I saw that, but isn't that for the voltage passing through the actual contactor itself, not the coil voltage? On the spec sheet of the contactor it says the coil is rated at 120 V...
Yes indeed, the notes on the contactor are for the voltages/currents it can switch.
see if you can find a service manual for your oven then find the the correct original part for you oven. Then if you feel the original part is underrated buy a contactor with a higher rating. I had to do that for my ground source heat pump. The power transformer and contactors were failing to often. I had the unit repaired by factory authorized technicians under waranty. It wasn't till I replaced the 50 watt power transformer with a 100 watt unit and replaced the main 20 amp contactor with a 30 amp unit and upgraded 2 other relays from 15 to 25 amps that I was able to run the unit reliably. I achieved 15 years reliability after I upgraded the parts. The Original parts rarely lasted more than a few months and the service guy always had to come back the next day with a part. I would miss 2 days work and received endless complaints from the wife. Reliabilty is important when it is -25C outside.
Thats the problem, in the manual it just says "all service should be performed by authorized technician" blah blahh
I just picked up a nice ($150!!) Schneider electric Contactor. (240 V coil) I'm going to install it now and test the oven! Fingers crossed!
I just picked up a nice ($150!!) Schneider electric Contactor. (240 V coil) I'm going to install it now and test the oven! Fingers crossed!
Do you know how many amps the heating element draws? Maybe you best parallel all 3 contacts on your contactor to be sure you do not stress them, many electric ovens are 3kW or above, that is over 13 Amps at 230Volt...
Actually starting currents are much higher, but he is burning out the coil. When a relay is sold as a contactor that usually means they are three pole or more and at least 20 amps resistive. Most are designed for motor starting and have high surge capacity.
I have never tried it but I would expect a 120 volt coil to burn out fairly quickly on 240 volts. I would expect a 240 volt coil not to pull in at all or very slowly on 120 volts. That would cause the contacts to burn out faster.
As most modern meters draw almost no current when measuring voltage, dirt can cause leakage current from a higher voltage source that may cause a bad reading. So if the relay burns out again try sending the coil voltage to a 25 watt incandescent light bulb rated at 120 volts. It will tell you in seconds what the loaded voltage really is!
It's less than 3000watts. The 5 turn heating coil is only 3300 watts, mine is only a 3 turn coil.
The oven works perfectly now. Well...the fan motor gets very hot to the touch after 10 minutes of use. It's an exposed magnet, but I don't think it should be getting so hot.
Ohh well, that wasn't the problem that I was supposed to repair. So I'll bring it back working and if the fan motor burns out in the future I'll replace it. (this is actually going to be used as a backup now, they ordered a brand new one already)
The oven works perfectly now. Well...the fan motor gets very hot to the touch after 10 minutes of use. It's an exposed magnet, but I don't think it should be getting so hot.
Ohh well, that wasn't the problem that I was supposed to repair. So I'll bring it back working and if the fan motor burns out in the future I'll replace it. (this is actually going to be used as a backup now, they ordered a brand new one already)
So what is the voltage across the fan motor? Sounds like the AC input connections might be wrong!
(Also I suspect a shorter heating coil will draw more current! But clearly that is not a problem,)
(Also I suspect a shorter heating coil will draw more current! But clearly that is not a problem,)
I didn't check voltage across the fan because it was never broken since day 1. So I doubt anything changed on the input wiring. And for the rest of the oven to work properly I assume the input connection is wired up correctly, no?
Black wire went to the single screw on the bottom, and the two hots went to the upper two screws...that seemed correct to me.
Black wire went to the single screw on the bottom, and the two hots went to the upper two screws...that seemed correct to me.
I know he burned out the coil, but he bought a new contactor, and just to make things sure (melting because of overheating, because of overcurrent) I suggested he parallels the contacts, easy enough and better then just not using em 🙂
If it is the fan for the hot air in the oven it is normal that it gets very hot, the blade actually lets the hot air circulate in the oven and some of the heat is conducted to the motor. You could still do a check, and see if there are any voltages written on the motor and then measure the voltage over it to see if it corresponds...
^I'm going to have to disagree with that being the reason the motor was getting so hot, because yesterday I didn't even have the heating coil powered up (power lines were disconnected from the contactor) and after operating the fan for a few minutes it was hot.
I returned the oven for them to use today, I'll be in there tomorrow and see if there was a problem after using it all day today....
I returned the oven for them to use today, I'll be in there tomorrow and see if there was a problem after using it all day today....
Agreed, but interestingly enough the current rating does not triple! It only goes up by about 70% 🙂
It's pretty obvious that the problem is a 120 volt coil on a 230 volt circuit.
It doesn't seem that the fan or the contacts are the problem.
It doesn't seem that the fan or the contacts are the problem.
Correct. The power to the fan isn't broken by the Contactor. Only the power to the heating element is.
That's why I also wrote that you could do a check to be sure it was that.
@simon7000, I did not know that, why is it only 70% more?
Because they don't exactly close or open at the same time! So for safety reasons it is the square root of the sum of the individual ratings squared.
As I am sure you understand the hold current is the easy part normally, it is the arc at opening or closing that does real damage.
Yes, I never thought about the time it takes to open/close, thank you for learning me something!
It would be indeed "dangerous" to just simply triple the current, I'm imagining now what would happen when one of the three contacts would have a bigger delay or fail...
I'm sure a small arc Is present during opening and closing, but the new Contactor seems strong as hell. When activated, it shakes the entire machine with a tiny thunk! Noise.
As for the motor heating up, i believe the centrifugal switch is the culprit? I saw that a new Dayton starting capicator was recently replaced in there. I'm guessing the guy who did the work never checked the centrifugal switch...and the start winding staying on is what is causing the heating of the motor, And possibly what killed the original cap.
The motor does, however, change direction every two minutes. That wouldn't mean that there is an absence of a centrifugal switch right? Don't all AC motors have a switch?
As for the motor heating up, i believe the centrifugal switch is the culprit? I saw that a new Dayton starting capicator was recently replaced in there. I'm guessing the guy who did the work never checked the centrifugal switch...and the start winding staying on is what is causing the heating of the motor, And possibly what killed the original cap.
The motor does, however, change direction every two minutes. That wouldn't mean that there is an absence of a centrifugal switch right? Don't all AC motors have a switch?
Not all motors are capacitor start, some use a capacitor to run!
The thunk noise is a great sign! It means the contactor is closing quickly. That means you got it dead on, it always should have been a 230 volt coil! Now I am surprised by how long a 120 volt coil lasted.
So what is the voltage rating on the motor capacitor? Is it a smaller motor start type in a small plastic case or a metal cased and larger motor run type?
The thunk noise is a great sign! It means the contactor is closing quickly. That means you got it dead on, it always should have been a 230 volt coil! Now I am surprised by how long a 120 volt coil lasted.
So what is the voltage rating on the motor capacitor? Is it a smaller motor start type in a small plastic case or a metal cased and larger motor run type?
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