PID Loop Setup
PID is the tuning parameters entered for each Process Variable loop. The loop value can either be Loop 1, Loop 2, or Loop 3.
Prop Band (0 for On/Off)
This is the proportional band field. P = Proportional (Prop Band). This is a field in which you want to stay around the setpoint.
The range 0 – 999.0
Reset
This is the reset field. I = Integral (Reset). This is the actual temperature being monitored over a period of time and then averaged to keep within the Proportional band. The reset is in repeats per minute. This affects the output of the controller. It will be proportional to the amount of time the error is present. This helps to eliminate offset.
The range 0 – 100.00
Rate
This is the rate field. D = Derivative (Rate). This is the sudden change or rate in the temperature. This rate is in minutes. This affects the controller output which is proportional to the rate of change of the measurement and will control the amount of output by time restraints. Thus derivative takes action to inhibit more rapid changes of the measurement than proportional action. Derivative is often used to avoid overshoot.
The range is 0 – 100.00. The rate is not typically used for heating/carbon
Mode
This is the mode of the loop.
The values are: Dual Reverse, Single Reverse, Dual Direct, or Single Direct.
Dual – This has two output relays which can increase and decrease to achieve your SP.
Single – This has one relay which works in only one direction to achieve your SP.
Direct - If the PV - SP equals a positive number and the output would bring the PV down toward setpoint that is direct.
Reverse – If the PV - SP equals a negative number and the output would bring the PV up toward setpoint then that is reverse
Example: If a 12 mA output drives a 0 degree F temp. (PV) up to a 1200 degree F temp. (SP) this would be REVERSE and since this would take a SINGLE output from the controller the Mode for the Temperature Loop is Single Reverse.
Integral Preset
This field provides an offset for the starting point for PID control, also referred to as “Load Line” or “Manual Reset”. The range is –100 to 100.
Cycle Time
This field is typically set to the valve travel time multiplied by 1.5.
Setpoint Change Limit
This is a smart time feature that allows Process Loop to use PB only without Reset until the Process Variable drops below the percent output set under this category.
It is used to eliminate overshoot.
The Output percentage selected under this category must be above the normal operating output percentage of the furnace at heat.
Example – if the furnace runs at 40% output at heat for the maximum load, the setpoint change limit should be set to 60%.
Low Limit
This is the low limit field. The range is –100 to 100.
High Limit
This is the high limit field. The range is –100 to 100.
0 Setpoint Stops Control
If the Setpoint is zero, then all outputs are turned off. The option is either Yes or No.
IN1 high limit shuts down ctrl
If input 1’s high limit is reached, then all outputs are turned off. The value can either be Yes or No.
IN2 high limit shuts down ctrl
If input 2’s high limit is reached, then all outputs are turned off. The value can either be Yes or No.
IN3 high limit shuts down ctrl
If input 3’s high limit is reached, then all outputs are turned off. The value can either be Yes or No.
PID Auto Switch
This is the PID auto switch field. The value can either be Yes or No.
Switch Point PID 1 -> 2
This is the PID Switch Point field. The range is –300 to 4000.
Switch Point PID 2 -> 3
This is the PID Switch Point field. The range is –300 to 4000.
Overshoot Limit Gain
This is the Overshoot limit gain field. When calculating the control action sometimes the calculation would call for more than 100% which is not possible. The output is limited to 100%, or whatever was set in the High Limit field. The difference of the unlimited minus the limited is multiplied by the over shoot limit gain and divided by 100. This is subtracted from the control output. If the gain is 0 there is no effect. Under normal control the unlimited equals the limited and there is no effect. If there is a big change where the control loop drives hard, then the effect is to limit the drive as it approaches setpoint and limit the overshoot.
The limited is the values set in the upper and lower limits fields. The unlimited would be what is calculated before limiting. For a big setpoint change, the calculations may compute 150% output, but the true output is limited to the upper limit.
The range is 0 to 9999.
Deviation Setpoint
This will set the deviation alarm setpoint. The range is 0.00 (OFF) to 32000.00.
Dev. Alarm Delay (Seconds)
This will set the delay in seconds before the deviation alarm becomes active. The range is 0 to 32000.
Setpoint Lower Limit
This is the setpoint lower limit for the loop. The range is -9999 to 9999.
Setpoint Upper Limit
This is the setpoint upper limit for the loop. The range is -29999 to 29999.
Factory Default Configuration:
Loop 1 (Kn/Dissoc)
|
LP 1 Prop Band (DB ON/ OFF) |
1.3 |
|
|
LP 1 Reset |
0.01 |
|
|
LP 1 Rate |
0.00 |
|
|
LP 1 Mode |
Dual Direct |
|
|
LP 1 Integral Preset |
0 |
|
|
LP 1 Cycle Time |
24 |
|
|
LP 1 Setpoint Change Limit |
OFF |
|
|
LP 1 Low Limit |
-100 |
|
|
LP 1 High Limit |
100 |
|
|
LP 1 Zero SP stops control |
No |
|
|
LP 1 IN1 High Limit shuts down control |
No |
|
|
LP 1 IN2 High Limit shuts down control |
No |
|
|
LP 1 IN3 High Limit shuts down control |
No |
|
|
LP 1 PID Auto Switch |
No |
|
|
LP 1 Switch Point PID 1 -> 2 |
99.99 |
|
|
LP 1 Switch Point PID 2 -> 3 |
99.99 |
|
|
LP 1 Overshoot Limit Gain |
0 |
|
|
LP 1 Deviation Setpoint |
OFF |
|
|
LP 1 Dev. Alarm delay (seconds) |
0 |
|
|
LP 1 Setpoint Lower Limit |
-99.99 |
|
|
LP 1 Setpoint Upper Limit |
299.99 |
|
Loop 2 (Temperature)
|
LP 2 Prop Band (DB ON/ OFF) |
20.0 |
|
|
LP 2 Reset |
0.10 |
|
|
LP 2 Rate |
0.00 |
|
|
LP 2 Mode |
Single Reverse |
|
|
LP 2 Integral Preset |
0 |
|
|
LP 2 Cycle Time |
60 |
|
|
LP 2 Setpoint Change Limit |
80 % |
|
|
LP 2 Low Limit |
0 |
|
|
LP 2 High Limit |
100 |
|
|
LP 2 Zero SP stops control |
No |
|
|
LP 2 IN1 High Limit shuts down control |
No |
|
|
LP 2 IN2 High Limit shuts down control |
No |
|
|
LP 2 IN3 High Limit shuts down control |
No |
|
|
LP 2 PID Auto Switch |
No |
|
|
LP 2 Switch Point PID 1 -> 2 |
9999 |
|
|
LP 2 Switch Point PID 2 -> 3 |
9999 |
|
|
LP 2 Overshoot Limit Gain |
0 |
|
|
LP 2 Deviation Setpoint |
N/A |
|
|
LP 2 Dev. Alarm delay (seconds) |
N/A |
|
|
LP 2 Setpoint Lower Limit |
-9999 |
|
|
LP 2 Setpoint Upper Limit |
29999 |
|
Loop 3 (Backpressure)
|
LP 3 Prop Band (DB ON/ OFF) |
4.0 |
|
|
LP 3 Reset |
0.10 |
|
|
LP 3 Rate |
0.00 |
|
|
LP 3 Mode |
Single Reverse |
|
|
LP 3 Integral Preset |
0 |
|
|
LP 3 Cycle Time |
60 |
|
|
LP 3 Setpoint Change Limit |
OFF |
|
|
LP 3 Low Limit |
0 |
|
|
LP 3 High Limit |
100 |
|
|
LP 3 Zero SP stops control |
No |
|
|
LP 3 IN1 High Limit shuts down control |
No |
|
|
LP 3 IN2 High Limit shuts down control |
No |
|
|
LP 3 IN3 High Limit shuts down control |
No |
|
|
LP 3 PID Auto Switch |
No |
|
|
LP 3 Switch Point PID 1 -> 2 |
99.99 |
|
|
LP 3 Switch Point PID 2 -> 3 |
99.99 |
|
|
LP 3 Overshoot Limit Gain |
0 |
|
|
LP 3 Deviation Setpoint |
OFF |
|
|
LP 3 Dev. Alarm delay (seconds) |
0 |
|
|
LP 3 Setpoint Lower Limit |
-99.99 |
|
|
LP 3 Setpoint Upper Limit |
299.99 |
|