Hydraulic Valve Problem

Can anyone help with the folowing? - we want to drive a Danfoss hydraulic valve (PVG 32) with a analogue output signal from a PLC (MITSI or Siemens). The valve requires a proportional signal of 6V to 18V with 12V being the neutral position. (12 to 6V being one direction; 12 to 18V being the other). Can this be done from a standard module?

Thanks in anticipation.

No.
Get an amplifier for that servo valve that takes 0-10, or -10/0/+10.

The amplifier for driving the valve also applies a dither (an overlayed PWM signal) to the voltage to the valve coil to overcome the effects of static friction on the valve spool. Also the current draw is typically higher than what a PLC will deliver.

Hello,


The PVG32 is a proportional valve made for mobile applications. It works with 25-75% of the supply voltage. In mobile applications the only thing that you can be sure about is that you do not have 24V. It can vary depending on battery condition, engine start etc. This way it is possible to make easy joystick control etc. Sauer Danfoss has their own PLC(Plus1) that can interface these valves directly.

However this makes life more difficult when usinga a traditional PLC with 0-10V signal. It is not as easy a getting an amplifier that takes 0-10, or -10/0/+10.

We been doing some tricks with 12V variants of the PVG. This requires 3-9V. Just make sure that the supply voltage is accurate to 12.00V.

You do not need a PWM signal for this valve and the control voltage only require

Is the PVG the right valve?

Thanks for the input everyone.

We have been using the PVG 32 proportional valves with electrical actuators for about 5 years in a petrochem environment. They have worked very well for us. Note that this is not a mobile application, so we don't have the problems some people have mentioned with unregulated battery power -- the regulated 24VDC power supply does just fine.

Here's how we control it:

The PLC's digital output module directly drives the actuator's POWER input (pin 1). Energized when operating the valve, de-energized when valve is to be at neutral position.

The PLC's 4-20mA output module feeds a signal conditioner. The signal conditioner output (0-24VDC) is wired to the actuator's CONTROL input (pin 2). Lately we have used the AGM Electronics 4-20mA in/0-24VDC out module, AUX 4000-22. Here's how the signals worked out:

   

       SIGNAL 

 PLC    COND.    VALVE

 OUT     OUT    POSITION

 8mA  =   6V  =  -100%

12mA  =  12V  =     0%

16mA  =  18v  =  +100%

It's been working reliably ever since it was installed.