"Don Foreman" wrote in message
...
On Sun, 06 Mar 2005 16:52:53 GMT, "Karl Townsend"
remove .NOT to reply wrote:

If there's anyone out there with Total Recall, you might remember I've had
a
lot of trouble with my irrigation well. Its a 20 hp single phase and they
aren't made or serviced anymore. I have to move up to three phase.

I've bought a 50 hp VFD drive and a 75KVA transformer to produce 440 three
phase. Before I buy and install a new 30 hp. pump, I want to test this
under
load. I have a 30 hp motor, I'm looking for ideas on how to create 30 hp
of
mechanical resistance and know I have that much load.

For how long? 30 HP is over 22 KW, a fair amount of heat.

For short-duration tests, you might use an automotive drum or disc
brake. You can measure torque with a spring scale. At 1750 RPM,
torque would be about 90 lbf-ft so a 1-foot arm and a 100 lb spring
scale would be about right.

Most VFD's will read out torque, current draw, etc.. I suppose it's all
derived from the speed and current draw, in any case there should be enough
information to determine whether the VFD/Transformer combo can handle the
load. I would monitor the voltage output of the transformer during the test.
You can reduce the voltage output from the VFD, within its range. I don't
know if it would react quickly enough to stabilize dips in the transformer
output.