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PID challenge!
scareyourpassenger
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Posted on 01/20/2014 9:51 AM
I am faced with quite a challenge and I am not sure how to go about configuring my PID for control of my Ambex ym-2.

The Ambex has two controllable valves. A Honeywell control valve that can be turned on or off with a relay type control from the PID and is used for making sure the burners are safely lit and to control the on and off flow of the gas. The second valve is a variable valve that is used to control the flow of gas and can be adjusted via a 0-10volt signal.

The issue that I have is that when the second valve is on a low setting, all the buttoners won't light. So for cases where the flames need to be turned off to drop the temperature, it will need to turn on the Honeywell valve, apply full voltage via the second valve to be lit and then drop the pressure to make sure it doesn't overshoot the set point.

This may seem like far more than a pid can handle but I have quite a bit of flexibility within the pid units that I have. If required I can run up to 8 control loops, 8 inputs and 14 outputs, apply math functions, many alarms and actions based off events. I am new to PIDs so any guidance would be greatly appreciated.

Here is a link to the manual for the pid units I have. The primary is a RMC3F1F1F1NA1AA while the second is a RMC1 with similar outputs.
The manual can be found here. http://www.instru...Manual.pdf

Thanks in advance!
 
alexcampbell
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Posted on 01/20/2014 10:26 AM
I suspect the reason that your burners won't light is that solenoid valves need a higher current to begin opening than to stay open. you would probably have to give them a bit of a "Kick" to turn on. I would look at wiring in a voltage boost of some sort that comes on with your ignition system to increase the voltage to the variable soloenoid while the igniter is engaged. What type of solenoid is the variable one?
 
allenb
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Posted on 01/20/2014 10:49 AM

Quote

scareyourpassenger wrote:

The issue that I have is that when the second valve is on a low setting, all the buttoners won't light. So for cases where the flames need to be turned off to drop the temperature, it will need to turn on the Honeywell valve, apply full voltage via the second valve to be lit and then drop the pressure to make sure it doesn't overshoot the set point.



Here's some info that might be helpful from a recent post on the YM2

http://forum.home...post_48640

Allen
1/2 lb and 1 lb drum, Siemens Sirocco fluidbed, presspot, chemex, cajun biggin brewer from the backwoods of Louisiana
 
scareyourpassenger
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Posted on 01/20/2014 10:56 AM

Quote

alexcampbell wrote:

I suspect the reason that your burners won't light is that solenoid valves need a higher current to begin opening than to stay open. you would probably have to give them a bit of a "Kick" to turn on. I would look at wiring in a voltage boost of some sort that comes on with your ignition system to increase the voltage to the variable soloenoid while the igniter is engaged. What type of solenoid is the variable one?


To make sure it isn't a config issue, I have used the Ambex supplied controls to make sure it wasn't an electrical issue. There just isn't enough gas flow for the pilot to reach the additional burners.
 
scareyourpassenger
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Posted on 01/20/2014 10:57 AM

Quote

allenb wrote:

Quote

scareyourpassenger wrote:

The issue that I have is that when the second valve is on a low setting, all the buttoners won't light. So for cases where the flames need to be turned off to drop the temperature, it will need to turn on the Honeywell valve, apply full voltage via the second valve to be lit and then drop the pressure to make sure it doesn't overshoot the set point.



Here's some info that might be helpful from a recent post on the YM2

http://forum.home...post_48640

Allen


Thanks, I am familiar with that thread, just don't know the best way to tackle the issue given the controls I have available.
 
tamarian
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Posted on 01/20/2014 12:32 PM
Is this a stock setup, or modified setup? If modified by replacing PID and/or valves, you might need to check the spec of each.

Use a multimeter to check voltage and/or current being sent to the valve, to rule out signal issues.

The valve manuals might come in handy, to see if they need a calibration procedure, or a cleaning procedure.
Wa'il. 1 Kg PID'ed gas-fired fluid bed roaster, GS/3MPS, K10F
 
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allenb
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Posted on 01/20/2014 7:43 PM
Another obvious thing to confirm is that your regulator is putting out the minimum pressure needed by the gas valve components in your roaster. Is there a port for attaching a gauge. From what I've read on typical low pressure regs for your roaster you should have around 11" WC which is around 4/10 of a psi.

Allen
1/2 lb and 1 lb drum, Siemens Sirocco fluidbed, presspot, chemex, cajun biggin brewer from the backwoods of Louisiana
 
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