How to protect against frequent breakdown of soft starters at a water pumping station?

[SA07]

Hi
We have a pumping station with the following pumps supplied by soft starters. We noticed frequent breakdown of soft starters. The station is supplied by the utility grid 22 kV through a 22kV/400 V transformer. There are frequent faults on this 22 kV and we have no control on it. It seems sometimes we have 1 phase missing due to fuse blown off.
What protection equipment can we install to protect our soft starters?

pump borehole 110 kW : soft starter
pump 110 kW : soft starter
pump borehole 45 kW: star delta
pump 75 kW : star delta

 

[LionelHutz]

Give details on the soft-starter failures?

FYI, any good soft-starter will protect against a phase loss or phase unbalance without extra external equipment.