I need electrical help...please

Discussion in 'Homesteading Questions' started by 65284, Apr 11, 2005.

  1. 65284

    65284 Well-Known Member Supporter

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    I have a problem I can't solve on my own. I have tried to hire several persons but it isn't a lucrative enough job and no one is interested.

    Problem, I have an older incubator with the wafer and snap switch type controls and the snap switch went bad.

    I wanted to upgrade from this type of controls anyway so I bought controls from the Petersime Incubator Company. I hope this description is understandable to someone.


    These consist of a box with a face plate made of some sort of composite material. The plate has 2 clips, similar to the old automobile type fuse block clips. There is a glass "thermometer" a tube that contains mercury and has 2 metal bands around it and a wire that go through the tube and these bands, the bands snap into the clips. When the temp rises to the proper level the mercury expands and contacts the wire and shuts off the heating element.

    There are also 3 terminals on the front side of this face plate, Red, White, and Black that extend through to the back side. There is a brass bar from the white terminal to one of the clips. It came with a moveable jumper wire attached between the black and white terminals. I have no idea if this is relevant or not.

    Screwed onto the back side if the faceplate is a block that says "Douglas Randall solid state relay, model a25a nc". There are 4 screw down terminals (at least that's what I think they are called) numbered 1,2,3,4, there is a line drawn between 1 & 2 with what appears to be a switch symbol in it, on the left side of the "switch" it says 120 vac on the right side of the "switch" it says 25 amperes. There is a line between 3 & 4 with a circle in the center, on the left side it says 90-260, on the right side it says vac. There is a red wire from the bottom of the plate (the red terminal) to # 1 on the relay. There is a black wire from the black terminal to #2 on the relay. There is a yellow wire from the clip where the metal band on the thermometer snaps in to #3 on the relay. There is a brass bar between relay terminals 1 & 4.

    On the old controls there were 2 wires 1 white and 1 black. The new seems to need 3 wires. How do I proceed from here?

    Any help will be appreciated.
     
  2. agmantoo

    agmantoo agmantoo Supporter

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    A stab in the dark. The mercury portion of the new thermostat controls the temperature but is not able to handle the amperage of the heater. The solid state relay is used to handle the amperage and is where the heater connectors go (the wires you took from the old wafer device) The jumper wire is probably to protect the circuit during transit. If you could post a few pics it would be extremely helpful.
     

  3. 65284

    65284 Well-Known Member Supporter

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    Can't do pictures my old camera isn't compatible with new computer. What is the third terminal for, should there be a third wire from somewhere? What is the likelyhood of this thing working if I connected the black heater wire the the black terminal and the white wire to the the white terminal an the controls?
     
  4. farminghandyman

    farminghandyman Well-Known Member Supporter

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    if you do it wrong it will probly fry it. web site or some thing may help. call the company for a direction sheet,
     
  5. agmantoo

    agmantoo agmantoo Supporter

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    Another grop in the dark. I am guessing that the thermostat is able to control a cut in or a cut out on temperature rise, thus the 3rd wire!
     
  6. farminghandyman

    farminghandyman Well-Known Member Supporter

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    I have been looking up possible hook ups on different company relays and I think you going to have to have the company send you a drawing of the proper hook up, and it is possible you may need a transformer to operate the Mercury thermostat,

    Is it a single pole relay or a double pole?

    It is possible it is not even the proper unit for your upgrade,

    with out more information I can't even give you a guess,

    it is possible it is similar to this on page 2 of the manual

    http://oeiwcsnts1.omron.com/pdfcatal.nsf/PDFLookUpByUniqueID/3A758ACD1AEEF94C86256B880074CC5A/$FILE/D20G3PA0302.pdf
    or on page 7 and 8
    http://oeiwcsnts1.omron.com/pdfcatal.nsf/0/E03B55A4B7916E3C86256FC8005DC3C8/$file/D20G3NA0305.pdf

    I cant find the company web site you said made the unit or the model listed in supplier,("Douglas Randall solid state relay, model a25a nc".)

    my guess is the three wires on the thermostat are so it could be used for heating or cooling,
    one is common and they you use one of the other for either heating or to cool, (like in home thermostat that works the furnace and the AC). in the home thermostat you have switch in your case you probably just choose two of the wires,

    here is a hand book on solid state relays
    http://oeiwcsnts1.omron.com/pdfcatal.nsf/PDFLookupByUniqueID/C370DE71E014ACC286256AAF00477A5F/$File/C20Y108E11.pdf?OpenElement
     
  7. farminghandyman

    farminghandyman Well-Known Member Supporter

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    it looks like it did not do the URL's right so you will have to copy and past them in to the adress bar on your computer,
     
  8. mikell

    mikell Well-Known Member

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    Let me get my first cup of coffee down. I went to the website and didn't see a parts area. On your SSR (Solid State Relay) the top is for heater control and the bottom comes from the thermostat. On the theromometer probably the center would be common(White) the ends would turn on for heat the other would be for cooling(I think). The jumper may be to use the end and center for common. But really you should contact the company and let US know how close we were.


    mikell