Quote:
Originally Posted by Intrigued
Are you over-volting this motor to give it more horsepower? Even with a reduction ratio of 3:1 I'm not sure 2 HP will provide enough oomph to pull the compressor, unless it is a fairly weenie one. I don't remember how old-school my A/C learnin' is, but I remember at the GM school an instructor saying that a compressor under full load can require as much as 20 horsepower...
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Outside of commercial/industrial applications, an A/C compressor is not going to use 20HP of power constantly. Even a large central A/C unit is only 4HP or so at most. It would not be unreasonable for a compressor to use 20HP for a split second on startup, however. Therefore, you'll actually need two current limits. One that acts instantly if the current exceeds LRA (Locked Rotor Amps) and another with a time delay of a few seconds that prevents the current from rising above FLA (Full Load Amps) for an extended time.
Also, belt drive for A/C compressors is long obsolete. Direct drive is the way to go. (Indeed, modern A/Cs even direct drive the fans.)