Sean Posted November 23, 2019 Report Share Posted November 23, 2019 Hi everyone, I recently purchased a world aire 10hp 120 gallon 2 stage compressor, when I looked at the compressor it would only buzz when turned on so having fixed a few of these issue I knew it was a capacitor issue. I got the compressor home changed out all 4 capacitors and was in business (or so I thought). Upon startup the compressor is drawing far too many amps. The compressor has a Baldor motor that is rated at 39 running amps, during normal running it’s is drawing between 45 and 50 amps during start up it is drawing between 320 and 370 amps depending on cut in pressure. My shop currently has a15 kva transformer on the pole with a 1/0 drop 75 feet to the building, from the breaker panel I have 60 ft of 6 awg wire and a 60 amp breaker. I have checked the unloader valve and it works perfect. I have spoken to a couple motor shops and they think it’s a voltage issue and when I speak to the power company they think it’s a motor issue. Do any of you know if anything internally in that motor can cause it to draw way too many amps on start up PLEASE HELP!!! Quote Link to comment Share on other sites More sharing options...
wingless Posted November 23, 2019 Report Share Posted November 23, 2019 Welcome to the forum. When the compressor is not running, what is the measured voltage at the plug? Same question for when running? What are the motor nameplate markings? Quote Link to comment Share on other sites More sharing options...
Sean Posted November 23, 2019 Author Report Share Posted November 23, 2019 Voltage is 245 when not running, upon startup voltage drops to 180 and during normal running voltage is 230. Quote Link to comment Share on other sites More sharing options...
wingless Posted November 23, 2019 Report Share Posted November 23, 2019 Thanks for the information and the image. The building wiring and the compressor wiring sound fine. The compressor off voltage is a little high, but not a problem. The initial voltage sag and the operational voltage are fine. The 15 VAC difference between compressor off and running is concerning, but it is probably from the excessive current. My guess is the system has excessive rotational resistance, causing the motor to work REALLY hard. A good starting point is to measure the operational motor shaft RPM. It should be 1,725. If less that also points at excessive resistance. Disconnect the belt and spin the motor shaft by hand. It should spin freely. Try the same on the compressor. It should not feel gritty. It should be hard to impossible to turn by hand. That 10 hp compressor might have a vent to atmosphere valve that would permit feeling the compressor crankshaft when turning by hand. How is the visual appearance of compressor oil? Is the compressor air filter clean? Does the operational current drop when running w/o the air cleaner? Quote Link to comment Share on other sites More sharing options...
Sean Posted November 24, 2019 Author Report Share Posted November 24, 2019 The compressor oil is new and thanks so much for the reply I am going to chase the rotational force today and measure the rpm, I will let you know the results later. Thanks again!!! Quote Link to comment Share on other sites More sharing options...
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