When starting a 10kV high-voltage motor, the voltage drop is too large – is the motor safe?
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Our factory is new, and it is equipped with a 10KV, 1400KW centrifugal compressor that comes with a soft start device. During the motor testing phase (before the coupling was connected), the voltage dropped to 6KV at startup. It took 13 seconds for the voltage to rise back to 10KV. What are the risks associated with such a large voltage drop during startup? There’s a concern that the motor might get damaged. Now the management wants to conduct tests with the coupling in place, which increases the risks even further. But how can we convince them? I’m seeking advice from fellow sailors.
Voltage reduction startup should be the correct approach; I’m not sure if 13S is appropriate. Please advise, expert
The voltage drop during motor startup in the factory should be kept within 15%. Based on what you’ve described, the voltage drop is too high when the motor starts; check whether the soft-start current limit is set appropriately Is the capacity of the 10kv transformer sufficient? Does the bus meet the current requirements during startup? The starting current is the same under no-load and loaded conditions; it’s just that the starting time is longer when the load is present, and the starting torque must meet the torque requirements of the load.
The start time should be determined based on the actual start time, provided that the current and voltage parameters are within normal ranges.
The voltage drop upon startup is too high, which is unreasonable; it’s necessary to check the system capacity, cable length and current-carrying capacity, as well as the bearings and other components.
Check the reasons for the voltage drop by considering whether the capacity of the power supply transformer is sufficient, whether the cross-sectional area of each bus bar section is adequate, whether the soft start settings are correct, and whether the current after startup remains within acceptable limits. Such a voltage drop is not beneficial for the motor
If the starting voltage drop is too large, the voltage of other electrical loads will also decrease, causing the current to increase; this could lead to other motors or transformers tripping. Isn’t your manager concerned about the impact this might have on production?