trying to substitute obsolete relay for oven

Thread Starter

nickit88

Joined Apr 3, 2017
30
Only somewhat familiar with electronics, so please bear with me.
I have a GE oven with a bad oven relay (dual contacts with one contact burned out)
Part is not available anywhere and my parts guy suggested a 30 amp relay used for an air conditioner. It worked, but apparently the signal coming from the thermostat/oven temp control either sends the signal to the relay multiple times in rapid succession or it is the nature of these to have a fluctuating signal output.

Anyway, the problem is the old relay is basically some windings that when heated slowly closes the contact point (takes about 5-10 seconds to close, makes no sound). The AC relay I am attempting to substitute slams the points shut. As a result, the fluctuation of the signal is causing it to close and open rapidly five or six times when the thermostat turns the signal on or off. It doesn't do it when I set the temperature dial manually, only when it is responding to the oven's temperature sensor and automatically cycling on or off to keep the temperature at the level set on the dial.

The original heated winding type relay has a ceramic disc capacitor across the signal terminal (voltage from thermostat dial) and common (white). Is it's likely purpose to buffer/filter the signal to prevent the switch from fluttering off and on, and if I add the same capacitor to my replacement AC slammer relay will it tame the signal to prevent the rapid opening and closing? I can live with the "click" of the replacement relay, but not the stuttering clicking off and on, which I imagine will shorten the relay's life.
 

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Thread Starter

nickit88

Joined Apr 3, 2017
30
Yes, search for the Coil voltage and contact rating like this...


http://m.ebay.com/itm/331326301626
I know the specs of my replacement relay, which like I said I already bought. It works, it's just that it clicks like crazy when the thermostat cycles on or off.
The old relay had a capacitor on the signal terminal and I'm wondering if I should add one to the replacement, and if so, what size/rating capacitor.
 

Thread Starter

nickit88

Joined Apr 3, 2017
30
Page 2 of schematic. I highlighted the relays in red
Here is a picture of the new relay I am trying to get to work. If I crank on the oven dial it clicks once and heats the oven fine - until it reaches temperature. When the thermostat triggers the relay off, that's when it goes nuts switching off an on rapidly until it finally settles down and the contacts stay open. Same stuttering and rapid opening and closing when the thermostat cycles the oven back on.
 

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Thread Starter

nickit88

Joined Apr 3, 2017
30
The capacitor is across the relay contact terminals, suppression of sparks.[/QUOTE
Makes sense. Is there a way to tame the flickering/flaky signal so my slammer relay doesn't go nuts. Or is there a 30amp relay out there that can handle a signal that fluctuates for a couple of seconds the way my thermostats appear to do?
 

#12

Joined Nov 30, 2010
18,223
Could that be what I need.
A delayed relay is perfect for this job but that article provides no part numbers, so it is useless for actually building or repairing anything.
I've been thinking about this question but I can't name any relay with a 5 second delay.:(
 

Thread Starter

nickit88

Joined Apr 3, 2017
30
A delayed relay is perfect for this job but that article provides no part numbers, so it is useless for actually building or repairing anything.
I've been thinking about this question but I can't name any relay with a 5 second delay.:(
I've found several time delay relays on the net. Many have dials so you can set the time delay you want. Just need one heavy enough to carry 30A at 120v.
As an aside, I just measured signal voltage to the relay with the oven cycing off and on. When the thermostat switches the signal on and off, the voltage changes in increments, up or down in 15 to 20 volt increments over about three seconds until it gets to 120v cycling on or 0v when cycling off, which I assume is what is making my relay go nuts opening and closing rapidly.
 

MaxHeadRoom

Joined Jul 18, 2013
24,206
Too bad you are not familiar with Picmicro's, the app note AN958 could be modified to do this electronically by Triac.
It is for a replacement to a Mechanical thermostat.
Max.
 

#12

Joined Nov 30, 2010
18,223
Just need one heavy enough to carry 30A at 120v.
No you don't. You need a time delay function and a high current function. You might want to do it all in one part, but if you have enough room for two parts, don't paint yourself into a corner with your beliefs.;)
I have done thousands of, "field" repairs and some of them were very inconvenient.:( Do anything necessary to get the functions correct and the wiring safe. Then put the cover back on, and nobody will ever know the difference.:p
 

Thread Starter

nickit88

Joined Apr 3, 2017
30
No you don't. You need a time delay function and a high current function. You might want to do it all in one part, but if you have enough room for two parts, don't paint yourself into a corner with your beliefs.;)
I have done thousands of, "field" repairs and some of them were very inconvenient.:( Do anything necessary to get the functions correct and the wiring safe. Then put the cover back on, and nobody will ever know the difference.:p
Yeah, I have enough room to work with. Separate delay on the signal may be the ticket.
 
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