Pid loop setup – Super Systems 9205 Series User Manual

Page 29

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Series 9205 Operations Manual Rev A

28

Digital IN 4 Assignment: The value for the digital input 4 assignment. Clicking on the value will allow the

user to change the value, which can be either event or Start Burnoff.

Burnoff Minimum Millivolts Alarm Setpoint: The minimum millivolt value that must be reached in order for

the “Insufficient mV drop during BO” alarm not to be generated. If the millivolt value does not drop below

the minimum, the alarm will be generated.

Burnoff Maximum Temperature Rise Limit: The maximum number of degrees that the temperature is

allowed to increase before the “Excessive TC rise during BO” alarm is generated.

PID Loop Setup

PID is the tuning parameters entered for each Process

Variable loop.

Prop Band (0 for On/Off)

Proportional Band determines the response to the

current error. The Proportional Band is the percent of

the range of the process variable that will produce

100% output and is the inverse of the proportional gain.

A low Proportional Band value results in a larger

change in output for a given error. Conversely, a high

Proportional Band value results in a smaller change in

output for a given error. If the Proportional Band is too

small, control may oscillate or be otherwise unstable.

If the Proportional Band is too large the control action may be too sluggish in response to changes within

the system. Note: If the Proportional Band is set to 0.0, only on/off control is performed. The range 0 –

3276.0.

Reset

Reset determines the influence of past errors. The Reset, or integral action (expressed in repeats per

minute), sums the error between the process variable and setpoint over time and adds this accumulated

output to the proportional output. A “proportional only” controller generally operates with steady-state

error because some error is required to produce control output. The goal of integral action is to drive the

steady-state error to zero and eliminate this droop.

The range 0 – 327.67.

Rate

Rate adjusts the response to future errors.

The Rate, or derivative action (expressed in minutes), is used to

predict system behavior and has a dampening effect. The more the controller tries to change the process

variable the harder the derivative will work to counter that effort. This dampening effect can be valuable in

reducing overshoot but is most often useful when trying to improve control on systems with significant and

predicable lag.

The range 0 – 327.67. NOTE: The rate is not typically used for carbon control.

Control 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 the SP.

Single – This has one relay which works in only one direction to achieve the 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

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