Lenze 8200 Frequency inverters - Manual (Page 116)

Commissioning
8200SHB0199 5-11
3.Set V
min
boost (C016). Load-dependent boost of the motor voltage in the field frequency range below the V/f-rated
frequency. C016 acts as gain factor of the auto-boost function.
Adjustment
In general, an adjustment is not necessary. An optimisation can be advantageous:
For drives with very high starting torques:
A Operate the motor under load.
B Select the frequency setpoint.
C Increase V
min
until the required motor current (torque) occurs.
If the setting of V
min
is too high, a positive-feedback effect can occur and activate the TRIP
”overcurrent” (OCx).
For drives with square load torques (fans, pumps):
A Operate the motor under load.
B Select the frequency setpoint.
C Adapt V
min
until the motor is running steadily and smoothly over the whole frequency range.
If the setting of V
min
is too high, the TRIP ”overcurrent” (OCx) can be activated and lead to an
excessive motor temperature.
For drives with special motors:
A Operate the motor under load.
B Select the frequency setpoint.
C Increase V
min
until the required motor current (torque) occurs.
If the setting of V
min
is too high, a positive-feedback effect can occur and activate the TRIP
”overcurrent” (OCx).
D Check the current consumption during idle running when no load is applied.
4.Set the slip compensation
(C021).
Rough setting according to motor data: 4.Set the slip compensation
(C021).
s
n
Nsyn
Å n
r
n
Nsyn
ô 100 %
n
Nsyn
f
dr
ô 60
p
s Slip constant (C021)
n
Nsyn
Synchronous motor speed [min -1 ]
n
r
Rated speed to motor nameplate [min -1 ]
f
dr
Rated frequency to motor nameplate [Hz]
p No. of pole pairs (1, 2, 3, ...)
Precise setting:
- Correct C021 until no load-dependent speed drop occurs in the required speed range between
idle running and max. motor load.
- If the values under C021 are too high, the drive may become instable (overcompensation).
- In the field frequency range between 5 Hz ... 50 Hz (87 Hz) the deviation of the rated speed is
$ 1 %(guide value). In field-weakening operation, the fault increases.
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