480 volt 50 hp motor overload tripping

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FREEBALL

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york pa usa
I have a 50 amp 480 volt baldor induction motor/pump fed thru a soft start controller all is brand new. The motor feeds water to a spinner system for tank washing. The motor will start and gain speed then will slow down and then gain speed and then slow down and then gain speed and then trip at 240 amps on a 100 amp breaker. The soft start does not activate. We thought it was alignment of pump and shaft causing friction but it is unknown until pump person comes out, Anybody have any familiarity to this issue.

There is another system set up beside this system same motor size on separate soft start in the same control panel, which works fine. I replaced the leads to this soft start and the same thing so I don't think it is in the soft start but in the motor or piping.

Thanx in advance
jeff
 
delta

delta

ActionDave said:
Is it an electronic soft start or a wye start delta run?
Click to expand...

Well I believe delta delta im not a motor man but all the motors in the building have been delta all have worked but this particular motor.

l1 to 1 l2 to 2 l3 to 3 4-7 5-8 6-9 does this help
 
Last edited:
FREEBALL said:
Well I believe delta delta im not a motor man but all the motors in the building have been delta all have worked but this particular motor.

l1 to 1 l2 to 2 l3 to 3 4-7 5-8 6-9 does this help
Click to expand...

That means the motors leads are wired up for 480V. I'm asking about the soft starter. There are two kinds of soft starts...

An actual soft start that reduces the voltage to the motor when starting

A wye start delta run starter that uses two contactors to physically switches the power to the motor leads.

I'm taking a stab in the dark, but it sounds like you have a wye start delta run problem
 
Motor is wired standard high voltage (480V) Wye. Many soft starts have a bypass contactor that bypasses the soft start after reaching full speed. That means the overload is independent of the soft start SCR's after the motor is up to speed. The speeding up and slowing down sounds like an "up to speed" sensor may be malfunctioning.
 
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You said the soft start never activated. How did the motor start, then? Not sure what that means. Is there a way to de-couple the pump and run the soft start on the motor alone? If the controllers are located close together, maybe you could run temporary jumpers from a known good starter to the "bad" motor/pump to see if the problem goes away. That would eliminate questions about the motor/pump.
 
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