The right meter for this test setup? 3

[KirbyWan]

Howdy all,

I need to test a three phase four wire motor and the test setup calls for a watt meter. I'm a bit swamped by all the choices available and don't want to spend more than I need to, though I'm happy to pay for quality equipment that meets my needs. I've included a couple of pics from the manual that defines the test setup and the measurements required. I was thinking a Yokogawa CW500 or Fluke 437, but before I drop 3 grand or more on a meter, I want to make sure it does what I need and there isn't a less expensive option that meets my needs. I'm a mechanical engineer so this is a bit outside my knowledge base.

https://files.engineering.com/getfi...677-9188-eb64b72943f2&file=865_test_setup.PNG

https://files.engineering.com/getfi...6-8b71-fbc676896a6a&file=865_test_results.PNG

Thank you,

-Kirby

Kirby Wilkerson

Remember, first define the problem, then solve it.

 

[ScottyUK]

Very odd to see a motor star point connected to the system neutral. Is this typical of aircraft motors?

With the star point connected to the neutral you need three CT's, whereas with a conventional 3-wire motor you could get away with two CT's. It's a 400Hz system so that might complicate it a little because of the higher bandwidth needed.

Either of the instruments you've mentioned could do this and more, but probably overkill if that's all you're wanting to do. Yokogawa's WT333E would also do what you're asking, as would a Voltech PM300 although the latter are only available on the aftermarket now. At the upper end of the market, Tek's PA4000 is fabulous but I can't justify buying one...

 

[catserveng]

Are you doing extended testing or testing a large number of units? Why not rent? I use these guys a lot and they have the Fluke 437,

https://www.atecorp.com/products/fl...MIgZOV7MGP5AIVh9dkCh1kxAGaEAAYAyAAEgLr4PD_BwE

I usually rent a piece of equipment like this a few times before I buy, lets me put it thru the paces and I can see if it is tough enough to survive most of the work environments I end up in.

MikeL

 

[KirbyWan]

ScottyUK,

I can't answer this question. I'm kind of new to actuators/motors. Most of my aviation experience so far was structural. I'll look around for the other choices you've mentioned.

Catserveng,

This will be going into a test stand for a unit that we regularly get in for testing. So renting is not an option, but it might be a good choice to see if it meets our needs before purchase. I could use 3 individual power meters, if that would be less expensive. If there's a panel mount version I could create a test box with banana plugs and wire the three meters internally. I was trying to find a tolerance requirement in the Component Maintenance Manual (CMM) but it just has the average maximum Amp and Watt measures.

Thanks for everyone's help,

-Kirby

Kirby Wilkerson

Remember, first define the problem, then solve it.

 

[KirbyWan]

The 400 hz is the sticking point. The CW500 looks like it would suffice, but it only reads 44 to 70 Hz. So it's focused on standard line power. However in the user manual it says it can do higher frequency if I use one of these current probes (see the attachment picture which has a snip of the manual). Can someone confirm that this will provide meaningful readings for a 400 Hz system? But only if I use one of the current probes instead of hooking directly to the current inputs? It's about 1/4 the price of a Fluke 437 II. I was thinking I could use the fluke 434, but it also doesn't go to 400 Hz. Only the 437 does.

If all I need is the power meter function, can I use 3 single phase power meters that could do 400Hz? I'm thinking this may be a much cheaper option than the high end test equipment that is designed to do everything.

Thanks for your input.

-Kirby

https://files.engineering.com/getfi...b298-59882d29a89d&file=CW500_maunual_snip.PNG

Kirby Wilkerson

Remember, first define the problem, then solve it.

 

[FreddyNurk]

It does depend on the meter its hooked up to, but I seem to recall that the Rogowski coil current measuring arrangements had a higher bandwidth than normal power frequencies. Whether the instrument its connected to can do anything with that higher bandwidth is another question. I believe there's at least one Fluke unit that uses them.

EDMS Australia

 

[thermionic1]

We use the Arbiter 931A and find it both easy to use and very accurate. They offer CT's as well. It has a wideband mode for up to 3kHz. There is a simple command line serial interface for external data collection.

https://www.arbiter.com/catalog/product/model-929a-three-phase-power-meter.php

 

[KirbyWan]

So guess what. After asking a lot of questions about this, someone remembered that this was being done at one time and dug around and we found a powersight PS3000 power analyzer. That's what was being used before staff changes caused a gap in the tribal knowledge. Of course the spec says it can measure 50 Hz or 60 Hz systems. How far off will this be for a 400 Hz system?

-Kirby

Kirby Wilkerson

Remember, first define the problem, then solve it.

 

[catserveng]

Powersight offers a number of different options, it may be that your PS3000 has had a firmware upgrade to allow 400Hz operation.

I'd check with Powersight, they have pretty good support and seem helpful in upgrading existing meters instead of just trying to sell you a newer model, at least in my experience.

MikeL.

 

[KirbyWan]

The Powersight PS3000 is capable of measuring 400 Hz, it's just not obvious going through their website till you dig into the manual. It uses current clamps and has settings designed for aircraft electrical systems of 115VAC 400Hz. Using the front panel on the meter it will only give the power of all three phases summed together, but if you install the included software and hook it to a PC using a serial cable, it will provide the power for each phase individually. It seems like it's the right solution for this application. Thanks for everybody's help. This has been a learning experience.

-Kirby

Kirby Wilkerson

Remember, first define the problem, then solve it.

 

[waross]

Thank you for the update.

Bill
--------------------
"Why not the best?"
Jimmy Carter