Power waveforms & MEP generators

[rhurey]

Recently picked up a MEP-803a. One reason that I decided to get this was to solve an annoying problem, one of our UPS units refused power from our gas generator. (A Brigs & Stratton unit.)

So part of inspecting the MEP was making sure it looked like it would solve that problem. So out comes the cheap scope.

As a baseline, Snohomish County PUD #1 utility power:


The B&S unloaded:

Shaky, but still decent.

And with a 3KW load:

Well, that's not pretty. Need to see how balanced that load is.

The MEP-803 unloaded:


MEP-803a w/ 12KW load:

Well, that's a lot better.

So, the sine wave is pretty decent.

Oh, some other random ones...

An APC BRG1500 UPS:


And a Smart-UPS 1500:

 

[Guyfang]

If you ever get a chance to scope a 400 hz model generator, that would be of interest to me. Something in the order of the 15-60 KW range, Precise Power sets. When I was in HAWK and PATRIOT, our generators provided prety clean power, although when ever the scope dopes and radar mechanics could not solve a problem, it was our "Filthy" power. I once scoped our 150 KW Turbine generator set and the scope looked like a printed picture from a text book.

 

[rustystud]

I see you got the generator running ! That's good !

 

[rhurey]

I see you got the generator running ! That's good !

Yeah, right up till it over heated. Suspect the T-stat isn't opening from IR gunning the hoses and all. (Radiator is 95, block is 240, hoses are 200 hear the pump, 95 near the radiator) So hopefully a new one will show up before next weekend. I also suspect it's low on coolant from what I could drain out, but need to get the T-stat verified.

 

[rustystud]

Yeah, right up till it over heated. Suspect the T-stat isn't opening from IR gunning the hoses and all. (Radiator is 95, block is 240, hoses are 200 hear the pump, 95 near the radiator) So hopefully a new one will show up before next weekend. I also suspect it's low on coolant from what I could drain out, but need to get the T-stat verified.

Well at least a thermostat is not a big deal to change out. Hopefully after this it will run good for you.

 

[Daybreak]

Yeah, right up till it over heated. Suspect the T-stat isn't opening from IR gunning the hoses and all. (Radiator is 95, block is 240, hoses are 200 hear the pump, 95 near the radiator) So hopefully a new one will show up before next weekend. I also suspect it's low on coolant from what I could drain out, but need to get the T-stat verified.

Howdy,
Remember, there are 2 drain petcocks for the cooling drain. 1 at the bottom corner of the radiator. The other is a bear to get to, right at the front of the unit under the water pump (block drain)
I cheat by using the pallet forks and fill up the radiator with the whole unit leaned back with maybe a 20 degree tilt. I fill it, level it out, dead crank it for 20 seconds ,then I lean it back and finish filling coolant.

 

[Triple Jim]

Nice scope traces, thanks. I always thought that "modified sinewave" was a very optimistic term for that type of inverter. They're still better than the old square wave ones though.

Is your Briggs and Stratton unit a straight motor-generator type, or is it an inverter type?

 

[rhurey]

Nice scope traces, thanks. I always thought that "modified sinewave" was a very optimistic term for that type of inverter. They're still better than the old square wave ones though.

Is your Briggs and Stratton unit a straight motor-generator type, or is it an inverter type?

straight motor-generator.

Funny you mention the square wave... Had an old Back-UPS 400 laying around:

 

[Triple Jim]

Must not be too old, since that's a modified square wave too. It's the old ones with big heavy transformers in them and TO-3 transistors bolted to the outside that were real square wave inverters. They work OK too, but not so great for induction motors.

The only thing I can think of that would cause such a noisy output from the Briggs generator is dirty or worn slip rings, if it has brushes.

 

[DiverDarrell]

That's a nice wave form from the 803, better than I would have expected. Good to see another pnw'er on here

 

[rustystud]

That's a nice wave form from the 803, better than I would have expected. Good to see another pnw'er on here

And I'm chop liver ? Ryan just lives over the hill from me. I see your over the pond.

 

[Speddmon]

I've been wanting to bring home a scope from work for some time now and do the same thing to my MEP-003a's to see how they compare with grid power. Seeing your test has inspired me to do that when the weather breaks.

 

[DiverDarrell]

And I'm chop liver ? Ryan just lives over the hill from me. I see your over the pond.

Good to see other PNW'er'S on here. I work on that side of the water.

 

[Triple Jim]

My 003A has a pretty clean sine wave output. Next time I have the house running on it, I'll try to get a photo of my old analog scope's display.

 

[rustystud]

Good to see other PNW'er'S on here. I work on that side of the water.

Good to see you too. So you live in the Seattle area then and work over in Port Orchard ? Own any MV's yet ?

 

[JRM]

My customer who had a 802A in the back of his truck (and the reason I now own a 803a) lives east of Cougar WA off grid cabin up on curly creek- He is not a member here though. He keeps the 802 in one of his older pickups as he cannot leave it at the cabin due to theft

 

[fcbrants]

Is that a software based oscilloscope?

Would you mind sharing the details about the oscilloscope?

Thanks!!

Franko

<Snip>

So out comes the cheap scope.

As a baseline, Snohomish County PUD #1 utility power:
View attachment 616545

The B&S unloaded:
View attachment 616546
Shaky, but still decent.

And with a 3KW load:
View attachment 616547
Well, that's not pretty. Need to see how balanced that load is.

The MEP-803 unloaded:
View attachment 616548

MEP-803a w/ 12KW load:
View attachment 616549
Well, that's a lot better.

So, the sine wave is pretty decent.

Oh, some other random ones...

An APC BRG1500 UPS:
View attachment 616550

And a Smart-UPS 1500:
View attachment 616551

 

[DieselAddict]

Can you do a test with it in 3 phase mode?

I expect the waveform to be a little better in 3 phase versus single phase.

 

[rhurey]

https://www.amazon.com/gp/product/B00FYGEFYM/ref=oh_aui_detailpage_o00_s00?ie=UTF8&psc=1

It was about 1/2 that price ($65) when I bought it. Mainly for looking at power from the generators and some other (relatively) low frequency stuff.

Works ok. Definitely not the HP I've used before, but for the price it was a "Meh, if it sorta works it'll be worth it" thing.

 

[rustystud]

https://www.amazon.com/gp/product/B00FYGEFYM/ref=oh_aui_detailpage_o00_s00?ie=UTF8&psc=1

It was about 1/2 that price ($65) when I bought it. Mainly for looking at power from the generators and some other (relatively) low frequency stuff.

Works ok. Definitely not the HP I've used before, but for the price it was a "Meh, if it sorta works it'll be worth it" thing.

Ryan, your sounding like my son now, what with all the "Meh" going on. That's all he says now. Like how was your day ? Replay "Meh" . What are you doing ? "Meh" . Are you going out with your friends tonight ? "Meh" . Meh, Meh, Meh, drives me nuts ! So I started saying it back to him. Drove him nuts ! Payback !