Re: Variable load for testing phase convertor
- From: David Billington <djb@xxxxxxxxxxxxxxxxxxxxxxxxxxxx>
- Date: Fri, 23 Sep 2005 15:02:11 +0100
I have been told that large gensets are tested with a tank of salt water? and the electrodes connected to the phases are lowered to increase the surface area and therefore current passing through the fluid and so increasing the load. Maybe you could do something on these lines with a large car alternator.
Christopher Tidy wrote:
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 circulating through a needle valve which regulates the load. Plus I'd need a pressure relief valve, contactor etc. It sounds like a neat idea but I'm unsure how much the hydraulic bits would cost.
Any thoughts? Has anyone done this before? I don't want to spend too long on this, because I want to put my effort into the phase convertor, but it would be nice to have a controllable load.
Best wishes,
Chris
.
- Follow-Ups:
- Re: Variable load for testing phase convertor
- From: Robert Swinney
- Re: Variable load for testing phase convertor
- Prev by Date: Re: CNC software highest step rate
- Next by Date: Re: CNC software highest step rate
- Previous by thread: FS: CNC Mill and 12X36 Lathe
- Next by thread: Re: Variable load for testing phase convertor
- Index(es):
Relevant Pages
|
Loading
