OT: WIKA Pressure Switches

dmmons

Member
Join Date
Sep 2011
Location
South Jersey
Posts
54
Not really a PLC question, but I know you folks have run across a lot of stuff in your collective experience:

I have a pressure switch with two normally closed contacts. When the pressure builds the needle moves a pin and it actuates the switches (breaks the contacts) as it reaches their respective setpoints. When I put an ohmmeter on the wiring terminals for each switch, I see some resistance (~1000 ohms) when i actuate the switches i lose all connectivity as expected.

However, when I run 24VDC through the switch and then actuate it, the circuit remains closed. It acts almost like it is latching itself.

I tested the switches with just a power supply and a light to remove any possibility of something being wrong with my control circuit. With the same results.

I have contacted the manufacturer and explained what I found. They said it sounds broken and I should return it. But it seems odd that two separate switches would be broken. I don't want to waste any time by swapping in a new set of pressure switches and having the same result.

Any ideas?
 
Not much anyway, there is a mention of them on the second page under options...

 Alarm contacts switches (magnetic or inductive)

This is all I have been able to find.
 
Wika part number should be something close to:
D-10-7-.....
This one is a Profibus model and I will have to work with it for an upcoming project.
The number you listed isn't a valid part number.
 
The switches need some power to work and have three contacts.
the switches are electronic and not simple mechanic.
give us a picture and we go on with your puzzle
 
Finally found some more information. Turns out the contacts for this particular switch are triacs, and the switches are made to work only with AC, not the DC I was putting through it.

I tested the switches with AC and voila...

Thanks for all of your help guys.
 
Last edited:

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