Pid Application Examples - Zener MSC-3 Instruction Manual

4. PID Tuning Summary:
Problem
In closed loop the PV does not
match the desired operating point
In closed loop operation the system
is unstable
The system responds too slowly
The system oscillates momentarily
PV does not equal the SV

PID Application Examples

Step by Step procedures for the following applications are shown in the application sections of this
manual
Application: Stair pressurisation fan with internal PID
Refer to page 38 of this manual for this application. This setup is for a typical HVAC stair
pressurisation fan application that requires air pressure control using an air pressure transducer and PID
controller function provided by the MSC-3. The MSC-3 is configured to run in essential services override
(ESO) mode. Prior to commissioning, you will need to know the type of air pressure transducer signal
that is to be used (0-10V, 4-20mA).
Application: Cooling tower fan with reverse acting internal PID
Refer to page 41 of this manual for this application. This setup is for a typical cooling tower fan
application that requires water temperature control using a water temperature transducer and the PID
controller function provided by the MSC-3. Prior to commissioning, you will need to know the type of air
pressure transducer signal that is to be used (0-10V, 4-20mA).
Application: Water pumping with automatic pressure control
Refer to page 24 of this manual for this application. This setup is for a typical centrifugal pump
application that requires water pressure control using a water pressure transducer and the PID controller
function provided by the MSC-3. Prior to commissioning, you will need to know the type of air pressure
transducer signal that is to be used (0-10V, 4-20mA).
Remedy
• Check the analogue input reading matches the transducer
output signal;
• Verify the settings of the selected analogue input for the
PV;
• Check the running mode reference (Remote, Local, ESO,
JOGFWD or JOGREV) is set to > PID Output.
Increase the H01 PB (%) or decrease H03 Td (sec).
Decrease the H01 PB (%) or decrease the H02 Ti (sec/r).
Increase the H01 PB (%) or decrease the H03 Td (sec).
A steady state error exists and is removed by using the H02
Ti (sec/r). Start with a large value and then decrease it until a
satisfactory response to a SV change is observed.
IM00120 IM00120
MSC-3 Instruction Manual
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