Help setting up OMRON Temp Controller

M

MarkMc

Guest
Hi

I just got an OMRON temperature controller, model number EJCS-R1KJX.
The manual which comes with it is pathetic - a duff translated affair.

I want to use this unit to control fermentation temperatures for my
home brewery. This involves switching on a cooling source if too hot,
and switching on a heatin source if too cold to keep a stable
temperature.

I have a couple of questions about setting up the controller.

I'm not sure if i need to use on/off mode or PID - I don't know what
PID actually is. Can somebody explain?

The unit provides two relay outputs one for control and the other for
alarm. I assume I need to provide my own relay contact
protection/suppression?

Also, I accidentally bought the wrong model. I wanted the RTD model
but got the thermocouple model - eBay one off, so no chance to change
it. I know nothing about thermocouples. It looks like type K's are
easy for me to get, but I read something about "compensating
conductors" - what's this all about?

Regards,
Mark
 
"MarkMc" <mmcnospam@yahoo.co.uk> wrote in message
news:1121243477.409062.275020@g14g2000cwa.googlegroups.com...
Hi

I just got an OMRON temperature controller, model number EJCS-R1KJX.
The manual which comes with it is pathetic - a duff translated affair.

I want to use this unit to control fermentation temperatures for my
home brewery. This involves switching on a cooling source if too hot,
and switching on a heatin source if too cold to keep a stable
temperature.

I have a couple of questions about setting up the controller.

I'm not sure if i need to use on/off mode or PID - I don't know what
PID actually is. Can somebody explain?

The unit provides two relay outputs one for control and the other for
alarm. I assume I need to provide my own relay contact
protection/suppression?

Also, I accidentally bought the wrong model. I wanted the RTD model
but got the thermocouple model - eBay one off, so no chance to change
it. I know nothing about thermocouples. It looks like type K's are
easy for me to get, but I read something about "compensating
conductors" - what's this all about?

Regards,
Mark

You have a lot of questions but nothing specific.
Click to expand...
Here is a place to learn about PIDS; http://www.expertune.com/tutor.html
Type K thermocouples are easy to find.
Regards,
Tom
 
MarkMc wrote:
Hi

I just got an OMRON temperature controller, model number EJCS-R1KJX.
The manual which comes with it is pathetic - a duff translated affair.

I want to use this unit to control fermentation temperatures for my
home brewery. This involves switching on a cooling source if too hot,
and switching on a heatin source if too cold to keep a stable
temperature.

I have a couple of questions about setting up the controller.

I'm not sure if i need to use on/off mode or PID - I don't know what
PID actually is. Can somebody explain?
Click to expand...
PID stands for Proportional, Integral, Derivative. This describes the
three responses to process error that add (or multiply) to make up the
controller output. Proportional response alters the output without
regard to the frequency of the error. It is set either with a
proportional gain constant or a proportional band constant (100/gain).
Integral response is a low pass filter type response that
essentially ignores short duration errors, but accumulates a large
response if an error persists. It may be set with an integral gain or
an integral time (reciprocal of gain). Derivative response is a sort
of high pass filter that responds stronger if the error changes
quickly. It is also set by either a derivative gain or time.

On/off mode just converts the PID linear output to pulse duty cycle,
useful for things like resistance heaters or solenoid valves.
Continuous PID control is for things like control valves that vary
stem position with signal (usually 4 to 20 mA = full closed to full
open or vice versa).

For a basic tutorial on PID tuning I wrote, based on watching a time
based chart of process measurement and output, see:
http://www.tcnj.edu/~rgraham/PID/popelish.html

The unit provides two relay outputs one for control and the other for
alarm. I assume I need to provide my own relay contact
protection/suppression?
Click to expand...
That is the safest bet. I doubt that you can both heat and cool with
this controller. Those take dual control outputs. You may need a
dual output controller that splits the output range in half, with one
output controlling the amount of heating and the other output
controlling the amount of cooling. You may get to use RTDs, yet.

Also, I accidentally bought the wrong model. I wanted the RTD model
but got the thermocouple model - eBay one off, so no chance to change
it. I know nothing about thermocouples. It looks like type K's are
easy for me to get, but I read something about "compensating
conductors" - what's this all about?
Click to expand...
You have to get thermocouples that match one of the set up choices for
your controller.

Thermocouple signals are produced when a wire passes through a
temperature gradient. Different alloys produce different voltages, so
bringing a pair of dissimilar types from a couple (electrical
connection between them) from the process temperature to the
controller will produce a small voltage related to the difference
between those two temperatures. The controller measures its own
temperature and corrects for that, so that it can infer just the
process temperature. If that pair of wires has to pass through
significant temperature variation (relative to the controller) on its
way between these two points, the two special alloys have to be
maintained the whole way, for this process to work. So you normally
use thermocouple extension wire if the controller is further away than
the lead length, rather than using copper extension wire.
 
Thanks for the detailed responses, I've very grateful. I'll have a
read of the link too.

From what I've read about my specific unit, it has relay contacts
rather than a 12v output. How does PID work with this?
Click to expand...

I was assuming I could use the main control as the cooler and the alarm
as the heater driver. What am I missing here? IIRC the unit will let
me set absolute values for both. In reality, I'll probably need to
drive a cooler in summer, and a heater in winter, but it would be
better to be able to control both, as the temperature can drop quite a
bit over night in summer. Perhaps good insulation can take care of
temperature drops over night.

Regards,
Mark
 
"MarkMc" <mmcnospam@yahoo.co.uk> wrote in message
news:1121334195.470566.252750@g49g2000cwa.googlegroups.com...
Thanks for the detailed responses, I've very grateful. I'll have a
read of the link too.

From what I've read about my specific unit, it has relay contacts
rather than a 12v output. How does PID work with this?

I was assuming I could use the main control as the cooler and the alarm
as the heater driver. What am I missing here? IIRC the unit will let
me set absolute values for both. In reality, I'll probably need to
drive a cooler in summer, and a heater in winter, but it would be
better to be able to control both, as the temperature can drop quite a
bit over night in summer. Perhaps good insulation can take care of
temperature drops over night.

Regards,
Mark

I use a modified Ranco mounted to a box with a Peltier cooling/heating
Click to expand...
device. I set the set points for both cool and heat. A DPDT relay reverses
polarity.
Most units have a "window" capability if they are classified Heat/Cool.
Google 'Rec Crafts Brewing' , many of us have described what you are doing
many times.
Tom
 
Hi Tom

I am a regular on r.c.b, but for some reason, I didn't think to post my
question there.

Regards,
Mark
 
MarkMc wrote:

From what I've read about my specific unit, it has relay contacts
rather than a 12v output. How does PID work with this?

I was assuming I could use the main control as the cooler and the alarm
as the heater driver. What am I missing here?
Click to expand...
The PID operating a relay output produces a pulse duty cycle
proportional to the PID numerical output. That is, if the output is
50%, the pulse will have equal on and off times (usually, you set the
period as part of the set up). The alarm relay outputs come on
continuously, any time the process exceeds some value you specify. No
PID algorithm is involved in them.

IIRC the unit will let
me set absolute values for both. In reality, I'll probably need to
drive a cooler in summer, and a heater in winter, but it would be
better to be able to control both, as the temperature can drop quite a
bit over night in summer. Perhaps good insulation can take care of
temperature drops over night.
Click to expand...
Bidirectional control is hard with a single pulsed output.

What sort of hardware are you using for heating and cooling (hot and
cold water valves to a heat exchanger, resistive heating element and
peltier cooler, heat pump)?
 
Ah, now it's starting to see what how these controllers work. Im not
sure pulsing on my chiller is a good idea.

For heat I'm intending to use a standard homebrewers/wine makers heat
belt (400W IIRC) and for chilling its called a recirculating flash
chiller. These are used in pubs/bars to chill beer or beer lines to
stop the beer frothing. Basically the chiller is a smal refridgeration
unit, which chills a line which passes through it (via heat exchanger).
I intend to use it to pump (build in to unit) coolant (water) through
some 8mm copper pipe, in to my fermenter which has a coil (another heat
exchanger), and returns back to the unit.
 
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