Lenze 8200 motec frequency inverter 0.25kW-7.5kW - Manual (Page 122)

Function library
Process controller, current limitation controller
7−51
L
EDB82MV752 EN 5.2
Pressure control and flow control
·
The differential component K
D
(C0072) is generally not required for pressure and flow control.
·
Set the influence (C0074) to 100 %.
·
Deactivate the frequency feedforward control (C0238 = 0).
Code Setting for
Gases Fluids
C0070 (K
P
) 0.1 0.02 ... 0.1
C0071 (T
N
) 5000 (T
N
= 5 s) 200 ... 1000 (T
N
= 0.2 s ... 1 s)
C0072 (K
D
) 0 0
Speed control
Code Setting
C0070 (K
P
) 5
C0071 (T
N
) 100 (T
N
= 0.1 s)
C0072 (K
D
) 0
Setting of process controller influence
·
Activate frequency feedforward control (C0238 = 1). Now the process controller has only
limited influence:
– The control factor determines the influence of the process controller (C0074).
– Control factor = C0050 (output frequency) − C0051 (actual process controller value)
·
C0074 refers to the maximum output frequency C0011.
·
C0074 influences the stability of the control loop:
– Set C0074 as low as possible.
– If C0074 is set too high, the control loop can become unstable.
Calculation of process controller influence
Calculate C0074 Example
C0074 [%] + C0050 * C0051
C0011
@ 100 %
C0011 = 50 Hz, C0050 = 53 Hz, C0051 = 50 Hz:
C0074 [%] + 53 Hz * 50 Hz
50 Hz
@ 100 % + 6 %
Set the influence so that the process controller output covers the calculated value in every working
point.
Set C0074 = 10 % as guide value for the example (C0074 = 6 %). The guide value contains
tolerances which must always be observed.
Example of additive influence
The effective direction of the process controller output to the main setpoint is additive.
Settings
·
C0051 = positive actual value
·
C0181 = select positive setpoint
·
C0238 = 1 (with frequency feedforward control)
·
Potentiometer terminals of the dancer
– End (E) = +10 V
– Start (A) = GND