Overvoltages When Switching High-Voltage Motors - Siemens SIMOTICS HV C Operating And Installation Instructions

3. If it runs perfectly, connect a load.
4. During the test run, check and document the following:
5. In case of uneven running or abnormal noise, switch off the machine. As the machine runs
7.5

Overvoltages when switching high-voltage motors

When commissioning high-voltage motors or switchgear for high voltage motors from 3 kV and
above, surge voltages can occur while starting. This can damage the machine.
SIMOTICS HV C 1NB1402-2AA84-4CA0-Z
Operating Instructions 06/2018
NOTICE
Thermal overload of motors connected directly to the line supply
In addition to the load torque, the ramp-up (accelerating) time is essentially influenced by
the moment of inertia to be accelerated. While ramping up when connected to the line
supply, the inrush (starting) current is a multiple of the rated current. This can result in
thermal overload. This can damage the motor.
As a consequence, when ramping up, observe the following:
● Monitor the ramp-up time and number of consecutive starts.
● Comply with the limit values and/or ramp-up conditions specified in the catalog or the
order documentation.
– Check whether it is running smoothly.
– Document the voltage, current and power values. As far as possible, document the
corresponding values of the driven machine.
– If this is possible using the available measuring equipment, check the bearing and stator
winding temperatures until they have reached steady-state values.
– Check the machine for noise or vibrations on the bearings or bearing shields as it runs.
down, identify the cause.
– If the mechanical operation improves immediately after the machine is switched off, then
the cause is magnetic or electrical.
– If the mechanical running does not improve immediately after switching the machine off,
then the cause is mechanical.
- Imbalance of the electrical machine or the driven machine
- The machine set has not been adequately aligned
- The machine is being operated at the system resonance point. System = motor, base
frame, foundation, ...
NOTICE
Serious damage to the machine
If the vibration values in operation are not maintained in accordance with
DIN ISO 10816-3, then the machine can be mechanically destroyed.
● During operation, observe the vibration values in accordance with DIN ISO 10816‑3.
7.5 Overvoltages when switching high-voltage motors
Commissioning
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