Must the power for the control circuit of the submersible sewage pump be supplied from the upper side of the circuit breaker in that main circuit?
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Hello, experts. I’m at a wastewater site, where I’m using a 15KW submersible sewage pump (its insulation has been tested and is fine). However, it trips as soon as power is applied when I try to put it into operation. The main circuit of this device is equipped with a Delta residual current circuit breaker, the NM1LE100S (with a fixed current setting of 30mA); it trips as soon as power is supplied, and the reason for this cannot be determined. Later, a colleague changed the power supply for the control circuit of that device from the lower end of the main circuit breaker to an appropriate location, allowing normal power supply and operation once the power was turned on. I have a question: 1. Does the main circuit breaker of the submersible sewage pump need to be equipped with a residual current device? 2. Why is it sufficient to change the power supply for the control circuit from the lower end to the upper end of the main circuit breaker? Is the leakage current less than 30 mA? Is this accidental or due to technical reasons? Could you please help analyze it?
I would also appreciate it if the experts could help answer this question. Thank you.
Your control circuit operates at 220V; the leakage protector is connected to only one phase wire, and the neutral wire does not pass through the leakage protector during operation, which leads to incorrect detections by the leakage protector.