AC Delco Generator question

[gap]

Hello all,
We just picked an ol' reliable 115KW genset powered by a normally aspirated 671 Detroit with an AC Delco Generator end. Can't get much simpler--except for the fact that I'm having a heck of a time finding someone who can tell me which generator windings (12 wire--T1 thru T12) get tied together for 480V 3phase. It is currently configured for 208V 3phase. The generator end is model #E5278E9 S/N 39-D-65. Detroit and AC Delco have been dead ends, and without a service contract, Genset Service Companies want to charge a service call for this info. Was thinking I could also ohm-out the windings to figure out how to get them in series for 480V. Any advice would be greatly appreciated.
Regards,
Scott

 

[gap]

Re: AC Delco Generator question

By the way, the tag on this generator does not have the usual connection diagram seen on most motors. Please help. I'm looking at paying two hours travel to start with to get Detroit Generator Service up here. Scott

 

[Ed MacLaren]

Re: AC Delco Generator question

The standard three-phase, dual-voltage (240/480) winding has 12 leads, (sketch below) but doesn't have a 208 volt connection.

The machine you are dealing with must have some kind of tapped winding arrangement, if you can get both 208 and 480 volt connections.

Ed

[ June 24, 2004, 11:12 PM: Message edited by: Ed MacLaren ]

 

[hurk27]

Re: AC Delco Generator question

I looked up sevral listing's on this gen set and none list 208 they are 240/480 3-phase

 

[hurk27]

Re: AC Delco Generator question

Ed
Is it posable to connect a 12 lead generator ether delta or "Y" if it is then wouldn't you have 208/120 when it is connected low "Y" and 480/277 in high "Y"? And when you connect it Delta then you would just have 240 low or 480 high.

I'm just curous as I have never herd of it but just wondered if it was possable?

 

[Ed MacLaren]

Re: AC Delco Generator question

Is it posable to connect a 12 lead generator ether delta or "Y"

Yes, if all 12 leads are accessable, you could connect it either way, however, each winding "section" will be designed to produce a rated voltage at rated speed and excitation.

Let's say each section of each phase is designed to produce 138.7 volts.

The terminal voltages would be approximately-
Parallel-wye = 240 volts
Series-wye = 480 volts
Parallel-delta = 138.7 volts
Series-delta = 277 volts

There are no connections that will give 120/208 volts.

Ed

[ June 25, 2004, 09:33 AM: Message edited by: Ed MacLaren ]

 

[ronaldrc]

Re: AC Delco Generator question

Hurk I agree with your comment.

How would this differ from a transformer with the same windings? Primary being the field or rotor and the secondary being the armature.

If you configure the secondary in a wye it would produce 120/208 with parallel windings and 277/480 in series.


Has anyone tried this and measured the voltages?

[ June 25, 2004, 07:54 PM: Message edited by: ronaldrc ]

 

[gap]

Re: AC Delco Generator question

Thanks for the replies. This is a military unit. All leads are accessible and and terminate in a box where the leads are connected via a 'bolt-on' panel with buss bars. From the log book at one time it had other panels preset for each voltage configuration so it could be changed quickly. Unfortunately we only got the 208/120V panel. Thanks again for the pictures!
Regards,
Scott

 

[gap]

Re: AC Delco Generator question

Just got off the phone with the folks that made the voltage regulator. They said for 480V connect in Hi Wye--T10,11,12 for neutral, T4-T7,T5-T8,T6-T9--T1,2,3 for line. We're going thru the engine now so it'll be a bit before we can fire it back up to see. Does this make sense?
Scott

 

[ronaldrc]

Re: AC Delco Generator question

Ed or some one familiar with generators help me here a little bit.I don't think the 277/480 rating is just a matter of doubling the 120/208 I think this is a seperately engineer voltage rating.


I don't believe you will have a full 480 volts with the high wye.

I drew a diagram that shows it the way I see it. The high wye configure would yield 416 volts because of the 3 phase wye instead of 480.

I think I looked at this right correct me if I'm wrong?




[ July 05, 2004, 09:34 PM: Message edited by: ronaldrc ]

 

[Ed MacLaren]

Re: AC Delco Generator question

Ronald,

Your numbers would be correct for a machine that was designed to produce 120 volts in each section of each phase, at rated speed and excitation.

If the generator in question has nameplate ratings of 240 and 480 volts, each section of each phase is designed to produce 138.7 volts, as outlined in my post of June 25 above.

Ed

 

[ronaldrc]

Re: AC Delco Generator question

Hello Ed Hope everything is going good.

In Scotts post he said it was setup for 208 and he wanted to change it to 480.

I'm not that familiar with common winding voltages on transformer or generators I just assumed the winding was 120 per winding since with the wye configure he is getting 208 and your higher voltage in the wye configure is 1.73 x your neutral voltage.

Is the standard winding setup for 138.7 volts?


Thanks for your reply

[ June 28, 2004, 08:05 PM: Message edited by: ronaldrc ]

 

[gap]

Re: AC Delco Generator question

Not sure if this means anything, but the log book says--rewired from 208/120V to 460V... I figured that's what they make the voltage adjust screw for--I've always figured 460/480V to be the same. Just more info. By the way I just read the full logs and found out this set has been moving oxygen to the spaces shuttles since the early 90's. Still see cross hatching on the cylinder walls--new rocker arms, rehose, filters and she's good to go for another ten plus...boy I love those old 671's--not even any glo-plugs--straight compression fired. I work for U of Florida and we're at the end of our fiscal year--aka 'out of loot'--so it'll be another month before we can install this set but really do appreciate the input. I went out on a limb buying this old--some say--P.O.S. instead of getting a new perkins or similiar but I've seen some beat down, 30 yr old shrimp boats with these sets still chugging away in the salt. Some things we used to build are hard to kill. Can't say the same for things built today. I'd hate to burn it up with a miss wire. Everyone's input is greatly appreciated...
Regards,
Scott

 

[ronaldrc]

Re: AC Delco Generator question

Scott if Ed is right and he usually is and the voltage per winding is 138.7 volts at rated speed that would give you 480 volts in the high wye configure.

I would ohm the windings out and if they coincide with the numbers in Eds diagram I would hook it in the high wye and try it.

Remember you will have 277 volts from each leg to neutral not 240 volts.

Good luck if it smokes send Ed the bill.