0
\$\begingroup\$

I looking to replace a blown power relay on a convection oven. The part is no longer available. I can't conceive of replacing such an expensive asset just because I can't find a $30.00 part. (Thanks, GE!)

I'm looking for a suitable replacement relay. The switched power is 240V with two output poles feeding (from the same switch) a 21A /5000W cleaning circuit and a 14A / 3000W heating circuit. Existing relay is a SPST-NO (single pole, single throw, normally open) configuration. I'm trying to determine the correct coil amperage. The coil is on a 120V circuit.

Questions: 1) without a published spec, how can I determine the correct coil amperage requirement? 2) the existing relay has the typical diode across the coil terminals -- how do I calculate the correct diode on the new coil? I think I can calculate the impedance of the coil solenoid -- is there a typical adjustment factor that is used to figure out the diode? Would rather not experiment too much with this. There is a diode on the existing relay, but I think I'm correct in assuming that IT'S capacity is irrelevant since it's unique to the old relay's solenoid impedance. 3) This seems like a dumb question, but which way should the diode point?

Just an aside, my local appliance tech will help with the replacement. I'm wary of messing with 220V.

relay-backside

relay-frontside

\$\endgroup\$

closed as off-topic by Brian Carlton, Null, Daniel Grillo, Nick Alexeev Oct 24 '15 at 6:31

This question appears to be off-topic. The users who voted to close gave this specific reason:

  • "Questions on the repair of consumer electronics, appliances, or other devices must involve specific troubleshooting steps and demonstrate a good understanding of the underlying design of the device being repaired. See also: Is asking on how to fix a faulty circuit on topic?" – Null, Daniel Grillo, Nick Alexeev
If this question can be reworded to fit the rules in the help center, please edit the question.

  • 1
    \$\begingroup\$ There is no diode visible in your pictures. I see what looks like a MOV or maybe a capacitor, but no diode. \$\endgroup\$ – JRE Oct 22 '15 at 18:22
  • \$\begingroup\$ I'm thinking I just power it back up, stick an ammeter on the coil circuit, and read it. Carefully. \$\endgroup\$ – TimBaynes Oct 22 '15 at 18:33
  • \$\begingroup\$ Does that mean there's no diode, just the blue thing? \$\endgroup\$ – JRE Oct 22 '15 at 18:35
  • 1
    \$\begingroup\$ I keep looking at the picture and thinking it is a thermally operated switch but I expect the solenoid coil is there, just hidden from view. \$\endgroup\$ – KalleMP Oct 22 '15 at 20:53
  • 1
    \$\begingroup\$ Y'all know how it goes -- the techs as well as customer support are generally brain-dead (either by nature or by policy). There are no substitutes, officially. Anywhere... However, I did a little reverse engineering, found circuit diagrams for another make of range and, lo and and behold, it uses the same relay albeit under a different part number. That part is actually available, and I just ordered two of them.. :-D \$\endgroup\$ – TimBaynes Oct 22 '15 at 22:29
1
\$\begingroup\$

Its a MOV, not a diode. Read the data behind (probably 275 volt or similar, size is also important, measure the diameter) or when buying a new contactor look if it has in-bult suppressor, or just unsolder it and reuse it. Any power contactor with rated current contacts will do the job, as you said 21+14 = 35A or more some standard 40A, or two separated contacts 25A...
The correct coil amperage isn't important (the coil voltage is important), it will be almost the same for the same size of contactor.

\$\endgroup\$

Not the answer you're looking for? Browse other questions tagged or ask your own question.