controll switch for solenoid valve

[themroc]

A stupid Question for a electrical engineer, but it comes from a chemical engineer.
I intend to switch a solenoid valve on/off. To do this I have got a data aquisition module here I can trigger 0 or 10 Volts output.

The solenoid valve I have got is switched by a 24Volt signal
(0 vot closed / 24Volt open).

I have got a 24 Volt power supply connecting this directly would mean the valve is always open. What I am looking for is a switch whichj is triggered by my 0 to 10 Volt data aquisition, so 0 Volt means 0 Volt supply closed valve and 10 Volt means switch open and 24 Volt supply.

I am just looking for the name of such a switch and mybe some suppliers preferably in the UK.

 

[dbaird]

Check:

http://europe.hbc.honeywell.com/products/ecatdata/pg_mce3.html

David Baird

Sr Controls Designer
EET degree.
Journeyman Electrician.

 

[waross]

You are looking for a "relay".

Bill
--------------------
"Why not the best?"
Jimmy Carter

 

[themroc]

Thanks,
I was told that I should go for a solid state relay in order to avoid backcurrent???
What is the principle of both relay types??

 

[themroc]

Just a Question to the experts, would this one do the job:

http://uk.rs-online.com/web/search/searchBrowseAction.html?method=getProduct&R=3776097

Thanks
Peter

 

[ScottyUK]

You need a relay which will switch a DC load . The one you linked to is designed for an AC load only. Try this one instead:

http://uk.rs-online.com/web/search/searchBrowseAction.html?method=getProduct&R=3763805

You should consider using a diode to protect the solid state relay output from the inductive load of the solenoid.


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If we learn from our mistakes I'm getting a great education!

 

[OperaHouse]

That would work IF your valve is operated with 24V AC and the current it needs is under that of the relay specification.

 

[themroc]

Thanks scottyUK, that sounds good.
Where exactly do I connect the diode to. I presume I will have a plus and minus on the relay load output to my solenoid, do I have to connect the diode inbetween the plus connection or does it not matter.
What kind of Diode specification do I need?
(I just remember having heard somethin about dioded dates back to my school years!!!)

 

[jraef]

Better yet, first determine for sure whether the solenoid requires 24VAC or 24VDC. Both are common.

 

[ScottyUK]

Good point jraef - we don't know what type the solenoid is! 24V AC is pretty unusual in the UK, and I guessed the OP was from the UK from the link he posted. I should not assume: we all know what that makes.



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If we learn from our mistakes I'm getting a great education!

 

[themroc]

The valve is 24VDC. With this voltage it is rated at 12W.
I was investigating what kind of Diode to use and where to connect to, but the information out there for a non electronic expert is quiet owerwhelming.
So maybe someone of you can help. What kind of Diode do I need for this application.
I had a look on RS and I opted for this one:

http://uk.rs-online.com/web/search/searchBrowseAction.html?method=getProduct&R=6289546#header

Would this work?

 

[OperaHouse]

Since the valve is 24V DC you can not use the SSR you pictured. They make the same thing in a DC version. Any 1A 50V or higher diode can be used as a snubber parallel with the relay. The banded side goes to the positive supply.

You could get away with just using a 24V AC transformer instead of having to buy a 24V DC power supply. Just use a 1A 100V or higher diode bridge. Connect the + & - leads to the valve. The AC leads go to the SSR and transformer. With this setup you can use the AC SSR that was pictured.

 

[themroc]

Thanks OperaHouse, good recommendatyion but we have got already the 24VDC power supply.
Just one Question you say the diode has to go in parallel. Just to claryfy. I would connect the + from my DC Power supply to the + of the SS relay and than to the + of the solenoid valve and I presume the minus of the DC Power supply directly to the minus of the solenoid valve.
Then by introducing the Diode I would again connect the + of my DC Power supply + of the SS relay than and this would be different I would connect the banded side to the positive connection of the SS relay and the other side of the Diode goes to the positive (+) of the Solid state relay.
Is that correct (sorry for the simple Question).
Thanks in advance

 

[ScottyUK]

Hi Opera,

Have a look at the link in my last post: 6A @ 100V DC from the same range as themroc originally chose. More than adequate.

themroc,

The diode should be connected across the solenoid coil with the cathode - the end with the white line or coloured band - connected to the most positive end of the coil. That diode would do fine although a 1N4001 would be just as effective and a little cheaper.


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If we learn from our mistakes I'm getting a great education!