Need help driving Hydraulic valve

[Erik A]

I have a situation with an old Barber Colman Maco 8000 controller. The one module in question has 4 analog outputs but they are not rated hi enough to handle the current draw of a proportional hydraulic valve. What I was wonder is it possible to use a PIC microcontroller or something similar to drive the valve. Use 4 analog inputs on the Pic and then program 4 analog outs to follow the same voltage as the input, just have a better current tolerance on the Pic outputs. Or is there any other way? just to do it a cost effective as possible. Any help would be great

 

[dash]

Unless I am missing something you should have a proportional valve driver between your output (4-20mA/0-10VDC, +/-10VDC, etc). The driver will provide other CRITICAL functions such as dither, biasing, etc. Check the website of the manufacturer of the valve you have and there should be several options depending on the age of the valve. The typical options are onboard electronics (usually ordered with the valve) or most of the off board electronics come in a euro-card format and you also have to purchase a card holder to mount it in your panel (or out close to the valve if it is a long cable run). Also ask about options like enable signals (can be very important if you want to make sure the valve stays at a null position when you are not sending a control signal).

Hope this helps,

Darren

 

[Waleye]

Erik A,
Dash is correct. There should be a valve driver between the Maco and the valve. Give me some more info about the valve and I can steer you in the right direction

 

[Erik A]

Thanks guys, I guess what I am looking for is a digital driver not an analog driver. That is why i was wondering if one could build one perhaps with a PiC 16f877 something that has a number a A/D and D/A ports. I just want something for the lowest cost possible. If there is a cheaper Digital driver that would be great. But I don't want to go with analog, since I currently do and they cause me to much inconsistency.

 

[Pierre]

.....But I don't want to go with analog, since I currently do and they cause me to much inconsistency.....

Seems to me that you are going to perhaps add some problem rather than removing them. Using a PIC is nice for a student project but for a plant you must try and use what is off-the-shelf- and known to be standard in the industrie.

Dash has the good approach on this. Listen to him. Thinck of the next guy who will have to troubleshoot this system. He may not be has good has you with MCUs.

 

[Peter Nachtwey]

Just curious

What do you expect the PIC chip to do? A PIC microcontroller can't output enough power to directly power unless it has an amplifier.

 

[jonton]

test

 

[jonton]

Maco systems I have seen have their own maco card to drive the speed and pressure valve. Tuning is done on the screen with a password. If it used to work, what happened then. Did you change the valve type? If you cant get enough current to the valve to achieve required speeds or pressures I would check for dirty valve or have pump tested for rated flow at max pressure.