Using proportional VALVE control to run a HEATER

Hello !
I have an Omron E5EK 1/8 DIN auto-tune control that is designed to operate a valve, by using an OPEN relay contact and a CLOSE relay
contact to run a motorized valve. It tracks the temp of the "fluid" via many different kinds of devices. In my case, I'm using a K-type thermocouple.
I'd like to use this unit to control a heater element.
So, my question is: Can you use the OPEN(valve) relay closure to control a heater element via either a SSR or mechanical relay ??
Obviously, the other contact, the CLOSE(valve) function has no application with respect to the heater element.
The other possibility would be to try to get the control software upgraded somehow to change it back to a standard control.
Bill Brachhold Gainesville, FL
Add pictures here
<% if( /^image/.test(type) ){ %>
<% } %>
<%-name%>
Add image file
Upload
The controller does not care whether you are adding heat electrically or by any other means. One contact opens when heat is needed, the other closes. Pick the one you need and connect it to the source of heat in any way convenient.
Walter.

Add pictures here
<% if( /^image/.test(type) ){ %>
<% } %>
<%-name%>
Add image file
Upload
Bill,
I think Walter is half right. The heat source does not matter to the controller. However, the control of that heat source matters very much to the controller. Your Omrom controller has three-state outputs, where none, either one, but not both of the outputs can be on. The primary tuning constants are deadband and hysterisis. Controlling an electric heater through a relay normally uses a signle output with the duty cycle calculated by the controller to maintain setpoint.
That said, I think your exisiting controller will work, but not as well as you might want it to. Your temperature will always be cycling, as the heater turns on at setpoint-deadband and turns off at setpoint- deadband+hysterisis. If hysterisis = 2 * deadband, the temperature will at least cycle about the setpoint.
Mike

Add pictures here
<% if( /^image/.test(type) ){ %>
<% } %>
<%-name%>
Add image file
Upload
If your heater element is controlled via a relay, then you can turn it on with the "open" signal. Depending on your relay and configuration you can either stop sending the "open" signal or send a "closed" signal to the relay to get it to turn the heater off.
You may find that you really don't need any more advanced control than this for most heating applications. A lot of heating controls are simply on-off.
Michael

Add pictures here
<% if( /^image/.test(type) ){ %>
<% } %>
<%-name%>
Add image file
Upload
Walter, Mike and Michael,
Thanks a million !! The info about deadband and hysteresis are invaluable.
As this thing is intended to control a brick-insulated kiln, and that 5-10 degree temp variations are insignificant, then I'm sure OFF/ON control will be fine.
As an aside, does anybody know of a website, or book, that explains controls like these in more detail ?? Not looking for a "dissertation" on controls, just a good book that covers the general aspects of the different kinds of controls.
Bill
Add pictures here
<% if( /^image/.test(type) ){ %>
<% } %>
<%-name%>
Add image file
Upload
It's a broad subject and there is much published material covering many aspects. Have a look at my site at www.driedger.ca for one view point. It doesn't cover basics, but does deal with industrial applications.
Walter.

Add pictures here
<% if( /^image/.test(type) ){ %>
<% } %>
<%-name%>
Add image file
Upload
Walter,
Nice site !! I will check ot out from work, where I have a high speed connection.
But, the Omron control continues to fight with me. It has a potentiometer input to get feedback about the position of the valve. Of course, a kiln doesn't have a "position indicator". I'm about ready to trash this one, and try something else.
Anybody got a cheap ramp/soak control suitable for heating ??
Bill
aspects. Have a look at my site at www.driedger.ca for one
Add pictures here
<% if( /^image/.test(type) ){ %>
<% } %>
<%-name%>
Add image file
Upload
Chromolux has a decent unit which would do what you need. Basically and sldc (single loop digital controller) will do.
You could just hook the potentiometer up to the same signal used to turn the heater on. That would amuse the dickens out of the unit, but it would serve the purpose. You might need a little signal conditioning for that.
Michael
wrote in message news:<7Ye_b.593247> aspects. Have a look at my site at www.driedger.ca for one
Add pictures here
<% if( /^image/.test(type) ){ %>
<% } %>
<%-name%>
Add image file
Upload
I've used Watlow F4 programmer/controllers with good success on industrial dryers. A lot of features for the money. I've aslo built dozens of kiln control systems, but they were not cheap.
Good Luck
wrote in message news:<7Ye_b.593247> aspects. Have a look at my site at www.driedger.ca for one
Add pictures here
<% if( /^image/.test(type) ){ %>
<% } %>
<%-name%>
Add image file
Upload

Polytechforum.com is a website by engineers for engineers. It is not affiliated with any of manufacturers or vendors discussed here. All logos and trade names are the property of their respective owners.