The pump is a two-stage centrifugal pump and was powered by a 3 HP, 240 VAC, 60 Hz, 1 Ph motor running at 3450 PRM. It had been in use for 10 years, used to keep water pressurized in tanks, and controlled by a pressure switch. It had over 6000 hours on it, but I still consider it a premature failure. Just before failure, it made a bit of noise, which increased suddenly with a small amount smoke seen before it was shut down.
The pictures below show a roasted motor with giblets. Main course is burnt stator windings, followed by a melted fan blade, and finish with a thoroughly baked run capacitor.
Run capacitor is same brand as motor ... WEG. Start capacitor is a Lorenzetti and tests OK. So, what failed first? Probably not the stator coils. If the insulation on them had failed first, I would have expected to find a small area that was severely burned, maybe with some melted metal, with progressively less scorching further out. Instead, it appears that there was relatively uniform heating with little or no arcing between conductors. My vote is for the fan blade. If the fan blade fails, everything overheats including the coils and capacitors, which toast and die. The fan blade was nylon and force-fitted to the motor shaft. My guess is that it started losing its grip on the shaft which started things heating, including the shaft, which caused more slippage, and so on.
For a motor/pump combo that costs US$1000-2000, would it be asking too much for a decent run capacitor and a metal fan blade that is solidly attached to the shaft? Maybe so. And a thermal fuse ... how much would that have cost? The motor bearings were in good shape, and the pump is fine.
One other gripe is the motor shaft is extended out so that it is also the pump shaft. This saved some money because the manufacturer didn't have to buy a coupler or a frame capable of holding a separate motor and pump. However, it makes the motor unique to the pump. Unless I want to saw the shaft from the motor, buy a coupler and build a frame, I'm stuck buying the same motor to run the pump.
Mike in California