High efficiency motor and soft starter problem 1

[tlona]

We have a fuel oil pumping system consisting of two centrifugal pumps each driven by 100HP motor. Both mother feeders are identical each with the exact same soft starter. One of the motors had to be replaced. The replacement motor is a high efficiency motor and now keeps tripping the soft starter. We swap circuits, motors, starters, etc and whatever configuration connects to the new motor, the starter trips. We changed to a different soft starter and still trips. Wires and motor meggered and all pass. Motor bench tests satisfactory. Has anyone had any issues using soft starters with high efficiency motors?

 

[tlona]

Yes. We had two WEG starters (100HP and a 150HP). Both tripped uncoupled motors (38 running amps) after starting with an E04 error code. The WEG rep on site could not believe it and really had no answer other than they were defective. I asked if they had issues with high efficiency motors but they claimed they did not. My thinking is that initial asymetric inrush that you cant see with a clamp on maybe is enough to overheat it.