Testing a 7(1/2) hp motor with a 3 hp rotary phase converter
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  1. #1
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    Default Testing a 7(1/2) hp motor with a 3 hp rotary phase converter

    I acquired an old Lagun FU-2 mill some time back and it's eating up a big chunk of my shop. I would like to sell it but would prefer to test it to make sure it operates as expected.

    The motor tag shows it is dual voltage rated for 220/440 vac. Current spec is 16.4.8.2 A. RPM is shown to be 1720. Strangely, it doesn't list the horsepower though some research tells me it is 7 or 7-1/2. Would think though this would also be a dual rating based on the input voltage.

    What I need to determine is, for testing purposes, could I use my 3 hp rotary phase converter that puts out 220 and is rated rated for 15 amps? For reference, it is an older Anderson Converters unit.

    I can't afford to blow the converter as I need it on a regular basis to run my vertical mill but since I will be only running the spindle and table drive motions of the big Lagun, I don't figure I would be using near the full potential of the motor.

    Any input is appreciated.....

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    Any input is appreciated
    More like 5 HP - per Electrical Engineering Pocket Handbook

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    I start motors larger than my converter. The variable is the torque required to get it turning. If it has a clutch, that would help. It wont hurt to try it, just don't try it for too long of time.

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    I would feel more comfortable with 5 hp. May give it a shot over the weekend.

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    So then, as long as the target motor starts up and runs, I should be good. If nothing after a few seconds, then shut it down. I may put a clamp on one of the leads to monitor current as well.

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    As Diving Doug says try it. But don't be surprised if it does not start. I would not expect a 3 HP RPC to put out 15 amps three phase. It may draw that much from the single phase but the output will be less. In a perfect world, 15 amps single phase would give you about 9 amps three phase.

    Bill


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