Why is this 3 phase generator 133 volts?

[Iron Beaver]

Browsing eBay for things I can't afford to build into projects I don't have time for, I ran across this Mecc Alte industrial 3-phase generator head:

MECC ALTE GENERATOR END MODEL ECP34 L14 New Old Stock SAE #1 with SAE #11-1/2 | eBay

Find many great new & used options and get the best deals for MECC ALTE GENERATOR END MODEL ECP34 L14 New Old Stock SAE #1 with SAE #11-1/2 at the best online prices at eBay! Free shipping for many products!

www.ebay.com

But why is it 133 volts? Is this measured between the legs of the 3-phase or between an arbitrary leg and neutral?

 

[TurnipTruck]

I have heard that military aircraft use 400vAC 3phase.

 

[Iron Beaver]

Well this doesn't generate 400V, at least it's not mentioned on the nameplate. I remain mystified

 

[wyliesdiesels]

company is still in business. maybe ask them?

BTW the ebay listing has the wrong m/n. The nameplate has correct m/n

ECP34A 4 pole | Mecc Alte

Mecc Alte ECP34A 4 pole alternator - description, general characteristics, technical documents and overall dimensions drawings

www.meccalte.com

 

[cvairwerks]

Aircraft would be 115 VAC/ 400 cy.

 

[Norcal]

I have heard that military aircraft use 400vAC 3phase.

Aircraft use 200V 3Ø 400 Hertz, weight is a major concern with aircraft, 400 HZ allows smaller components. 400V is used in the 50HZ world

 

[cvairwerks]

Every one I’ve worked on that had AC power, was 115 and not 200.

 

[mogandave]

Why not call the manufacturer and ask them?

 

[Sumboodie]

Aircraft would be 115 VAC/ 400 cy.

The tests sets we used for missile systems were 120v 400hertz.

Had to use a frequency converter to use shop power, or a gen set that's used for powering the planes.

 

[haveissues]

I'm guessing it is to get a close enough to 120v single phase output. You get 133v between neutral and one of the phases.

 

[wyliesdiesels]

I'm guessing it is to get a close enough to 120v single phase output. You get 133v between neutral and one of the phases.

11% overvoltage? Thats pretty high...

 

[PoorUB]

I looked around and it seems common on 460 volt 3 PH generators. Probably just the way they get wired up. All I know is I can't explain it.
https://www.absolutegenerators.com/...12_Wire_Reconnectable_Connection_Diagrams.pdf

 

[mike93lx]

11% overvoltage? Thats pretty high...

Just run everything off 200' of cord. Problem solved

 

[TRWham]

Because it produces 230 V line to line, therefore 133 V line to neutral.

 

[mike93lx]

Because it produces 230 V line to line, therefore 133 V line to neutral.

How do you come up with that?

 

[American Locomotive]

How do you come up with that?

120/208 "wye" has a 1.73x relationship when comparing the phase to neutral and phase to phase voltages.

133 x 1.73 = 230v. So it's a wye wound 133/230v generator. Some single phase sfuff might be "okay" on 133v. Motors will probably tolerate it, and it might also explain the existance of those 130v light bulbs.

 

[mogandave]

120/208 "wye" has a 1.73x relationship when comparing the phase to neutral and phase to phase voltages.

133 x 1.73 = 230v. So it's a wye wound 133/230v generator. Some single phase sfuff might be "okay" on 133v. Motors will probably tolerate it, and it might also explain the existance of those 130v light bulbs.

Would the three phase "generator" create a neutral?

 

[American Locomotive]

Would the three phase "generator" create a neutral?

A delta wound 3 phase generator will not have a neutral. But a wye wound generator can.

In a wye wound generator, one end of each coil is connected to one another. This connection is called the "star" point, and is always at 0v no matter what. That means it can serve as a neutral and creates a ground reference for the generator.

 

[haveissues]

This 3 phase generator manual specifically addresses using the 133v output.

https://manualzz.com/doc/o/16365a/wacker-neuson-g70-mobile-generator-operator-s-manual-connecting-a-220%E2%80%93240v-3%C3%B8-load-and-multiple-127%E2%80%93133v-1%C3%B8-loads

 

[fitter30]

Would running 400 cycles read the wrong voltage on a cheap meter?

 

[Iron Beaver]

I think cheap meters read peak voltage and multiply by a constant to get what would be the true RMS voltage of a pure sine wave. I think true RMS meters actually square, integrate, and square root whataver comes in. The people here who actually know will likely correct me in 3...2...1...

 

[wyliesdiesels]

Must be for a special use case as i dont know of anything that calls for 230v/133v 3 phase 60hz...