Electric motor load

Old 03-20-03, 07:17 AM
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Electric motor load

I just reworked the pump on muy pressure washer and I am going to set the pressure with the unloader. When it was new I checked the load draw at 22. The nameplate says 5 hp @ 25A It has a service factor of 1.15, the motor is a Baldor. When I probe it last night with free flow it had 15 a draw. I assume as I increase load curent will go up and was just wondering how far would be good to load it? Just curious, Thought I would go to 22 and check pressure. I dont have the same meter I calibrated it with 18 yrs ago, how much difference has anyone found with amprobes?
Old 03-20-03, 08:38 AM
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Table 430.148 indicated this is a 5 HP 230 volt single-phase motor. The motor should be operated with a starter that has over-load devices that will release the starter if the running current exceeds the name-plate current. This is to avoid an excessive current that will damage the windings because of over-heating.

The NEC requires an OL device that does not exceed 125% of the name-plate full-load current. If you protect your motor with such an OL devise and the motor operates at full-load without overheating and without OL devices releasing the starter you'll be OK. Consider measuring the line-voltge with the motor operating full-load. The line-voltage may be less than the name-plate voltage. Good Luck!!!!

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