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Swimming pool 3 phase motor trips occasionally on earth leakage RCD

We have a new 4 kW 3 phase pump motor at the local pool which has a new variable speed drive unit attached and occasionally it trips out on the RCD which I assume is 30mAmp . The connections are star inside the motor but not earthed which should have stopped it tripping.

We are not sure what to do, we could run the motor flat out and delta connect the windings possibly or some suggest disconnecting the RCD as the circuit is completely separate from normal wiring. Would this option contravene any of our regs?

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0 CliveS over 4 years ago

Thanks Chris and Mike

My memory says motor efficiency is dependant on the iron and copper losses. Now if we run at full load then whether the supply is direct from grid or via a VSD those losses cannot be avoided.

That means that the 10% extra loss of the VSD make it much less efficient overall and an amendment should be floated to the EU to exempt such machines. Added bonus is it lowers the original cost and eliminates electronic flutter and unreliability.
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0 CliveS over 4 years ago

Thanks Chris and Mike

My memory says motor efficiency is dependant on the iron and copper losses. Now if we run at full load then whether the supply is direct from grid or via a VSD those losses cannot be avoided.

That means that the 10% extra loss of the VSD make it much less efficient overall and an amendment should be floated to the EU to exempt such machines. Added bonus is it lowers the original cost and eliminates electronic flutter and unreliability.
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Swimming pool 3 phase motor trips occasionally on earth leakage RCD

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