[thingstodo]

Second part of the posting

There are a few more details, plus some assorted ramblings below.

I decided to split the spreadsheet into three tabs, for the three trials I did. The trials were different in what was measured and how it was measured. I thought that I was improving as I went along. Now I'm not so sure.

Settings:
The VFD is rated for 240 VAC three phase, 15A and will do 22A for about 30 seconds. It is set for linear V/Hz output.

Change - VFD boost settings. This is a percentage of the rated voltage, and the VFD allows the setting to vary from 0 - 40%. Changed from 0% up to 37%

Measure - motor temperature, motor current, scale reading

The VFD will display the output current, output voltage, or output frequency. This particular surplus unit appears to have an issue with the output current, since it displays the same value no matter what current it is actually sending out. The output frequency is always the same - 0.9 Hz. The output voltage displayed on the VFD never matched what I was measuring with the AC meter.

I have a clamp-on meter on one phase of the AC to the motor, another meter showing output voltage phase - phase, a hand-held infra-red meter for motor temperature (at the same spot each time - the meter is duct taped to the motor), a meter on the DC bus voltage of the VFD to make sure that I am not running out of power from my battery bank. I ran out of meters so I don't have the DC current from the battery bank, which would have been nice to show the power in versus power out for the VFD.

The results are not what I expected. That seems to be a recurring theme in the tests that I set up. The battery bank ran out of current the first time I ran the tests. So I fed 240 VAC into two of the terminals on the VFD, to supplement the battery power. I then spent the rest of the day ensuring that I did not over-charge the battery bank, or charge it too quickly. You will notice the DC voltage changes around 30 - 35% boost

I measured as high as 212% of the rated motor current, which gave me a reading of 100 pounds of force on the scale. Working that back through the pulleys, the motor put out 27.27 foot-lbs of torque. The 5 HP motor is rated at 15.04 foot-lbs, so the peak I measured was 181% torque. I was not able to put 300% current into the motor (my estimate) so I think it was reasonable to get less than the 220% torque listed in the motor specs.

These results are not what I remember them being. Some of the things that I thought were obvious about the setup - so I didn't write down the details - turn out to be important and not easy to interpret from what I did write down.

I don't know why I stopped testing when I got to the end of the 0.9 Hz set. I should have redone the whole test at 1.8 Hz and 2.7 Hz. If those showed any interesting trends, I should have added more test runs between them. I didn't even get up to 300% current. The last set of tests that I ran I didn't write down the motor current (!!!) That seems like a pretty important thing to miss.

I will be writing up what I want to see for the test before doing them, predicting the results, then performing the test and collecting the data. Working from memory while you are out in the garage does not seem to work very well.

You may very well wonder why I am using a test motor and a test VFD instead of using the equipment that I want to use in the truck. I didn't have a VFD with enough power to drive the 40 HP motor at 300% current when I did the tests, and I still don't have the VFD operational. It's just a whole lot safer to work on smaller (scale) models for testing than it is to perform full scale tests. I want to get some practise testing, predicting, logging. With 40 HP, 220% torque will be 120 * 2.2 = 264 foot-lbs of torque. That's a lot of torque to measure. My present setup will not handle it.

First three tabs are for trials 1,2, and 3. They are a bit of a mess.

VFD Settings is a listing of the parameters for the test VFD, an Allen Bradley 1333.

Motor Data lists the information from the nameplate for each of the motors that I have.

The test motor is:
reliance electric sabre 5 hp
184t frame
hp 5
460 VAC 3 phase design b type p
rpm 1745 amps 6.6
60 hz, ambient 40c s.f. 1.15
cont duty insul class f
enclosure prot code j
pf 83, nom eff 87.5
weight 69 lbs