Torsional Loading Of The Drive Train Due To Faults In The Electrical Supply; Switching High-Voltage Motors; Table 4-1 Power Limits - Siemens SIMOTICS HV C Operating And Installation Instructions

Induction motor

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4.9

Torsional loading of the drive train due to faults in the electrical supply

In the event of faults in the electrical connection, such as line switching operations with a

residual field or short circuit at the terminals, excessive air gap torques can occur. These

excessive air gap torques can lead to additional mechanical torsional loads on the shaft

assembly.

If the configuration does not correctly recognize the mechanical torsional loadings of the shaft

assembly, this can lead to serious damage to the machine. This can result in death, serious

injury or material damage.

● When planning the system, make due allowance for the maximum air gap torques that can

The system planner is responsible for the entire drive train.

4.10

If vacuum circuit breakers and vacuum contactors are used, then what are known as multiple

restrikes can occur when the machine is switched off. This depends on various factors, such

as:

● Arc-extinguishing principle of the switch

● Machine size

● Length of the power supply cable

● System capacitance, etc.

A surge suppressor to ground is installed in the switchgear between the circuit breaker and

the cable termination for each of the three conductors. The level of protection for the machine

windings is sufficient when the limiter is correctly selected (machine rated voltage / response

voltage).

Example

This current limit corresponds to the following upper power limits, depending on the relationship

between the starting current I

20%) while the machine is starting up:

Table 4-1

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