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Author Topic: 3-phase power demonstration  (Read 6672 times)

Stephen Swaffer

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Dave Garoutte

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Re: 3-phase power demonstration
« Reply #91 on: January 04, 2019, 12:44:53 pm »

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Jay Barracato

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Re: 3-phase power demonstration
« Reply #92 on: January 04, 2019, 01:59:06 pm »

Yikes!  That costs more than the ANNUAL power bill for my 3-phase machine shop!
Ok I clicked on it, let the ads start rolling in.

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Mike Sokol

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Re: 3-phase power demonstration
« Reply #93 on: January 04, 2019, 04:10:13 pm »

Yikes!  That costs more than the ANNUAL power bill for my 3-phase machine shop!

WOW! Just north of $6,000. Very pretty, but a tad over budget.  ;D
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Mike Sokol
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Mike Sokol

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Re: 3-phase power demonstration
« Reply #94 on: January 05, 2019, 07:01:19 am »

WOW! Just north of $6,000. Very pretty, but a tad over budget.  ;D

With any amount of luck looks like I'll have a Siglent SDS1104X-E to demo next week. At $500 it's a little more affordable than the Fluke. There's a lan port on the scope you can link to your browser so you can watch the display in real time on a computer screen, which I'll output to a video projector. This seems like a great teaching tool since my little 3-phase signal generator will let me change the phase angles in real time. 
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Stephen Swaffer

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Re: 3-phase power demonstration
« Reply #95 on: January 05, 2019, 09:17:48 am »

But it does beg the questions...if the phase angles are off:

What are A/V techs gonna do about it?

What difference will it make to single phase audio gear?
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Mike Sokol

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Re: 3-phase power demonstration
« Reply #96 on: January 05, 2019, 11:32:05 am »

But it does beg the questions...if the phase angles are off:

What are A/V techs gonna do about it?

What difference will it make to single phase audio gear?

There's no way that the phase angles can be off in power made by a generator since it's tied to how the poles are wound. And even if the phase angles were somehow off, there's nothing you could do about it. Of course single-phase gear could care less about phase angles, but 3-phase motors certainly do. But since it will never happen in the field I won't teach it. However, this would be a great platform to demonstrate how phase rotation works as it relates to 3-phase motors, something I will demonstrate in the class.

The reason for building this system is to demonstrate how to measure various 3-phase configurations you might find and what the reasons might be for a strange voltage reading. Now with this system I could show what the original 90-degree 2-phase power looked like, but that's not for this technician class. But it could be interesting if I was teaching an engineering class on phasor theory, something I'm not really qualified to teach but really interesting stuff.
« Last Edit: January 05, 2019, 03:17:25 pm by Mike Sokol »
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Tim Hite

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Re: 3-phase power demonstration
« Reply #97 on: January 05, 2019, 02:08:30 pm »

Notify not working so following along. . .
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Mike Sokol

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Re: 3-phase power demonstration
« Reply #98 on: January 12, 2019, 05:24:50 pm »

Here it is, up and running. I just need to clean up the wiring a bit, but it makes 3-phase WYE 120/208-volts and 3-phase High-Leg-Delta 120/208/240-volts. Good that I had my new 4-channel scope for troubleshooting since I had accidentally flipped the polarity (notice I didn't say inverted the phase) of one of the transformers which gave me some really strange voltage reading with a volt meter. Plus I've added a phase rotation meter to the demonstration. I get to try this out in front of a tech class on Tuesday, so it's working just in time.
« Last Edit: January 12, 2019, 05:32:02 pm by Mike Sokol »
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Mike Sokol
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Mike Sokol

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Re: 3-phase power demonstration
« Reply #99 on: January 17, 2019, 04:47:32 pm »

After I cleaned up the wiring, I packed it up in a little Gator case and took it to my seminar on Tuesday. I did the high-leg delta demonstration for the class, and it worked perfectly making 120/240-volts on the "office taps", 240-volts phase to phase for motors, and 208 volts neutral to high leg. I'm going to repackage this prototype to make it a bit more flight worthy since everything loosened up on the plane. But the concept is sound, and the class asked a ton of questions about 3-phase connections. A few of the old-dogs in the class were able to talk about some of the local venues they work in that have high-leg delta panels, so now they understand why every third row of breakers is off-limits for audio power. And they also know why they can hook across all 3 phases for their chain motors (which are rated for 240-volts) and it will work just fine. Really fun class to teach.
« Last Edit: January 18, 2019, 06:43:37 am by Mike Sokol »
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Mike Sokol
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Re: 3-phase power demonstration
« Reply #99 on: January 17, 2019, 04:47:32 pm »


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