Advanced Operations

6.3.3.7 Function set to PWM CONTROL/PID CONTROL working mode

PWM CONTROL/PID CONTROL

 

SET FUNCTION

Default value: LINEAR

 

The 2nd SET FUNCTION menu sets the PWM signal status.

 

 

 

 

 

 

 

 

 

LINEAR

Signal is linearly dependent on the process value.

 

 

 

 

 

 

PID CONTROL

Signal works as a PID controller.

 

 

 

 

 

 

 

Default value: 0%

 

SET TRANSFER

Sets a substitute PWM ratio when some error conditions are detected in the selected source or if

 

 

 

the source is missing.

 

 

 

 

SET MODE

Default value: AUTOMATIC

 

 

 

 

 

 

AUTOMATIC

The relay output works as a PID controller.

 

 

 

 

 

 

MANUAL

The relay output has got an on/off ratio as set in the menu MANUAL OUTPUT.

 

 

 

 

 

MANUAL OUTPUT

Indicates the current on/off ratio.

 

Additionally the on/off ratio can be set (condition: SET MODE is set to MANUAL). Note that this

 

(0%100%)

 

ratio cannot exceed a value beyond the values set in the MINIMUM and MAXIMUM menus.

 

 

 

 

 

 

 

 

PHASE

Default value: DIRECT

 

Reverses the leading sign of the control deviation for the PID controller.

 

 

 

 

 

 

 

MINIMUM

Default value: 0%

 

(0%100%)

Sets the minimum PWM ratio.

 

 

 

 

MAXIMUM

Default value: 100%

 

(0%100%)

Sets the maximum PWM.

 

 

 

 

 

SET POINT

Default value: 10

 

Sets the process value which is controlled by the PID controller.

 

 

 

 

 

 

 

 

 

 

Default value: 1

 

DEAD ZONE

The dead zone is a band around the set point. In this band the PID controller does not change

 

the PWM on/off ratio output signal. This band is determined as set point +/- dead zone. The

 

 

 

 

 

 

dead zone stabilizes the PID controlled system which have a tendency to oscillate.

 

 

 

 

 

PERIOD (0600 s)

Default value: 5 seconds

 

Sets the cycle duration of the PWM output signal.

 

 

 

 

 

 

 

 

 

 

Default value: 1

 

 

 

Sets the proportional part of the PID controller.

 

PROPORTIONAL

The proportional part of the controller generates an output signal which is linearly dependent to

 

the control deviation. The proportional part reacts on any changes at the input but starts to

 

 

 

 

 

 

oscillate easily if the value is set high. The proportional part cannot completely compensate

 

 

 

disturbances.

 

 

 

 

 

 

 

Default value: 15 minutes

 

 

 

Sets the integration part of the PID controller.

 

INTEGRAL

The integration part of the controller generates an output signal. The output signal increases

 

linearly if the control deviation is constant. The integration part responds slower than the

 

 

 

 

 

 

proportional part and can completely compensate disturbances. The higher the integration part,

 

 

 

the slower it responds. If the integration part is set to low, it starts to oscillate.

 

 

 

 

 

 

 

Default value: 5 minutes

 

 

 

Sets the derivative part of the PID controller.

 

 

 

The derivative part of the PID controller generates an output signal which depends on the control

 

 

 

deviation changes. The faster the control deviation changes, the higher the output signal gets.

 

DERIVATIVE

The derivative part creates an output signal as long as the control deviation changes. If the

 

control deviation is constant, no signal is created.

 

 

 

 

 

 

The derivative part is able to smoothen the oscillation caused by the proportional part. The

 

 

 

derivative part allows the proportional part to be set higher and the controller responds faster.

 

 

 

If there is no knowledge about the controlled process behavior, it is recommended to set this part

 

 

 

to “0”, because this part tends to oscillate strongly.

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Hach sc1000 user manual Function set to PWM CONTROL/PID Control working mode, 102