Bad Overloads?

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jerjwillelec

Senior Member
Location
Nevada, IA
I have a 12 year old three phase motor for a water pump at a local swimming pool. The nameplate is pretty corroded but I can read at 230 volts it pulls 51.3 amp so I'm guessing it to be about a 20 HP motor. There are two exact motors side by side pumping water into the same line to a slide. One of the motors has recently started tripping the overloads on the contactor. It will run just fine for 3 to 6 minutes and then the overlods trip. Both motors are pulling the same load within an amp or so. I turned the solid state overload setting up to 80 (as a test) and it still trips though it maxes out at 56 amp while it's running. I've never seen solid state overloads 'go bad' but I guess anything is possible. Any thoughts?
 

PEDRO ESCOVILLA

Senior Member
Location
south texas
might be brushes in the motor. check that and all connections. you can replace the overloads, if that keep giving out, amp clamp the motor brach circuit conductors behind the overloads to see whats up
 

zog

Senior Member
Location
Charlotte, NC
Chemicals used in pools are very corrosive and can damage the internals of a solid state trip unit, is this breaker in a room where they store the chemicals?
 

kwired

Electron manager
Location
NE Nebraska
I have a 12 year old three phase motor for a water pump at a local swimming pool. The nameplate is pretty corroded but I can read at 230 volts it pulls 51.3 amp so I'm guessing it to be about a 20 HP motor. There are two exact motors side by side pumping water into the same line to a slide. One of the motors has recently started tripping the overloads on the contactor. It will run just fine for 3 to 6 minutes and then the overlods trip. Both motors are pulling the same load within an amp or so. I turned the solid state overload setting up to 80 (as a test) and it still trips though it maxes out at 56 amp while it's running. I've never seen solid state overloads 'go bad' but I guess anything is possible. Any thoughts?

What brand is the SSOLR? Out here where there is lots of irrigation pump motors located in both wet and condensing environments the Siemens (and previous versions with Furnas name) seem to be the worst at failing like this.

What you described is exactly what they do. I once took one apart and experimented with it a little. After I got it dried out it seemed to work - but it got replaced anyway.

I have opened enclosures and seen water standing on top of the SSOLR in a few cases, and am pretty certain this is what gets them. Square D pump panels are the other popular choice around here. Only issues I ever have with them is usually when physical damage or lightning events have occured.
 
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