how to wire relay with nc pressure switch?

Printed From: the12volt.com
Forum Name: Relays
Forum Discription: Relay Diagrams, SPDT Relays, SPST Relays, DPDT Relays, Latching Relays, etc.
URL: https://www.the12volt.com/installbay/forum_posts.asp?tid=126785
Printed Date: May 18, 2024 at 8:39 AM

Topic: how to wire relay with nc pressure switch?

Posted By: 3.0turbo
Subject: how to wire relay with nc pressure switch?
Date Posted: March 30, 2011 at 10:31 AM

Im a tard, how to wire relay with a NC pressure switch ?

switch closed until desired pressure, when switch is open, I need a 12v signal via a relay when NO

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FASTTIME DESIGN

Replies:

Posted By: oldspark
Date Posted: March 30, 2011 at 4:58 PM

Ah - a "failsafe" design (as I use for car thermo fans, and want to use for oil pressure except the switch costs $75 instead of under $10 for the NO version!)

A changeover relay (SPDT).
12V to #30 and output from NO contact 87a.
The NC switch energises the relay hence holding off 12V from 87a.

The considerations (limitations?):
- It is not passive (the relay is energise for the output (alarm etc) to be "off".
- You need some upstream master switch to disconnect power from the relay contacts (#30 etc). (EG - in the car, it's the IGN relay.)

Posted By: 3.0turbo
Date Posted: March 30, 2011 at 5:42 PM

Austrailia , I have customers in Ballarat.

I get the idea, however I need the relay to turn "on the consumer" as the NC switch opens, diagram helps.

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FASTTIME DESIGN

Posted By: oldspark
Date Posted: April 01, 2011 at 4:31 AM

Hmmm - it seems we got censored elsewhere...

But as I said, you supply a diagram of what you have and I'll modify....
But I thought the description (in this or the other thread) would suffice!