Relay

[Dusty MI]

I'm looking at a relay Schneider Electric #92S11D22D-12D
It has a 12 volt DC coil and the contacts are rated "Contact Amp Rating (Resistive): 30A @ 277VAC (NO), 3A @ 277VAC (NC)
It's a DPDT relay.
Whats the 3A VAC (NC) ?

I'm wanting to run an AC unit and an electric heat unit on the same circuit, both 120 volts.
I need the relay to control the heater and using the DT part will insure that both can not run at the same time.
This is for out motor home.

Thanks,
Dusty

 

[tlock0331]

(quoted from post at 15:42:54 09/01/18) I'm looking at a relay Schneider Electric #92S11D22D-12D
It has a 12 volt DC coil and the contacts are rated "Contact Amp Rating (Resistive): 30A @ 277VAC (NO), 3A @ 277VAC (NC)
It's a DPDT relay.
Whats the 3A VAC (NC) ?

30 Amps @ 277 Volts AC on the Normally Open side, 3 Amps @ 277 Volts AC on the Normally Closed side.

 

[Jaden]

It appears that they are distinguishing the amp capacity of the Normally Open and Normally Closed contacts. I looked at another information sheet and no difference is listed. What amp rating do you need?

 

[Steve@Advance]

That will be pushing the load on the 30A side for the air.

If the heat is 120v control/fan propane, it might handle it on the 3A side. But if it's resistive, no.

Would it be possible to use existing or add a NO relay to each appliance and control them with a common thermostat?

 

[John T]

Dusty, as you well know an AC unit is a highly INDUCTIVE load while electric strip heating is a pure RESISTIVE load. When an AC Inductive load starts up (IE NO contacts close) there's that high initial inrush current (maybe 5 or 6 x run current) but when the AC shuts off and the NO contacts return to open all the magnetic field stored energy is gonna cause some arcing across the contacts as they begin to open and that causes burning leading to pitting which is hard on contacts. I fear contacts rated at 3 amps might burn and pit due to arcing and heat upon shut down???? But if you just use the 30 A contacts that sounds okay ??? But an AC unit or an electric heater are both much higher current then 3 amps !!!!!!!!!!!!


I agree the 3A VAC NC is the rating for that NC set of contacts while the NO contacts are rated for 30 amp.


This make any sense to you an old sparky??? or am I all wet lol Ive been retired a longgggggggggg time remember so go easy on me lol

You still around Zephyrhills?? or Dade City ???

John T

 

[guido]

Hello Dusty MI,

Here is a link for the relay,

Guido.

Relay

 

[Dusty MI]

I'm used to seeing open frame relays and both the contacts on a DT relay were the same ratting.

This is for a 2250 watt electric furnace called a Toe Kick heater.
Normally LP is cheeper than electric for heat but when you have to deal in small amounts of LP at a time electric is cheeper and less hassle.

John T.
Yes we still winter in Zephyrhills. Stop by on your way thru.
I've lost my gizzard and have a little problem staying on my feet for a long time.

Dusty

 

[Texasmark1]

Did you plug that number into a www search engine?

 

[da.bees]

Most of the information you are getting is correct but some isn't taking into consideration how the heat & cool system operates. To take some of the confusion out of it,here's how the relay in question works. When at rest (12volts not being applied to coil) the set of contacts rated for 30 amp @ 277 volts are open and set rated for 3 amp @ 277 volts are closed(but depending on how thermostate and/or control switch is set,may or may not be carrying current at the time). You already know 30a contacts will operate cooling. When heat is called for,3amp contacts send a small 12 volt current to coil on time delay and fan relay(s). Time delay has it's own contactor that carry's 120 volts to resistive coils and fan. The relay doesn't have to be brand specific (you may never find same brand) it just has to have 12 volt coil plus same or greater ratings for contacts and of course the same NC/NO sequence. Any hvac supply house can fix you up or you can order it online.

 

[guido]

Hello Texasmark1,

It came right up when I did it. The exact number the manufacturer and the price,
I will go back to my nap now!
Guido.