Lenze MC3000 Series User Manual

Page 69

13435743_EDBM301_v14 .0

FB @ MAX

(MAXIMUM FEEDBACk VALUE)

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

maximum transducer feedback signal (10 VDC or 20 mA) .
NOTE:

If a reverse acting feedback device is being used, FB @ MIN should be set

to the maximum process variable value, and FB @ MAX should be set to
the minimum process variable value .

P GAIN

(PROPORTIONAL GAIN)

This parameter setting represents the speed command output (in % of maximum speed)

that results from each 1% of error (1% of Parameter 75 - FB @ MIN or 76 - FB @ MAX,

whichever is larger) .
Example:

If P GAIN is programmed for 5%, and the error (difference between setpoint

and feedback) is 10%, the speed command output of the Proportional term

is 50% (10 x 5 = 50) of maximum speed .

I GAIN

(INTEGRAL GAIN)

This parameter setting represents the ramp rate of the speed command output (in % of

maximum speed per second) that results from each 1% of error .
Example:

If I GAIN is programmed for 0 .5 seconds, and the error is 5%, the rate of rise

of the speed command output of the Integral term is 2 .5% (0 .5 x 5 = 2 .5) of

maximum speed per second .

D GAIN

(DIFFERENTIAL GAIN)

This parameter setting represents the speed command output (in % of maximum speed)

that results from each 1% per second change in the error .
Example:

If D GAIN is programmed for 5 seconds, and the error is increasing at 2%

per second, the speed command output of the Differential term is 10% (5 x

2 = 10) of maximum speed .

NOTE:

Differential gain is used as a “shock-absorber” to dampen overshoots in fast-

acting systems . However, it can be very sensitive to “noise” on the feedback

signal and to digitizing errors, so it must be used with caution .

PID ACC

(PID ACCEL/DECEL)

This parameter sets the acceleration and deceleration rate of the setpoint reference into

the PID unit . When the setpoint changes, this function will “filter” the input to the PID unit

by ramping the setpoint reference from the previous value to the new value . This will

help prevent overshoots that can occur when the PID control attempts to respond to step

changes in setpoint, resulting in smoother operation . If PID ACC is set to 0 .0 seconds,

it is effectively disabled .

MIN ALRM

(PID MINIMUM ALARM)

This parameter setting represents the value that the feedback signal (in PID mode) or

speed reference signal (in open-loop speed mode) must fall below to activate the MIN/

MAX ALARM output (refer to Parameters 52, 53, and 54) .