If a person had two small 110VAC generators. Ganged the commons and fed one
generator into each leg of a 220VAC single phase circuit, would it work?
I'm
thinking 220v well pump, small transformer type welder, clothes dryer etc.

If it would work, would the two gen-sets need to be the same size?

There is probably some simple reason why this is a really bad idea, but I
don't have
enough electrical background to see it.

Thanks,

Bill

Bill Marrs wrote:
If a person had two small 110VAC generators. Ganged the commons and fed one
generator into each leg of a 220VAC single phase circuit, would it work?
I'm
thinking 220v well pump, small transformer type welder, clothes dryer etc.

If it would work, would the two gen-sets need to be the same size?

There is probably some simple reason why this is a really bad idea, but I
don't have
enough electrical background to see it.

Thanks,

Bill



First, it's good to think outside of the box. But not always.

I'd think you'd run into significant trouble in trying to get both
generators to be in phase with each other. I'd hazard if they aren't,
the one leading in phase will be feeding the other.

On Mon, 17 Sep 2007 18:38:38 GMT, Bill Marrs wrote:
If a person had two small 110VAC generators. Ganged the commons and fed one
generator into each leg of a 220VAC single phase circuit, would it work?

no

I'm thinking 220v well pump, small transformer type welder, clothes
dryer etc.

If it would work, would the two gen-sets need to be the same size?

There is probably some simple reason why this is a really bad idea,
but I don't have enough electrical background to see it.

Consider carefully what will happen if one spins at 61 Hz, and another
at 59 Hz

i

Bill Marrs wrote:

If a person had two small 110VAC generators. Ganged the commons and fed one
generator into each leg of a 220VAC single phase circuit, would it work?
I'm
thinking 220v well pump, small transformer type welder, clothes dryer etc.

If it would work, would the two gen-sets need to be the same size?

There is probably some simple reason why this is a really bad idea, but I
don't have
enough electrical background to see it.

Thanks,

Bill

Definitely won't work connected as you indicate, for the reasons other
posters noted.

It is possible to parallel two small gensets, and in this case you'd
need to feed a suitably sized step up transformer if you needed 240V.
There was an extensive thread on paralleling generators a week or two
ago on alt.energy.homepower presumably you can find archives of it.

On Mon, 17 Sep 2007 18:38:38 GMT, "Bill Marrs"
wrote:

If a person had two small 110VAC generators. Ganged the commons and fed one
generator into each leg of a 220VAC single phase circuit, would it work?
I'm
thinking 220v well pump, small transformer type welder, clothes dryer etc.

If it would work, would the two gen-sets need to be the same size?

There is probably some simple reason why this is a really bad idea, but I
don't have
enough electrical background to see it.

Thanks,

Bill


No way to synch the phases between the two...

gil fired this volley in
:

On Mon, 17 Sep 2007 18:38:38 GMT, "Bill Marrs"
wrote:

If a person had two small 110VAC generators. Ganged the commons and
fed one generator into each leg of a 220VAC single phase circuit,
would it work? I'm
thinking 220v well pump, small transformer type welder, clothes dryer
etc.

If it would work, would the two gen-sets need to be the same size?

There is probably some simple reason why this is a really bad idea,
but I don't have
enough electrical background to see it.

Thanks,

Bill


No way to synch the phases between the two...


Well... there is a way. Couple the two shafts, so the gensets run in
tandem. There's nothing written that says two gasoline engines cannot
power the same shaft.

This would require that you establish the phase positions of each set
before locking the shaft coupling, and it would also assume that the
machines are not of the "writable stator" variety. Only very expensive
units with frequency control would have that feature anyway.

It would probably also mean running both in the same direction, so
something akin to cogged belt drive between the shafts would be more
appropriate than just linking them up head to head.

All in all, this would be a major project -- no time in my life for that
sort of cobbling.

LLoyd

On Sep 17, 11:38 am, "Bill Marrs" wrote:
If a person had two small 110VAC generators. Ganged the commons and fed one
generator into each leg of a 220VAC single phase circuit, would it work?
I'm
thinking 220v well pump, small transformer type welder, clothes dryer etc.

If it would work, would the two gen-sets need to be the same size?

There is probably some simple reason why this is a really bad idea, but I
don't have
enough electrical background to see it.

Thanks,

Bill

Bill.
What the others have written is true. However, if you are buying new
generators, look at the ones for RV type use that are actually
generators that run solid state inverters that allow two to be
connected together. One as master, the other as slave. The electronics
are connected by cable to allow both to sync together and provide
combined power. And yes, they are the same size.

Paul

"Lloyd E. Sponenburgh" wrote:

gil fired this volley in
:

On Mon, 17 Sep 2007 18:38:38 GMT, "Bill Marrs"
wrote:

If a person had two small 110VAC generators. Ganged the commons and
fed one generator into each leg of a 220VAC single phase circuit,
would it work? I'm
thinking 220v well pump, small transformer type welder, clothes dryer
etc.

If it would work, would the two gen-sets need to be the same size?

There is probably some simple reason why this is a really bad idea,
but I don't have
enough electrical background to see it.

Thanks,

Bill


No way to synch the phases between the two...


Well... there is a way. Couple the two shafts, so the gensets run in
tandem. There's nothing written that says two gasoline engines cannot
power the same shaft.

This would require that you establish the phase positions of each set
before locking the shaft coupling, and it would also assume that the
machines are not of the "writable stator" variety. Only very expensive
units with frequency control would have that feature anyway.

It would probably also mean running both in the same direction, so
something akin to cogged belt drive between the shafts would be more
appropriate than just linking them up head to head.

All in all, this would be a major project -- no time in my life for that
sort of cobbling.

LLoyd

Isn't that more or less how those tractor pull loons stack engines?

wrote:

On Sep 17, 11:38 am, "Bill Marrs" wrote:
If a person had two small 110VAC generators. Ganged the commons and fed one
generator into each leg of a 220VAC single phase circuit, would it work?
I'm
thinking 220v well pump, small transformer type welder, clothes dryer etc.

If it would work, would the two gen-sets need to be the same size?

There is probably some simple reason why this is a really bad idea, but I
don't have
enough electrical background to see it.

Thanks,

Bill

Bill.
What the others have written is true. However, if you are buying new
generators, look at the ones for RV type use that are actually
generators that run solid state inverters that allow two to be
connected together. One as master, the other as slave. The electronics
are connected by cable to allow both to sync together and provide
combined power. And yes, they are the same size.

Paul

The Honda EU series and also Yamaha equivalents. Actually the only
connection between them is paralleling the outputs. There is a
perception that because you are supposed to use a special paralleling
cable set, there are some control signals on it, but that is not the
case.

If you look at the schematics, the parallel cable connections directly
connect to the inverter output. The reason for the special cable set is
simply safety - the shrouded banana plugs prevent you from potentially
contacting the live output connections if you plug / unplug them.

A "suicide" cable with two regular 5-15 plugs will work properly, but
presents the safety hazard potential to have a live male plug. Many
people operate them this way to save a buck over buying the parallel
cable kit. Many smarter people order shrouded banana plugs and make
their own safety parallel cable set to save a buck.

Of course you still have the issue of 240V, since these are 120V
generators. You'd need a step-up transformer if you really needed 240V.

Pete C.

In spite of what the others have said about synchronizing things, in
theory it can be done. In practice, with small generators, NOT A CHANCE!

consider: first unit is running at full speed and half power into a
load. Disconnect the field windings on the second unit, bring it up to
speed, match the speeds as precisely as you can. Slowly bring the field
current. If (when) the 2nd unit is going a bit too slow, generator #2
will act like a motor and try to speed up engine #2. And the additional
load on generator #1 will tend to slow that engine down. Similarly, if
#2 is too fast, it will act like a generator and slow down engine #2,
etc etc. Bringing the field current up slowly will allow the units to
find a compromise condition where both are putting full power into the
load. The power company does this all the time for their generators.

In practice, the governors on these units are way to unstable (about 2
orders of magnitude!) to keep the synchronizing currents within
reasonable bounds. You will blow the breaker almost instantly.

Bill Marrs wrote:
If a person had two small 110VAC generators. Ganged the commons and fed one
generator into each leg of a 220VAC single phase circuit, would it work?
I'm
thinking 220v well pump, small transformer type welder, clothes dryer etc.

If it would work, would the two gen-sets need to be the same size?

There is probably some simple reason why this is a really bad idea, but I
don't have
enough electrical background to see it.

Thanks,

Bill

"Pete C." wrote in message
...
wrote:

If you look at the schematics, the parallel cable connections directly
connect to the inverter output. The reason for the special cable set is
simply safety - the shrouded banana plugs prevent you from potentially
contacting the live output connections if you plug / unplug them.

A "suicide" cable with two regular 5-15 plugs will work properly, but
presents the safety hazard potential to have a live male plug. Many
people operate them this way to save a buck over buying the parallel
cable kit. Many smarter people order shrouded banana plugs and make
their own safety parallel cable set to save a buck.

Of course you still have the issue of 240V, since these are 120V
generators. You'd need a step-up transformer if you really needed 240V.

OK---I've got the part about phase syncronization, and understand that as a
practical
source of 240VAC there are some real problems, but I'm still not getting the
part about
needing a step-up transformer.

240VAC Single Phase is 2 120v legs and a common. Either leg to ground is
120v,
and leg to leg is 240v. We aren't talking 3 phase here.

SO why wouldn't two synchronized generators be a source of 240v single
phase?

Bill

"Bill Marrs" wrote:



OK---I've got the part about phase syncronization, and understand that as a
practical
source of 240VAC there are some real problems, but I'm still not getting the
part about
needing a step-up transformer.

240VAC Single Phase is 2 120v legs and a common. Either leg to ground is
120v,
and leg to leg is 240v. We aren't talking 3 phase here.

SO why wouldn't two synchronized generators be a source of 240v single
phase?

A: Because they still won't be synchronized, unless you parallel the
outputs.
and
B: If they were synchronized, you would get 120 from either hot to
neutral, and 0 V from Hot to Hot. You need to have them synchronized
AND 180 deg out to get 240 Hot to Hot, and that aint going to happen
(easily)

jk

"jk" wrote in message
...
"Bill Marrs" wrote:



OK---I've got the part about phase syncronization, and understand that as
a
practical
source of 240VAC there are some real problems, but I'm still not getting
the
part about
needing a step-up transformer.

240VAC Single Phase is 2 120v legs and a common. Either leg to ground is
120v,
and leg to leg is 240v. We aren't talking 3 phase here.

SO why wouldn't two synchronized generators be a source of 240v single
phase?

A: Because they still won't be synchronized, unless you parallel the
outputs.
and
B: If they were synchronized, you would get 120 from either hot to
neutral, and 0 V from Hot to Hot. You need to have them synchronized
AND 180 deg out to get 240 Hot to Hot, and that aint going to happen
(easily)

jk

Well heck----If it was easy everybody would be doing it! I think I'll shut
up
and go do something I understand. Time to make some chips.

Bill

RoyJ wrote:

In spite of what the others have said about synchronizing things, in
theory it can be done. In practice, with small generators, NOT A CHANCE!

consider: first unit is running at full speed and half power into a
load. Disconnect the field windings on the second unit, bring it up to
speed, match the speeds as precisely as you can. Slowly bring the field
current. If (when) the 2nd unit is going a bit too slow, generator #2
will act like a motor and try to speed up engine #2. And the additional
load on generator #1 will tend to slow that engine down. Similarly, if
#2 is too fast, it will act like a generator and slow down engine #2,
etc etc. Bringing the field current up slowly will allow the units to
find a compromise condition where both are putting full power into the
load. The power company does this all the time for their generators.

In practice, the governors on these units are way to unstable (about 2
orders of magnitude!) to keep the synchronizing currents within
reasonable bounds. You will blow the breaker almost instantly.


It can indeed be done, and the low rotating mass of the small generators
actually makes it easier to do and more tolerant of phase mismatch on
sync-up. Go read the thread on alt.energy.homepower I referenced,
particularly the posts from Neon John, a credible poster who parallels
two $100 Chinese generators to run an A/C unit for his semi.

The best way is drive a 120V to 220 V CT transformer.
Martin

Martin H. Eastburn
@ home at Lions' Lair with our computer lionslair at consolidated dot net
TSRA, Life; NRA LOH & Patron Member, Golden Eagle, Patriot's Medal.
NRA Second Amendment Task Force Charter Founder
IHMSA and NRA Metallic Silhouette maker & member.
http://lufkinced.com/


Lloyd E. Sponenburgh wrote:
gil fired this volley in
:

On Mon, 17 Sep 2007 18:38:38 GMT, "Bill Marrs"
wrote:

If a person had two small 110VAC generators. Ganged the commons and
fed one generator into each leg of a 220VAC single phase circuit,
would it work? I'm
thinking 220v well pump, small transformer type welder, clothes dryer
etc.

If it would work, would the two gen-sets need to be the same size?

There is probably some simple reason why this is a really bad idea,
but I don't have
enough electrical background to see it.

Thanks,

Bill

No way to synch the phases between the two...


Well... there is a way. Couple the two shafts, so the gensets run in
tandem. There's nothing written that says two gasoline engines cannot
power the same shaft.

This would require that you establish the phase positions of each set
before locking the shaft coupling, and it would also assume that the
machines are not of the "writable stator" variety. Only very expensive
units with frequency control would have that feature anyway.

It would probably also mean running both in the same direction, so
something akin to cogged belt drive between the shafts would be more
appropriate than just linking them up head to head.

All in all, this would be a major project -- no time in my life for that
sort of cobbling.

LLoyd

----== Posted via Newsfeeds.Com - Unlimited-Unrestricted-Secure Usenet News==----
http://www.newsfeeds.com The #1 Newsgroup Service in the World! 120,000+ Newsgroups
----= East and West-Coast Server Farms - Total Privacy via Encryption =----

Pete C. wrote:
RoyJ wrote:
It can indeed be done, and the low rotating mass of the small generators
actually makes it easier to do and more tolerant of phase mismatch on
sync-up. Go read the thread on alt.energy.homepower I referenced,
particularly the posts from Neon John, a credible poster who parallels
two $100 Chinese generators to run an A/C unit for his semi.

Look for the thread "parallel generators"

Honda inverter generatorss can be synchronized via a special cable. It
is a very special application, not applicable to the general case.

i

On Mon, 17 Sep 2007 14:33:20 -0500, with neither quill nor qualm,
Ignoramus26157 quickly quoth:

On Mon, 17 Sep 2007 18:38:38 GMT, Bill Marrs wrote:
If a person had two small 110VAC generators. Ganged the commons and fed one
generator into each leg of a 220VAC single phase circuit, would it work?

no

I'm thinking 220v well pump, small transformer type welder, clothes
dryer etc.

If it would work, would the two gen-sets need to be the same size?

There is probably some simple reason why this is a really bad idea,
but I don't have enough electrical background to see it.

Consider carefully what will happen if one spins at 61 Hz, and another
at 59 Hz

It won't sound nearly as bad as those out-of-sync engines in the old
Flying Fortresses or Liberators going over the house back when they
were used for fighting fires. (I missed WWII.)

--

According to our strength of character and our clarity of vision, we will
endure, we will succeed, we will have contributed something to make life
where we were and as we lived it better, brighter, and more beautiful.
-- Frank Lloyd Wright

When I was in school, we synchronized a generator with the utility power by
connecting a light bulb between them. When the bulb went out, they were in
phase, and we threw the switch. After that, they were self-synchronizing,
because if our generator slowed down, it would start to draw power from the
line, and come back to speed.

But synchronizing two generators in SERIES (instead of parallel) is a whole
nother thing.

Someone asked why you need a X-former. Kuz, if you're running two 120 v
generators in parallel, you getg 120 volts. The transformer gets you up to
240. The OP asked about a way to get 240v out of two generators. He didn't
say he needed two generators to get the required wattage. ONE generator and
a X-former would do it if the power is high enough to run the load.

Take a look at the geneerator panel--Many or most of them have a 240 volt
output, in which case you won't even need the X-former.

On Tue, 18 Sep 2007 06:47:23 GMT, "Leo Lichtman"
wrote:

When I was in school, we synchronized a generator with the utility power by
connecting a light bulb between them. When the bulb went out, they were in
phase, and we threw the switch.
SNIP

Hey Leo,

Old "Preston Chronicle" newspaper report:

--------The cause of death was trauma caused by exploding machinery
when the new plant operator threw the switch to connect the building
generator to the incoming supply. In his previous place of
employment, they had used a "lamp out" system, while this plant used a
"bright light" system to detect phase synchronization.------

And the same is possible if the "lamp" burns out at just the wrong
time, as it is prone to do with the voltage fluctuations during
run-up. Bright-light is not as sensitive, but somewhat safer.

Take care.

Brian Lawson,
Bothwell, Ontario.

Ignoramus26157 wrote:

Honda inverter generatorss can be synchronized via a special cable. It
is a very special application, not applicable to the general case.

i

It's not really a special cable Iggy, it just parallels the inverter
output connections. The only thing special is that it uses shrouded
banana plugs so you don't have the potential for live exposed connector
pins if a cable is unplugged. Using a "suicide" Y cable with two regular
5-15 male plugs works just fine, but has the potential for the live
exposed male pin safety hazard. Of course the inverters in the Hondas
are designed to sync with external sources.

As for paralleling small non inverter generators, it can be done. Check
the "paralleling generators" thread on alt.energy.homepower for info.

On Tue, 18 Sep 2007 06:45:42 -0500, Pete C. wrote:
Ignoramus26157 wrote:

Honda inverter generatorss can be synchronized via a special cable. It
is a very special application, not applicable to the general case.

i

It's not really a special cable Iggy, it just parallels the inverter
output connections. The only thing special is that it uses shrouded
banana plugs so you don't have the potential for live exposed connector
pins if a cable is unplugged. Using a "suicide" Y cable with two regular
5-15 male plugs works just fine, but has the potential for the live
exposed male pin safety hazard. Of course the inverters in the Hondas
are designed to sync with external sources.

As for paralleling small non inverter generators, it can be done. Check
the "paralleling generators" thread on alt.energy.homepower for info.

I thought that it was a special cable, that commanded inverters to
work in sync.

i

In article ,
Brian Lawson wrote:

On Tue, 18 Sep 2007 06:47:23 GMT, "Leo Lichtman"
wrote:

When I was in school, we synchronized a generator with the utility power by
connecting a light bulb between them. When the bulb went out, they were in
phase, and we threw the switch.
SNIP

Hey Leo,

Old "Preston Chronicle" newspaper report:

--------The cause of death was trauma caused by exploding machinery
when the new plant operator threw the switch to connect the building
generator to the incoming supply. In his previous place of
employment, they had used a "lamp out" system, while this plant used a
"bright light" system to detect phase synchronization.------

And the same is possible if the "lamp" burns out at just the wrong
time, as it is prone to do with the voltage fluctuations during
run-up. Bright-light is not as sensitive, but somewhat safer.

Use two lamps, one "lamp on" (in a green globe), the other "lamp out"
(and in a red globe)?

Joe Gwinn

Regarding a danger of backfeeding a generator, I have a question.

What if the generator has a circuit breaker? So the backfeeding power
goes in through a breaker? Would the breaker save the generator from
backfeeding damage, in this instance? (assuming properly sized
breaker)

thanks

i

Leo Lichtman wrote:
When I was in school, we synchronized a generator with the utility power by
connecting a light bulb between them. When the bulb went out, they were in
phase, and we threw the switch. After that, they were self-synchronizing,
because if our generator slowed down, it would start to draw power from the
line, and come back to speed.

That brings back memories. In the airforce at a radar site we had 3
big Buda (sp?) geneators which when used to operate the set had to
be synched. There was the same light bulb on the control pannel and
when it went out the switch was thrown to connect the second one.
Ah yes 1952 boy was that a long time ago.
...lew...

Brian Lawson wrote:

And the same is possible if the "lamp" burns out at just the wrong
time, as it is prone to do with the voltage fluctuations during
run-up. Bright-light is not as sensitive, but somewhat safer.

Brian Lawson,
Bothwell, Ontario.
I think anyone who would mistake the "burn out" of a lamp for the
way the lamp responds to the phase matching of the generators
should not be in the position of being alowed to do it. :-)
...lew...

Joseph Gwinn wrote:
And the same is possible if the "lamp" burns out at just the wrong
time, as it is prone to do with the voltage fluctuations during
run-up. Bright-light is not as sensitive, but somewhat safer.


Use two lamps, one "lamp on" (in a green globe), the other "lamp out"
(and in a red globe)?

Joe Gwinn
Joe there is a saying something about making it Idiot proof and
what happens along comes a biger Idiot. :-)
...lew...

Ignoramus3635 wrote:

On Tue, 18 Sep 2007 06:45:42 -0500, Pete C. wrote:
Ignoramus26157 wrote:

Honda inverter generatorss can be synchronized via a special cable. It
is a very special application, not applicable to the general case.

i

It's not really a special cable Iggy, it just parallels the inverter
output connections. The only thing special is that it uses shrouded
banana plugs so you don't have the potential for live exposed connector
pins if a cable is unplugged. Using a "suicide" Y cable with two regular
5-15 male plugs works just fine, but has the potential for the live
exposed male pin safety hazard. Of course the inverters in the Hondas
are designed to sync with external sources.

As for paralleling small non inverter generators, it can be done. Check
the "paralleling generators" thread on alt.energy.homepower for info.

I thought that it was a special cable, that commanded inverters to
work in sync.

i

Nope, just direct connection to the inverter output. Strictly an
electrical safety issue.

Ignoramus29233 wrote:
Regarding a danger of backfeeding a generator, I have a question.

What if the generator has a circuit breaker? So the backfeeding power
goes in through a breaker? Would the breaker save the generator from
backfeeding damage, in this instance? (assuming properly sized
breaker)

Regarding Brian's article, there's no date so we
don't know the vintage of the electrical equipment.
Circuit breakers, especially in the old days,
depended on a minimal amount of resistance and
inductance between them and the source. They are
also limited as to the absolute maximum surge
current.

I can't think of a worse situation than strapping
together the two busbars of generators exactly
180 out of phase. You'd be producing a fault
current twice that of a hard short circuit. If
everything were sized for that, it's no surprise
something exploded.

Joseph Gwinn wrote:

And the same is possible if the "lamp" burns out at just the wrong
time, as it is prone to do with the voltage fluctuations during
run-up. Bright-light is not as sensitive, but somewhat safer.

Use two lamps, one "lamp on" (in a green globe), the other "lamp out"
(and in a red globe)?

Never seen a "bright light" system.
Every power plant I have ever been in, that had idiot lights, had
lights that were out when in sync. All but a couple also had
synchroscopes.
jk

Ignoramus29233 wrote:

Regarding a danger of backfeeding a generator, I have a question.

What if the generator has a circuit breaker? So the backfeeding power
goes in through a breaker? Would the breaker save the generator from
backfeeding damage, in this instance? (assuming properly sized
breaker)


Yes , no and perhaps.

A breaker can not (by itself) sense that the power flow is reverse. So
if the reverse flow isn't large, then NO.

If the flow is large, so that the current exceeds breaker rating, then
perhaps.
If the flow is large, then yes.
If even larger, then again perhaps not.

TYpical rule of thumb in protection for piston (Turbines are a
different animal) engines (large) against reverse power, is 15%-25% of
rating, for a time period from seconds to minutes. But that requires a
reverse power relay.

Still won't protect you against twisting or snapping your shaft.

jk

Jim Stewart wrote:

I can't think of a worse situation than strapping
together the two busbars of generators exactly
180 out of phase. You'd be producing a fault
current twice that of a hard short circuit. If
everything were sized for that, it's no surprise
something exploded.


I can, and thats closing in one generator to a stiff system, 180 out.
You still produce a fault 2x that of the 3phse bolted fault, but that
starts out as a larger number in the stiff system case.
jk

On Tue, 18 Sep 2007 10:11:28 -0700, Jim Stewart
wrote:

Ignoramus29233 wrote:
Regarding a danger of backfeeding a generator, I have a question.

What if the generator has a circuit breaker? So the backfeeding power
goes in through a breaker? Would the breaker save the generator from
backfeeding damage, in this instance? (assuming properly sized
breaker)

Regarding Brian's article, there's no date so we
don't know the vintage of the electrical equipment.
Circuit breakers, especially in the old days,
depended on a minimal amount of resistance and
inductance between them and the source. They are
also limited as to the absolute maximum surge
current.

I can't think of a worse situation than strapping
together the two busbars of generators exactly
180 out of phase. You'd be producing a fault
current twice that of a hard short circuit. If
everything were sized for that, it's no surprise
something exploded.


On all the multi generator sets I have seen the generator connects to
a circuit breaker and then to the bus. The circuit breaker is what you
turn on when the frequencies are in phase.


Bruce in Bangkok
(brucepaigeATgmailDOTcom)

On Tue, 18 Sep 2007 12:59:35 -0700, jk wrote:

Jim Stewart wrote:

I can't think of a worse situation than strapping
together the two busbars of generators exactly
180 out of phase. You'd be producing a fault
current twice that of a hard short circuit. If
everything were sized for that, it's no surprise
something exploded.


I can, and thats closing in one generator to a stiff system, 180 out.
You still produce a fault 2x that of the 3phse bolted fault, but that
starts out as a larger number in the stiff system case.
jk

It would depend on the sub-synchronous reactance of the alternator, not the
synchronous reactance. The fault current would be no larger than that which
occurred with a pole-slip and a normal generator will survive that. The
operators, might need to do some laundry before appearing in public, but the
alternator should suffer no major damage.


Mark Rand
RTFM