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Motor insulation fault detection method by ground leakage current detection
Motor insulation fault detection method by ground leakage current detection
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机译:漏电电流检测电机绝缘故障的方法
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摘要
Motor insulation degradation is determined using circuitry to sense the common mode leakage current from the ground wire cable. In a preferred embodiment of the invention, a small current transformer detects the common mode leakage current flowing in the ground wire cable of the motor controller circuit. A single pole low pass filter generates an average leakage current signal from the sensed current. The average leakage current signal is converted to a PWM signal. A pulse generator receives the PWM signal and generates pulse signals at the rising and falling edges of the PWM signal. A pair of level shifters receive the rising edge and falling edge pulse signals and transpose those signals from a floating high voltage to a voltage referenced to ground. A pulse reconstruction circuit receives the level shifted pulse signals and reconstructs a pulse width modulated signal having a duty cycle which varies with respect to the magnitude of the common mode leakage current. This output signal is input directly to a microcontroller or a digital signal processor to calculate and determine the amount of motor insulation degradation.
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