OT: WIKA Pressure Switches - PLCS.net

dmmons · September 13th, 2012, 01:50 PM

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?

bernie_carlton · September 13th, 2012, 02:02 PM

Can you supply the specific model number?

dmmons · September 13th, 2012, 02:09 PM

52241238

Thanks Bernie

bernie_carlton · September 13th, 2012, 02:22 PM

I don't see anything close to that model number on their site

Can you find it?

dmmons · September 13th, 2012, 02:26 PM

This is all I could find.

http://www.wika.us/upload/DS_PM_26X_34_en_us_15636.pdf

bernie_carlton · September 13th, 2012, 02:28 PM

That one doesn't have anything about output switches.

dmmons · September 13th, 2012, 02:33 PM

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.

bkottaras · September 14th, 2012, 01:26 AM

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.

shooter · September 14th, 2012, 03:51 AM

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

keithkyll · September 14th, 2012, 08:41 AM

Quote:

Originally Posted by dmmons

... When I put an ohmmeter on the wiring terminals for each switch, I see some resistance (~1000 ohms) ...

1000 Ohms is too high. This indicates it's electronic, and must be powered to operate correctly. An Ohmmeter is not enough.

dmmons · September 19th, 2012, 08:50 AM

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.

September 13th, 2012, 01:50 PM	#1
dmmons Member Join Date: Sep 2011 Location: South Jersey Posts: 54	OT: WIKA Pressure Switches 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?

September 13th, 2012, 02:02 PM	#2
bernie_carlton Lifetime Supporting Member + Moderator Join Date: Apr 2002 Location: Yakima, Washington Posts: 6,399	Can you supply the specific model number? __________________ Controlling outputs is the PLC's way of getting its inputs to change.

September 13th, 2012, 02:22 PM	#4
bernie_carlton Lifetime Supporting Member + Moderator Join Date: Apr 2002 Location: Yakima, Washington Posts: 6,399	I don't see anything close to that model number on their site Can you find it? __________________ Controlling outputs is the PLC's way of getting its inputs to change. Last edited by bernie_carlton; September 13th, 2012 at 02:31 PM.

September 13th, 2012, 02:28 PM	#6
bernie_carlton Lifetime Supporting Member + Moderator Join Date: Apr 2002 Location: Yakima, Washington Posts: 6,399	That one doesn't have anything about output switches. __________________ Controlling outputs is the PLC's way of getting its inputs to change.

September 14th, 2012, 03:51 AM	#9
shooter Member Join Date: Sep 2002 Location: duketown Posts: 2,711	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 __________________ shooter@home.nl skype shooter paul.deelen Computer Shooter Paul Deelen J. Wassenaerstraat 29 NL 5224 GG 's-Hertogenbosch +31653300739



This board is for PLC Related Q&A ONLY. Please DON'T use it for advertising, etc.
*Try our online PLC Simulator- FREE. Click here now to try it.*

September 13th, 2012, 02:09 PM	#3
dmmons Member Join Date: Sep 2011 Location: South Jersey Posts: 54	52241238 Thanks Bernie

September 13th, 2012, 02:26 PM	#5
dmmons Member Join Date: Sep 2011 Location: South Jersey Posts: 54	This is all I could find. http://www.wika.us/upload/DS_PM_26X_34_en_us_15636.pdf

September 13th, 2012, 02:33 PM	#7
dmmons Member Join Date: Sep 2011 Location: South Jersey Posts: 54	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.

September 14th, 2012, 01:26 AM	#8
bkottaras Member Join Date: Oct 2005 Location: Chicago Posts: 1,744	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.

September 19th, 2012, 08:50 AM	#11
dmmons Member Join Date: Sep 2011 Location: South Jersey Posts: 54	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 by dmmons; September 19th, 2012 at 08:50 AM. Reason: misspelling

Currently Active Users Viewing This Thread: 1 (0 members and 1 guests)

Thread Tools
Show Printable Version Email this Page
Display Modes
Linear Mode Switch to Hybrid Mode Switch to Threaded Mode

Similar Topics
Thread	Thread Starter	Forum	Replies	Last Post
Looking for a strategy to decelerate a hydraulic cylinder	Tubularfab	LIVE PLC Questions And Answers	56	February 8th, 2012 05:22 PM
Injection Molding Control	Archie	LIVE PLC Questions And Answers	40	October 7th, 2010 03:01 AM
Hydraulic fixed deplacement pump and VFD.	MrQ	LIVE PLC Questions And Answers	13	August 30th, 2006 04:31 PM
Analog Output follow up	BoxerBrats	LIVE PLC Questions And Answers	33	March 22nd, 2005 12:00 AM
Pressure-Position	Orn Jonsson	LIVE PLC Questions And Answers	5	July 9th, 2002 04:44 PM