12VAC smal ice cube relay
12VAC smal ice cube relay
(OP)
We have some new equipment that is using 12VAC relays powered by 16.5VAC. This is over 30% designed coil voltage. The relays are all hot. The wiring matches the drawing. Is this in the range of voltage tolerance? I searched the internet but was unsuccessful to find the answer so here I am where I get factual and accurate advice.





RE: 12VAC smal ice cube relay
Gunnar Englund
www.gke.org
--------------------------------------
100 % recycled posting: Electrons, ideas, finger-tips have been used over and over again...
RE: 12VAC smal ice cube relay
RE: 12VAC smal ice cube relay
We can cough up some solutions for helping the relays but I would imagine other devices,(not relays), are suffering in this scheme also. So it may make more sense to fix the 16.5V once, instead of five or ten times.
Keith Cress
Flamin Systems, Inc.- http://www.flaminsystems.com
RE: 12VAC smal ice cube relay
How the circuit is installed:
The circuit starts at a unregulated 24VAC transformer and one side of the secondary is tied to ground. The 24VAC travels through a diode and current limiting resistor. It then goes to the probe and then back to the 12VAC relay and then to ground. This causes the relay to energize which then pulls up a set of holding contacts which puts 24VAC in the same circuit described before but it bypasses the diode. If the probe touches ground then ground is on both sides of the relay and it drops out sending the fault and opening the holding contacts.
This is a sub-assembly not manufactured by the equipment OEM and I have written them but did not get a response.
I think the circuit is designed wrong and that the diode should never by bypassed. Does this sound right?
RE: 12VAC smal ice cube relay
Does this unit have any approvals on it?
respectfully
RE: 12VAC smal ice cube relay
RE: 12VAC smal ice cube relay
Another option is to put a zener somewhat over 13V (because of half wave) on the relay coil. This will throw the excess heat into the resistor instead of the relay. Theb you will have resistors burning out!
RE: 12VAC smal ice cube relay
RE: 12VAC smal ice cube relay
Keith Cress
Flamin Systems, Inc.- http://www.flaminsystems.com
RE: 12VAC smal ice cube relay
RE: 12VAC smal ice cube relay
There could also be NO good reason... LOL Maybe they had 24V transformers and went with them. Frankly a failure prone safety system is not a safety system if things start burning or failing. And things will - as you have no doubt surmised.
Keith Cress
Flamin Systems, Inc.- http://www.flaminsystems.com
RE: 12VAC smal ice cube relay
RE: 12VAC smal ice cube relay
RE: 12VAC smal ice cube relay
Gunnar Englund
www.gke.org
--------------------------------------
100 % recycled posting: Electrons, ideas, finger-tips have been used over and over again...
RE: 12VAC smal ice cube relay
Respectfully
RE: 12VAC smal ice cube relay
Does equipment sometimes come with the wrong relays installed?
It happens.
Respectfully
RE: 12VAC smal ice cube relay
RE: 12VAC smal ice cube relay
respectfully
RE: 12VAC smal ice cube relay
RE: 12VAC smal ice cube relay
RE: 12VAC smal ice cube relay
One test will not fit all. It sounds as if your relay was highly resistive. Try your test with a relay with a higher ratio of reactance to resistance and you may get different results.
respectfully
RE: 12VAC smal ice cube relay