Lenze MC3000 Series - Manual (Page 69)

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76 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 .
77 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 .
78 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 .
79 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 .
80 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 .
81 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) .