Siemens SINAMICS G120, Installation Manual

Page: 67 / 176

Connecting
4.4 Connecting the motor to the converter in a star or delta connection
Power Module PM240-2
Hardware Installation Manual, 01/2020, A5E33294624B AL
65
Operating the motor in a delta connection with 87 Hz characteristic
In a delta connection, the motor is oper-
ated with a voltage and frequency above
its rated values. As a consequence, the
motor power is increased by a factor
√ 3 ≈ 1.73.
In the range f = 0 … 87 Hz, the motor
can output its rated torque M
N
.
The maximum voltage U = 400 V is
available at a frequency of
f = √ 3 × 50 Hz ≈ 87 Hz.
The motor only goes into field weakening above 87 Hz.
The higher motor power when operated with an 87 Hz characteristic has the following
disadvantages:
● The converter must supply approximately 1.73x current. Select a converter based on its
rated current - and not its rated power.
● The motor temperature increases more significantly than when operated with f ≤ 50 Hz.
● The motor must have windings that are approved for a voltage > rated voltage U
N
.
● As the fan impeller rotates faster, the motor has a higher noise level than operation with
f ≤ 50 Hz.