MSC-3 Instruction Manual
4. PID Tuning Summary:
Problem Remedy
In closed loop the PV does not
match the desired operating point
• 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.
In closed loop operation the system
is unstable
Increase the H01 PB (%) or decrease H03 Td (sec).
The system responds too slowly Decrease the H01 PB (%) or decrease the H02 Ti (sec/r).
The system oscillates momentarily Increase the H01 PB (%) or decrease the H03 Td (sec).
PV does not equal the SV 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.
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 congured 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).
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