable as it is anyway.
    Untitled.png
     
  17. djsfantasi

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    Apr 11, 2010
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    By the way, I think you can get your 12/24/48 volt supplies with two 12v and one 24 volt transformers.
     
  18. MikeML

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    Nandu, instant smoke. You cannot have the four bridges tied that way. The voltage selector switch would have to be between the transformer taps and a single bridge...

    You could get by with only a single 120V to 240V w/CT tranny. There is no reason why the coil must be totally isolated from the indicator lamps.

    I am afraid that the OP will have great difficulty in finding the transformer with all of the taps.
    I would be inclined to substitute a small Variac, followed by a DC voltmeter to preset the coil voltage prior to testing a relay.

    73
     
    Last edited: Nov 22, 2014
  19. MikeML

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    Actually, a cheaper way of getting a variable DC voltage from 12V to 48V (for the coils at ~100mA max) would be to use a $10 120Vac lamp dimmer followed by a diode bridge and a filter capacitor. I would have to try this to see that the dimmer was stable into such a load. Possibly using the dimmer with a 25W or 50W lamp before going into the bridge would stabilize it...
     
  20. MikeML

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    Put a bleeder resistor across the filter cap.
     
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