Lenze 8240 HVAC Series - Manual (Page 49)

Commissioning
5-9 UOOuhäáã~_^NMMO
3.Set the Vmin boost (C016).
D
Load independent boost of the motor voltage for field frequencies below the rated V/f
frequency.You can thus optimize the torque performance of the inverter drive.
D
It is absolutely necessary to adapt the asynchronous motor used, since otherwise, the motor can
be destroyed by overtemperatue:
Adjustment
Please note the thermal characteristic of the connected motor under small field frequencies:
D
Usually, standard asynchronous motors with insulation class B can be operated for a short time
with rated current and frequencies between 0Hz ≤ f
d
≤25Hz.
D
Please ask the motor manufacturer for the exact setting values for the motor current.
A Operate the motor when no load is applied with a slip frequency of f
d
≈:
- P
Mot
≤7,5 kW: f
d
≈5 Hz
- P
Mot
>7,5 kW: f
d
≈2 Hz
B Increase V
min
until you reach the following motor current:
- Motor in short-term operation at 0Hz ≤f
d
≤ 25Hz:
with self-ventilated motors: I
motor
≤ 0.8 I rated motor
with forced ventilated motors: I
motor
≤ I
rated motor
- Motor in permanent operation at 0Hz ≤f
d
≤ 25Hz:
with self-ventilated motors I
motor
≤ 0.8 ¡ I
rated motor
with forced ventilated motors: I
motor
≤ I
rated motor
4.Set slip compensation Rough setting by means of the motor data: p p
(C021).
л =
е
клуе − е к
е
клуе
⋅ NMMB
е
клуе =
С
Зк
⋅ SM
é
s Slip constant (C021)
n
rsyn
synchronous motor speed [min -1 ]
n
r
rated speed to motor nameplate [min -1 ]
f
dr
rated frequency to motor nameplate [Hz]
p Number of pole pairs
Precise setting:
Change C021 under constant load until the speed is near the synchronous speed.
If C021 is set to too high values, the drive may become instable (overcompensation).
Important The change from V/f-characteristic control to motor-current control should only be made when the
controller is inhibited.
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