I have a customer that has a 3ph 5 hp commercial pool pump. They say it does not last longer than 6 mos. I checked voltage. It's a 208 system. The voltage at source is 204 to 203 a little VD. It is a long run but voltage is with in 3% to 5%. Any ideas? It has has motors heater for protection.:-?
Do you know what is going bad on the motors? Windings, bearings, etc?
If it's the windings, do they get them examined by a competent motor shop to see what kind of damage it is? There are ways for them to tell what type of event caused the failure by how the damage looks and tests out.
Do they have any current imbalance?
Did someone crank up the OL dial because they got tired of resetting it?
If so, is it because the motor too small, or did they change the flow so that even if it was sized right in the beginning, it isn't now?
Are the motors exposed to the pool chemicals? Acid and Chlorine are really nasty on motors and I have seen a number of places where they store the chemicals in the equipment room. Of course they are not supposed to spill the chemicals in the room, but Joe-Bob the pool guy won't rat himself out if he does, so when asked he always saws "No!"
Even though they have winding heaters, does Joe-Bob realize that when he flips all the breakers off at night, he's killing power to the heaters too? (See that one a lot).
Lots more possibilities on this.