[Hamid]

In an industrial site, one multi speed electromotor which driven with an SFC unit (static frequency converter,PWM-type) failed and maintenance group decided to replace it, they found an oversize electromotor with suitable technical characteristics and replaced old motor.
In an industrial site, one multi speed electromotor which driven with an SFC unit (static frequency converter,PWM-type) failed and maintenance group decided to replace it, they found an oversize electromotor with suitable technical characteristics and replaced old motor. But after short time operation they faced to SFC unit burning which caused their wonder, because there were not any change in mechanical load profile and they expect same last electronic device loading.
How can you explain the reason of new problem?

Topic

[NADER]

I think , if mechanical load profile doesn’t change , no problem will be presented .But , if profile changes , it’s because Pulse Width Modulation(PWM)method is based on flux control( not torque control) motor will absorb more power and SFC has not been sized for such current and will be damaged .

[Author]

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