LB
II
-PLUS Technical Manual
22
Figure
Winding wiring diagram
Figure
Direct start wiring diagram
Suggestions:
1.
Switching time for winding start
:
0.5s
2.
It is suggested that the selection of the motor contactor (k1/k2) requires the respective rated current
to be equal to about 60% of the maximum operating current.
3.
The starting feature of the partial winding: the starting current is 40% ~ 70% of the total locked rotor
current of the winding, and the starting torque is high.
2.4.2
Power requirements
Power restriction
Voltage restriction: Long time operation: Rated voltage ±5%
Instantaneous operation: Rated voltage ±10%
Frequency: Rated frequency ±2%
Three-phase voltage unbalance
The unbalanced three-phase voltage is mainly caused by unequal distribution of three-phase load.
NEMA (The Association of Electrical Equipment and Medical Imaging Manufacturers) defines voltage
unbalance and current unbalance as below:
The unbalance current will change within the range of 6~10 times of the percentage of voltage unbalance. Over
current will cause overheating of the winding, which will shorten the life of the compressor, and even destroy the
motor. If the unbalanced voltage is large, the torque will be reduced and the operating requirements cannot be met,
so the motor will not be able to get the required rotation speed.
PW1 PW2
PW1 PW2
L3
L1
L2
L1
L2
L3
L1
L1
L2
L3