Variable load for testing phase convertor

Christopher Tidy · 2005-09-23T03:26:24+00:00

Hi all,Soon I should have most of the components necessary to build my phase convertor. I'd like to do a few trial runs in which I wire the components together and test the convertor's performance before I go to the time and expense of building a metal chassis to mount it on.So today I was wondering how I could create a variable load in the range 0.5 to 2 hp. Has anyone done this before? The only three phase workshop machine I have is a power hacksaw with a 1 3/4 hp motor. This runs through a static phase convertor I built and I don't really want to disturb the wiring if I can avoid it.Ideas I had are as follows, with some disadvantages listed:Motor bolted to wooden board. Insert 2" x 4" under pulley and lever upwards to create load. Load control is a bit crude, as is the whole setup, but I've used it before and it works after a fashion. Sets fire to wood, too.Motor bolted to board with slightly more sophisticated homebrew braking system, possibly allowing weights to be loaded onto a lever. Still crude, but a bit more controllable.Motor driving variable pitch propeller in small tank of liquid. Neat, but I don't know where to get a variable pitch propeller for little money, or how to match it to the motor.Bolt car brake disc/drum to motor pulley. Use hydraulic calipers to apply load. Could be quite neat, but it would be a faff to build because of needing a reservoir, flaring pipes etc. I'm also not sure how to regulate the pressure. Plus car parts dealers in our area charge big $$$ for car parts.I rather like my final idea. A while back a friend offered my a hydraulic pump from a concrete crusher (i.e., a test rig for measuring compressive strength). I think it has a 2 hp three phase motor and is the kind where the motor is mounted vertically on top of the pump, with the pump hanging down into the reservoir. So I thought I could cut a 47 kg propane cylinder in half, make a plate to cover the opening and mount the motor/pump unit on top. Then I could have the oil...

Sep 23, 2005 20 Replies

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Christopher Tidy 20 years ago

Thanks for the warning. I've seen this happen and it's pretty scary. If I were to take this route I'd certainly build a shield of some sort around the valves and pipework.

Chris

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Variable load for testing phase convertor

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