Page 71 - 1SBC104119C0202_MainCatalog_R contactors

Autotransformer starters

General Electrical distribution KM2
An autotransformer starter allows to start a squirel cage motor
with a reduced starting current due to the reduced voltage KM1
within the accelerating duration.
At the contrary of the star-delta wiring, this autotransformer T1 5
starting method needs three wires and three terminals on the
motor. Autotransformer
At the starting period, the motor is wired to the auto-
transformer taps: the "KM3" star contactor and the "KM2" KM3
autotransformer contactor are closed, the motor is under
reduced voltage. Consequently, the torque is reduced as
the square of the applied voltage. The autotransformers are
generally equipped of three taps at each phase in order to
adapt the starting parameters to the field requirements.
When the motor reaches 80...95% of its nominal speed,
the star contactor opens. Then, the "KM1" line contactor is
making and the autotransformer contactor is opening. This
starting process is done without any network interruption.

Selection table (Id starting current / In nominal current < 8 - Acceleration time < 20 s - 30 cycles / h max.)

Motor ratings Contactors

50/60 Hz KM1 KM2 KM3

440 V Line Autotransformer taps Autotransformer taps

kW 90 % 80 % 70 % 60 % 90 % 80 % 60-70 %
IOR..500..MT
500 IOR..800 IOR..800 IOR..500..MT IOR..400..MT IOR..400..MT IOR..200..MT IOR..400..MT IOR..500..MT
IOR..800
560 IOR..1400 IOR..800 IOR..500..MT IOR..500..MT IOR..400..MT IOR..200..MT IOR..400..MT IOR..800
IOR..800
630 IOR..1400 IOR..800 IOR..800 IOR..500..MT IOR..400..MT IOR..200..MT IOR..400..MT IOR..1400
IOR..1400
710 IOR..1400 IOR..1400 IOR..800 IOR..500..MT IOR..400..MT IOR..200..MT IOR..500..MT

800 IOR..1700 IOR..1400 IOR..800 IOR..800 IOR..500..MT IOR..400..MT IOR..500..MT

900 IOR..2100 IOR..1700 IOR..1400..MT IOR..800 IOR..500..MT IOR..400..MT IOR..800

1000 IOR..2100 IOR..1700 IOR..1400..MT IOR..800 IOR..500..MT IOR..400..MT IOR..800

1SBC104077S0201

ABB R contactors | 5/19