G120X commissioning guide for permanent magnet motors PMSM
Entry-ID: 109780815, V1.0, 07/2020
Sometimes the motor manufacturers provide the nominal voltage of the supply grid the inverter
is connected to rather than actual motor rated voltage. If the motor nameplate shows nominal
mains voltage like 380V, 400V, 480V etc. then in most cases you can calculate correct value
provided other nameplate data is consistent:
Some other PMSM motor manufacturers provide nameplate data containing PWM content –
i.e. actual values measured at the end of temperature rise tests with motors supplied from a
reference inverter. This could cause issues during commissioning as this data differs from the
required fundamental (1
st
harmonics) values normally used in motor model. Commonly it
shows rated voltage higher and power factor smaller. Using this data may lead to nuisance
overcurrent or ground faults during commissioning. See chapter 3.3.2 Troubleshooting how to
deal with this issue.
Some incomplete motor nameplate data can be calculated using following equations:
Motor rated power:
P
n
=M
n
* 2 * π * N
n
/60 [W]
M
n
– rated torque [Nm]
N
n
- rated speed [rpm]
Approximate motor rated voltage (if efficiency and power factor unknown):
f
n
– motor rated frequency [Hz]
I
n
– motor rated current [A]
Lq – motor quadrature inductance phase-starpoint [H]
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