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Thread: Air Compressor "thermal overload protection" issue

  1. #16
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    Quote Originally Posted by Frank Pratt View Post
    If I'm understanding correctly, you are suggesting Scott use the compressor without OL protection? If so, I'm going to strongly disagree with this.

    If it is a machine that is always attended while in operation, then only the motor is at risk. But it's still a bad idea. An air compressor though, can be running when nobody is around and if things go wrong & the motor sets whole place on fire. There was a thread on one of the woodworking forums in the last couple of years where just that happened.

    The argument that a compressor should always be shut off when not being used is no good, because there is a good chance that is not always going to happen. Then in the middle of the night a leak develops & the compressor is running continuously...
    Frank

    No, I am not suggesting that knowingly using a defective piece of equipment is correct. I should have been clearer.
    If this air compressor is manufactured for sale in the US market, with a UL designation, it will have some type of thermal overload protection, or the manufacturers literature will provide the guidance to install it. I believe that there is some form of overload protection built into the motor. It may not be a resettable red button, but an internal fusible link. Without knowing the equipment info, it's difficult to determine.
    I have 7 motors that are always plugged in and always have power to their respective machines .Only two have resettable external plungers. My 5HP air compressor has an external plunger, but it is only plugged in when in use. It is always left pressurized though.I also have a 5HP commercial washer that does not have a resettable plunger, but has an internal thermal switch. The motor connection plate needs to be removed to reset the thermal.
    Some motors have an internal switch that'll reset itself, if it can. Some motors have a fusible link, that will need to be replaced if it pops. Motor protection isn't always in the form of an external red push button.
    Last edited by Mike Cutler; 02-16-2019 at 2:39 PM.
    "The first thing you need to know, will likely be the last thing you learn." (Unknown)

  2. #17
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    Quote Originally Posted by Jerome Stanek View Post
    I have a relay that is controlled by my light switch when I leave the shop I shut off the lights and the compressor shuts down also. I also have a solenoid that shuts the air off

    Your setup is something that I need to do because I don't always remember to shut off the compressor.
    Last edited by Frank Pratt; 02-16-2019 at 5:01 PM.

  3. #18
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    Quote Originally Posted by Mike Cutler View Post
    Frank

    No, I am not suggesting that knowingly using a defective piece of equipment is correct. I should have been clearer.
    If this air compressor is manufactured for sale in the US market, with a UL designation, it will have some type of thermal overload protection, or the manufacturers literature will provide the guidance to install it. I believe that there is some form of overload protection built into the motor. It may not be a resettable red button, but an internal fusible link. Without knowing the equipment info, it's difficult to determine.
    I have 7 motors that are always plugged in and always have power to their respective machines .Only two have resettable external plungers. My 5HP air compressor has an external plunger, but it is only plugged in when in use. It is always left pressurized though.I also have a 5HP commercial washer that does not have a resettable plunger, but has an internal thermal switch. The motor connection plate needs to be removed to reset the thermal.
    Some motors have an internal switch that'll reset itself, if it can. Some motors have a fusible link, that will need to be replaced if it pops. Motor protection isn't always in the form of an external red push button.
    Oh, now I understand. I just didn't want to have anyone to get themselves in trouble by doing something dangerous. You are right that OL protection is not always visible. I would be very surprised if the motor doesn't have some kind of OL protection. Virtually all single phase motors do.

  4. #19
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    Do not worry

    Quote Originally Posted by Scott Driemel View Post
    I purchased a nice 5hp 60 gal "fatboy" style air compressor for my workshop a few years ago. Finally getting around to getting it hooked up.

    Upon closer inspection, I didn't see any "red" reset button on the motor itself which would indicate a "thermal overload" circuit. I'm worried that this motor does not therefore have it. I went to my local large tool store which sells many compressors. They said if there is no "red button on the motor" it probably doesn't have one. They further said with compressors this is pretty important.
    They suggested I buy an "accessory overload switch and have my electrician wire that in". I asked how much and they said about $250.00 for the switch!
    I looked on Amazon and I can buy a 5hp Leeson compressor motor with the overload protection button circuit for about $330.00 (yes I'm up here in the frozen North.) I went back to the store I originally bought it from and see all the newer models do in fact have the obvious red overload button.

    Wondering if it is certain that without a reset button it is certain the existing motor on the compressor is in fact without the circuit?

    Is it critical to have a "thermal overload" capability?

    Is this "thermal overload switch" really this expensive? (I've tried to google it but haven't really found what it is they are referring to)

    and lastly, am I doomed and should just drop the $330 and buy a new motor? (which of course I really don't want to do!)

    I'm not savvy to electrical issues, but have access to a pal who is reasonably handy. I'm a pensioner so money isn't exactly growing on trees (which right now are covered in snow anyways!)

    Any help / advice so very appreciated.
    Of course I don't know your actual application but 5HP/60 gal is a pretty decet specification for an air compressor and after "a few years" it doesn't present problems, I cannot see any reason to looking for inexistent problems. As previously stated, the fact you did not find the "red reset bottom" doesn't meaning your compressor doesn't have some king of overload protection. I would not worry about that.
    All the best.

    Osvaldo.

  5. #20
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    Quote Originally Posted by Osvaldo Cristo View Post
    Of course I don't know your actual application but 5HP/60 gal is a pretty decet specification for an air compressor and after "a few years" it doesn't present problems, I cannot see any reason to looking for inexistent problems. As previously stated, the fact you did not find the "red reset bottom" doesn't meaning your compressor doesn't have some king of overload protection. I would not worry about that.
    Ignorance is NOT bliss. Sure it's probably got OL protection, but that doesn't mean OP should 'not worry about that'. Confirm that it does have protection, then don't worry about it. As I said above, a compressor is the one machine in the shop that might be run unattended. Fires can and do happen when things go bad with that motor & you want to have that protection in place.

  6. #21
    I'm here in Canada, (Vancouver area). I saw on the motor plate it was a "Marathon" made in Wisconsin motor. I thought great! a USA motor not an overseas. I contacted the manufacturer and they identified by model # it as one of theirs. I asked them if it (by not having a "TOPS" button) if possibly the motor had an internal thermal overload. They asked me what the application was on. When I said it was on a compressor I got a big silence. Then I was told there is NO internal safety and that they (the motor manufacturer) would not be liable for fires etc and that they have no control over how 3rd parties might utilize their motors. I got the distinct impression that they did not think this motor was suitable for the application.
    I contacted my retailer with this info and they immediately agreed to have me return the entire unit in exchange for a new one that in fact now has the "TOPS" system.
    My only thoughts are that initially whomever makes these compressors for this Co, used an inappropriate motor which could present a safety issue. I was "on my own" until I contacted the motor manufacturer.
    The bummer is the new models now use some off shore Chinese made 5hp motor not the (albeit) inappropriate USA built one.
    This Co, (similar Canadian version of your Tractor Supply) also carries a few Ingersoll Rand models. Looking at them and talking to an IR rep the motors are Chinese and the pumps probably made in India although the IR's are "assembled" in the USA.
    My store offered me to exchange it for the same (but with TOPS), or an upgrade to the IR model #TS4N5.
    Seems unless you really step up and pay for quality, it is a crapshoot on these offshore models even if from a quality (IR) manufacturer.
    If anyone has personal experience with an IR model TS4N5 (5hp 80 gallon 2 stage) I'd love to hear.
    All your thoughts have been appreciated. I'm hoping to buy one and be done but longevity issues seem to be common on these larger compressors. My little ones are decades old and work like a charm. I'm thrilled my Co I purchased from has agreed for an exchange. I couldn't be happier. Now .. which one?

  7. #22
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    Karl: The second option. Not the first.

    Quote Originally Posted by Karl Loeblein View Post
    Scott, Look at your compressor's motor to determine FLA (Full Load Amps). Then ask your pal if you can install an inexpensive compressor overload protector switch like one of these:

    https://www.amazon.com/uxcell-Circui.../dp/B01N7WG7Y7

    https://www.amazon.com/BIN-BON-Compr.../dp/B07G73TBRH

  8. #23
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    Quote Originally Posted by Brice Rogers View Post
    This thread brings up some interesting issues. When a motor's intended service could include a locked rotor, it would need a thermal protection. An example: a sump or garbage pump that might pull in some debris. But, for an air compressor, that may or may not be needed. I know that I have some motors that are thermally protected (because they have the red button) and suspect that others w/o the button may have the thermal protector built into the motor. But I have never thought of the safety aspect. My air compressor is "live" when I'm home but I always shut it off if I'm on vacation.

    When a motor is in a locked rotor condition it is drawing extra current. So, if the breaker amperage rating isn't too high, perhaps that could cause it to trip. On my radial arm saw, if I'm doing some heavy ripping sometimes I trip the thermal protector and sometimes I trip the breaker - - it is kind of a "jump ball" which one pops first.
    When a motor is in "locked rotor" condition the current is essentially unlimited; or limited only by the electrical resistance of the motor feeder and the windings. A locked rotor that is fairly close to it's source of supply will almost certainly take out the circuit protection breaker. Thermal overloads on the other hand do what the name implies. They protect a hard working motor from damaging itself by working too hard, getting too hot, and melting the internals. Commercial 3 phase motors have no thermal overload protection built in. We install what's called a "starter" that includes "heaters" sized for the horsepower of the motor. They are not designed to protect from over current or short circuit conditions. A "Starter" has a reset button on the front. There are manual switches, made for single phase motors that have provision for installing a "heater" inside to protect for over work. Karl showed one available from Amazon. Others are around from many sources.

  9. #24
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    This is the way we do it in the field. Lifetime electrician.

    https://literature.rockwellautomatio...d002_-en-p.pdf

  10. #25
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    Hi Scott, did your original compressor have a Canadian Electrical Approval?

    CSA, CUL, ULC etc.

    This is not the approval on the motor, this would be a nameplate for the compressor with a CSA, CUL, ULC approval on it, or a third party field inspection sticker.........Regards, Rod.

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