Old military generator

Discuss non-crawler related issues here (keep it sane, please)
Post Reply
User avatar
Lavoy
Site Admin
Site Admin
Posts: 10937
Joined: Sun Apr 03, 2005 8:32 pm
Location: North Dakota
Contact:

Old military generator

Post by Lavoy » Wed Aug 20, 2014 11:58 am

Anybody mess with old military stuff? Went to a local consignment sale a couple weeks ago and a 1943 Mission Water Heater 3KW generator followed me home. 125 volt, 3 phase, used for powering 37 and 40MM anti-aircraft cannon during WWII and Korea. Kind of neat old outfit, got it running and charging, but now what do I do with it, the fun was trying to make it run again.
Lavoy
Parts and restoration for antique and late model John Deere crawlers.
Owner and moderator www.jdcrawlers.com

User avatar
Stan Disbrow
350 crawler
350 crawler
Posts: 2894
Joined: Fri Jul 15, 2005 3:13 pm
Location: Raleigh, NC

Post by Stan Disbrow » Wed Aug 20, 2014 1:06 pm

Hi,

Yup. I have done one. Used it as a radio systems backup. So, it was powering DC supplies which then charged float cell batteries. So, I could simply wire three of em up and have enough watts along with a balanced load. :)

So, you need to dream up some use where you have only 120v stuff and then wire it up as a set of three circuits, instead of the usual two. Remote barn? Hunting cabin?

You could get three 2:1 transformers and wire it all up to run 208v 3p machine tools. 3 kVa is enough for most if you run one at a time. ;)

Stan
There's No Such Thing As A Cheap Crawler!

Useta Have: '58 JD 420c 5-roller w/62 inside blade
Useta Have: '78 JD350C w/6310 outside blade
Useta Have: '68 JD350, '51 Terratrac GT-25
Have: 1950 M, 2005 x495, 2008 5103 (now known as 5045D)

User avatar
Lavoy
Site Admin
Site Admin
Posts: 10937
Joined: Sun Apr 03, 2005 8:32 pm
Location: North Dakota
Contact:

Post by Lavoy » Wed Aug 20, 2014 2:12 pm

This is an M5, the M6 is the same unit but 125 volt, 2500 watt, single phase. According to the book, the generators are pretty much the same, just a few things added for the 3 phase. I would like to convert it to true single phase just for a little added utility. It does have a couple single phase outlets, but since you are deadheading two of the phases, no neutral, and from what I have read, they recommend not pulling more than 1000 watts from each leg. Seems kind of funny, the generator head itself is about the size of a modern 20KVA, so not really sure you are going to hurt it.
Lavoy
Parts and restoration for antique and late model John Deere crawlers.
Owner and moderator www.jdcrawlers.com

User avatar
Stan Disbrow
350 crawler
350 crawler
Posts: 2894
Joined: Fri Jul 15, 2005 3:13 pm
Location: Raleigh, NC

Post by Stan Disbrow » Wed Aug 20, 2014 4:30 pm

Hi,

If you pull to much from those two legs, the third leg starts bucking from the back EMF of the load on the other two. That puts pretty heavy pulses on the rotor, which is bad mechanically.

I found that out trying to run a sizable 220 single phase motor off two legs. I fixed it by sticking a 1200 watt space heater on the third leg as a resistive load. Of course, that eats more fuel, but it smoothed out the running.

The motor I was running didn't care that the phase angle was 120 deg instead of 180. Some motors do care, of course.

Stan
There's No Such Thing As A Cheap Crawler!

Useta Have: '58 JD 420c 5-roller w/62 inside blade
Useta Have: '78 JD350C w/6310 outside blade
Useta Have: '68 JD350, '51 Terratrac GT-25
Have: 1950 M, 2005 x495, 2008 5103 (now known as 5045D)

johnHD
430 crawler
430 crawler
Posts: 50
Joined: Sat Mar 17, 2012 7:22 am
Location: southern wi

Post by johnHD » Thu Aug 21, 2014 4:36 am

lavoy,

if you can find a 3 phase 120/208 motor and a small generator, you could build a motor generator set. you could couple it with a lovejoy or something similar. finding a small 120/240 generator might be a challenge.

1 kva = 1 horsepower (approx) so it will not have a lot of capacity but could be handy to have around.

john

User avatar
shinnery
350 crawler
350 crawler
Posts: 774
Joined: Fri Jan 27, 2006 4:55 pm
Location: Hawley, Texas

Post by shinnery » Thu Aug 21, 2014 11:11 pm

Sounds like a PTO alternator/generator and a 3 phase motor would be just the ticket.
Bryce
No trees were hurt in the creation of this message.
But, many electrons were terribly bothered.

440IC/602, 2-440ICD/831 MM UBU-LP, 445N-LP, 445E-LP, BIG MO 400-M, 4 Star-LP M5-D, M5-LP, M602-LP, M670-LP, G900-LP, G900-D, G1000 Vista-LP Case 580CK

User avatar
Stan Disbrow
350 crawler
350 crawler
Posts: 2894
Joined: Fri Jul 15, 2005 3:13 pm
Location: Raleigh, NC

Post by Stan Disbrow » Fri Aug 22, 2014 4:50 am

Hi,

Well, you only get about 60% efficency from motors and generators, so the conversion loss will be high as it is adding. And, the little genset has little power to start with.

The other issue is the operating RPM of an electric motor is usually around 1200 RPM and generators are 1800 or 3600 to provide a 60 Hz output. So now the frequency of the motor/generator will be off, on the low side.

This, of course is the usual reason to use motor/generator sets. To convert the 60Hz of US power to the 50Hz of European power. Or, in the case of mainframe computers, 400 Hz power. The higher the frequency, the smaller we could make the DC power supplies ;)

Anyway, one has to find a 125v 3p motor with a shaft speed that matches the generator chosen or be off in frequency. Unless the load is resistive, frequency matters.

Stan
There's No Such Thing As A Cheap Crawler!

Useta Have: '58 JD 420c 5-roller w/62 inside blade
Useta Have: '78 JD350C w/6310 outside blade
Useta Have: '68 JD350, '51 Terratrac GT-25
Have: 1950 M, 2005 x495, 2008 5103 (now known as 5045D)

johnHD
430 crawler
430 crawler
Posts: 50
Joined: Sat Mar 17, 2012 7:22 am
Location: southern wi

Post by johnHD » Sat Aug 23, 2014 7:22 am

good point stan. gearing would be required.

i saw a farmer that had taken a large single phase military generator and connected it to a 15kva distrubution pole top trainsformer.

he had it connected to the x2 and x4 bushings, with the farm connected to the x1, x 2-3 and x4 bushings. it made 120/240 for his farm.

however, the frightening thing was that he had the high side H1 and H2 bushings just sitting there energized at 4160v. the transformer sat on a shelf he had mounted to the frame of the generator.

how he never got killed by his contraption is beyond me. i gave him a couple of plastic squirrel guards to cover the bushings so his grandkids didn't get into it.

(i work as a lineman trainer for a midwest utility)

john

User avatar
Stan Disbrow
350 crawler
350 crawler
Posts: 2894
Joined: Fri Jul 15, 2005 3:13 pm
Location: Raleigh, NC

Post by Stan Disbrow » Sat Aug 23, 2014 7:59 am

Hi,

And, the problem with gearing is having even greater losses when the poor thing hasn't anything to lose in the first place.....

I am not properly schooled in the Big Stuff, as I call it. But, I do not need your level of education in it to know I do not want to come within about a hundred feet of that lash up! :shock:

In the fire service work I did, the utility company guys would regularly show up with a trailer with two short poles and transformers. They would plug into the station at one end, then light a bulb at the far end. They used hot dogs to simulate fingers and other body parts on the HV side, and the end result was never pretty....


Stan
There's No Such Thing As A Cheap Crawler!

Useta Have: '58 JD 420c 5-roller w/62 inside blade
Useta Have: '78 JD350C w/6310 outside blade
Useta Have: '68 JD350, '51 Terratrac GT-25
Have: 1950 M, 2005 x495, 2008 5103 (now known as 5045D)

johnHD
430 crawler
430 crawler
Posts: 50
Joined: Sat Mar 17, 2012 7:22 am
Location: southern wi

Post by johnHD » Sat Aug 23, 2014 8:43 am

stan,

that is also true.

short of rewinding the generator maybe lavoy would be better off to buy the ack ack cannon it was designed to run!

i have to do a "wires and fires" demo for some call center gals when i get back from vacation.

we do the hot dog thing too, plus we have a little stuffed squirrel to blow the fuse on our demonstrator.

old lineman adage - "if you don't know what it is, don't touch it. you will live longer"

john

Post Reply

Who is online

Users browsing this forum: No registered users and 36 guests