Lenze MCH Series User Manual

Page 72

13435744_EDBMH01_v13

PID MODE

This parameter activates the PID function, and selects whether the PID control will be

direct or reverse acting. Refer to Section 19.0 - MCH PID SETPOINT CONTROL. The

following options are available:
OFF

Disables the PID function to allow “standard” drive operation.

NORMAL

Enables the PID function for direct-acting systems. An increase in the

feedback variable will cause a decrease in motor speed.

REVERSE

Enables the PID function for reverse-acting systems. An increase in

the feedback variable will cause an increase in motor speed.

NOTE:

The REVERSE selection is not used to compensate for reverse acting

feedback devices. If a reverse acting feedback device is used, program

Parameters 75 and 76 - FEEDBACK @ MIN and FEEDBACK @ MAX as

described in Section 19.1 - FEEDBACK DEVICES.

When PID is enabled, and the drive is in AUTO mode, the drive will operate in a

CLOSED LOOP fashion, responding to the feedback signal in order to maintain the

process setpoint. In this case, the PID setpoint reference is controlled by the source

defined by AUTO SOURCE (Parameter 24). The SPEED REFERENCE SOURCE

indication in the CONTROL display will indicate AKB (keypad), VDC (0-10 VDC) or IDC

(4-20 mA) depending on the setpoint reference source.
When PID is enabled, and the drive is in HAND mode, the drive will operate in an OPEN

LOOP fashion, responding directly to speed commands from the keypad or Preset #3,

depending on the setting of HAND SOURCE (Parameter 29). In this configuration, the

other settings in HAND SOURCE are disabled, and speed control will default to the

keypad.
When PID is disabled, the drive will operate in an OPEN LOOP fashion, responding

directly to speed commands from the selected speed reference source (HAND

SOURCE or AUTO SOURCE).
74

PID FEEDBACK

This parameter selects the terminal to be used for the feedback signal, and can be set

to TB-5A or TB-5B. TB-5A is used for 0-10 VDC signals, and TB-5B is used for 4-20

mA signals.
NOTE:

The MCH has only one analog input of each type, so the same type of

signal cannot be used for feedback and setpoint reference. For example, a

4-20 mA signal from a transducer could not be used as a feedback signal

if the setpoint is being controlled by a 4-20 mA signal from a PLC.

FEEDBACK @ MIN

This parameter should be set to the value of the process variable that

corresponds to the minimum transducer feedback signal (0 VDC or 4 mA).