electric motor tripping breaker

Old 05-20-02, 06:34 AM
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Question electric motor tripping breaker

I have a 7.5HP, Baldor 230V, 35A, 1725RPM, electric motor that runs an air blower. It runs for 24 straight hours once every 3 days. It has begun tripping the breaker after years of reliable service. The breaker is a 70A Square D. Sometimes it'll run for an hour or so before tripping the breaker, other times it'll run for only a few minutes. I'm thinking that the motor is worn out and needs rewound. Does this sound right? What else could be wrong? Like I say, this motor has been reliable for at least 10 to 15 years. Thanks.
Old 05-20-02, 07:54 AM
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If it were mine, I would check all the connections first....making sure they are clean and tight. I would then measure the amperage the motor is pulling and see if it really is pulling too much current or if the breaker is just prematurely popping. A little diagnostics now might save some unnecessary repair.
Old 05-20-02, 02:56 PM
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I am with MDF99, I too would check all connections especially at the breaker. Check all connections. One loose connection will cause the motor to increase load in amps unneccisarly.

Then like MDF99 said take an amprobe reading at the motor on each hot leg to see what the amps read versus what the full load rating in amps the motor is supposed to read.

If you get a high reading at the motor higher in amps than the full load current rating in amps then you should check your bearings on that fan to make sure they are not dragging due to friction.

Let us know what you find


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