2 vdc and 10 vdc signals generate

Kataeb · Nov 19, 2014

i need to control a valve with analog input 2 to 10 vdc, without using any analog output device, because the control does not contain any automation.
to keep it simple, i am using relays which should switch on 2 vdc (valve off) or 10 vdc (valve on). so i am looking for a simple circuit to generate 2 vdc and 10 vdc signals.

Saffa · Nov 19, 2014

Why use an expensive valve that has an analog positioner in the first place? But if that's what you've got, then a simple voltage divider using two potentiometers will work. Put legs 1 and 3 across your standard 24V DC and adjust until leg 2 gives you 2 or 10V. Then switch using relays. It's messy but should work ok. Size the pots so they have a couple mA flowing them but double check the wattage to make sure you don't have them running too hot.

nonuke · Nov 19, 2014

I think you only need to sen 10V to open and 0V to close the Valve.

The 2VDC corresponds to the 4mA conversion into Voltage with the help of a resistor.

danw · Nov 19, 2014

Any valve positioner that takes an analog input signal will have a 'fail-safe' setting that becomes active should the postioner detect that it has 'lost' the input signal.

That's one of the reasons a 'live-zero' signal like 4-20mA or 1-5Vdc or 2-10Vdc, where zero volts means an open circuit or loss of input signal, is so widely used in industrial controls.

This could be relevant should you decide to use 0V to close the valve, because 0V might 'fail-safe' as a fully open condition.

nonuke · Nov 20, 2014

The 2V or the 4mA are relevant when you are reading the analog input and I agree with danw.

If you just want to close the valve (analog output), what is the difference sending 2V or 0V. If you send 0V you don't have to create a voltage divider.
If you send only 2V, the valve might not close completly!!

osmanmom · Nov 20, 2014

depend of application

2V sometimes use to allow small value to let machine no to stop.

nonuke · Nov 20, 2014

osmanmom said:
depend of application

2V sometimes use to allow small value to let machine no to stop.

Kataeb only wants to open and close a valve like an ON/OFF device.

osmanmom · Nov 20, 2014

hope Kataeb give info what brand/model he used.

holyhobgoblin · Nov 20, 2014

What type of valve and whats the application?

Depending on the above you could simply switch a 10 volt supply, but would highly recommend replacing coil with 24 volts DC type, if this is at all possible.

Kataeb · Nov 20, 2014

please check attached files. thanks

osmanmom · Nov 20, 2014

Base on user manual and your attachment you NOT need to use resistor,

if you check again the user manual the DIP Switch S7 & S8 provide if any

signal input fail the valve will fully closed if you configuration

S7 -OFF and S8-ON, this reflex to your relay Contact NO, Deactived the relay.

if the control no require RESET.

others option you can use 5V signal as signal input on DIP Switch S1 -OFF

and S2 -OFF for fully open via relay contact.

What you need the 24VDC supply convert to 5VDC using fix Voltage IC e.g. LM7805

Use 0.1AMP fuse on 24VDC incoming

only use 1 relay and NO

if your responbiltiy to take care the safety and asset.

shooter · Nov 22, 2014

You can use the voltage source in the honeywell, but your scheme is also working fine.

2 vdc and 10 vdc signals generate

Kataeb

Member

Saffa

Member

nonuke

Member

danw

Lifetime Supporting Member

nonuke

Member

osmanmom

Member

nonuke

Member

osmanmom

Member

holyhobgoblin

Member

Kataeb

Member

osmanmom

Member

shooter

Member

Similar Topics