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Stacking or Paralleling Inverters????

J

J Poy

Jan 1, 1970
0
I have 2 small Xpower Plus 400W inverters (Xantrex) and I would like to
connect them in parallel to increase the overall power output. 4+4= 800W.

I call Xantrex the manufacturer and the customer service technical support
said it could not be done. They refused to connect me to the engineering
dept. when I ask for a schematic diagram.

Has anyone been successful in stacking two of these inverters or knows where
I can get schematic drawing.

Things I have thought of:

.... Output voltage must be in phase both units. How you ask by using the
same sync pulses to drive both inverters. Next question would be is the sync
pulse for one unit be capable of driving to inverters?

.... Could output load balancing be problem? I am not sure?

I am sure there could be more problems.

Any suggestions where I can get some information on this subject? Please and
Thank You.

Jim
 
R

Rich Grise

Jan 1, 1970
0
J said:
I have 2 small Xpower Plus 400W inverters (Xantrex) and I would like to
connect them in parallel to increase the overall power output. 4+4= 800W.

I call Xantrex the manufacturer and the customer service technical support
said it could not be done. They refused to connect me to the engineering
dept. when I ask for a schematic diagram.

Has anyone been successful in stacking two of these inverters or knows
where I can get schematic drawing.

Things I have thought of:

... Output voltage must be in phase both units. How you ask by using the
same sync pulses to drive both inverters. Next question would be is the
sync pulse for one unit be capable of driving to inverters?

... Could output load balancing be problem? I am not sure?

I am sure there could be more problems.

Any suggestions where I can get some information on this subject? Please
and Thank You.

Jim

I've seen inverters in parallel, and yes, they simply used the same
sync line. But they were designed to work that way. I'd be very careful
if I were going to hack a couple of commercial units.

Of course, it will void the warranty. They didn't want to talk to you
because of the liability problems if they let you even _think_ they'd
approve such an arrangement.

Open the units, take a look, and if you have the electronics background
to do it safely, then do it, otherwise, leave them intact, sell them,
and buy a bigger unit. If they have "Warranty Void if This Sticker is
Removed" stickers, then be aware that they're extremely difficult to
remove without it showing.

Good Luck!
Rich
 
R

repatch

Jan 1, 1970
0
Don't even bother THINKING about doing something like this. Buy a bigger
inverter.

On Thu, 29 Jul
 
D

Dan Fraser

Jan 1, 1970
0
I agree. If you don't know why this is impractical except for a very
experienced engineer, you can't do it. However, the services of an
experienced engineer, like myself will cost more than a bigger inverter.
 
J

jriegle

Jan 1, 1970
0
If you don't care about hosing the inverters, why not try?
If you could tap the clock output on one, disable the clock on the other and
bring the signal over, It could possibly work.
As you say, phasing could be an issue. The clock signal may be high since
many things go on inside the inverter in a nornal 60 Hz cycle. Some units
adjust the output pulse width for regulation. getting all this in sync could
be a problem.
John
 
C

Checkmate

Jan 1, 1970
0
On Thu, 29 Jul 2004 14:51:49 -0400, J Poy put forth the notion that...

I have 2 small Xpower Plus 400W inverters (Xantrex) and I would like to
connect them in parallel to increase the overall power output. 4+4= 800W.

I call Xantrex the manufacturer and the customer service technical support
said it could not be done. They refused to connect me to the engineering
dept. when I ask for a schematic diagram.

Has anyone been successful in stacking two of these inverters or knows where
I can get schematic drawing.

Things I have thought of:

... Output voltage must be in phase both units. How you ask by using the
same sync pulses to drive both inverters. Next question would be is the sync
pulse for one unit be capable of driving to inverters?

... Could output load balancing be problem? I am not sure?

I am sure there could be more problems.

Any suggestions where I can get some information on this subject? Please and
Thank You.

Jim

The solution is simple... sell the two 400 watt units, and buy an 800
watt unit. You're not going to be able to get two of them to stay in
sync.
 
B

bushbadee

Jan 1, 1970
0
We did it all the time at Electro Solids corp.
But our inverters had inputs for syncing them together.
If you want to do that, get inverters with syncing ability.
But unless the converters are short circuit protected with the voltage
falling off into a short rather than just turning off do not parrelel
converts.

What will happen when you parrellel converters is the one with the hightest
output voltage will carry as much of the load as it can and then go into
overload so the voltage will fall till it matches the output voltage of the
one in over load and then it will take up the remainder of the load.

If the two converters are synced, it is better to put the outputs in series
with each supplying 1/2 the load. voltage.
You can put both in series and use a step down tranformer to accomplish the
same thing.

But in general, I would say, if you have to ask, you should not do it as you
just do not understand what is involved.
 
B

bushbadee

Jan 1, 1970
0
Checkmate said:
On Thu, 29 Jul 2004 14:51:49 -0400, J Poy put forth the notion that...



The solution is simple... sell the two 400 watt units, and buy an 800
watt unit. You're not going to be able to get two of them to stay in
sync.

We did it all the time at ElectoSolids Corp.
 
A

Alan Stiver, PE

Jan 1, 1970
0
But, as you said in your earlier post, your units were made to do that.
This is just not a do-it-yourself, hobbyist undertaking. Without the
proper experience (doesn't have it), full schematics (doesn't have
them), lots of test equipment (meters, scopes, etc. - if he has all
that, he should be able to afford an 800kva inverter, they're a lot less
expensive than a trip to the emergency room), and more than a little
careless disregard for safety (both his and whoever winds up using this
contraption), this is better left alone.

Al
 
B

bushbadee

Jan 1, 1970
0
I agree with you completely.
And I basically so stated.
I just told him that it could be done and that it has been done.

But I also said and have often said this, if you have to ask how to do it,
then you shouldn't try to do it.

When fooling around with 400 and 800 va inverters which can give you a quick
trip to the cemetary, that holds double true.
 
J

Jimmie

Jan 1, 1970
0
bushbadee said:
I agree with you completely.
And I basically so stated.
I just told him that it could be done and that it has been done.

But I also said and have often said this, if you have to ask how to do it,
then you shouldn't try to do it.

When fooling around with 400 and 800 va inverters which can give you a quick
trip to the cemetary, that holds double true.

May be interesting to try. Take two inverters, I believe the ones in
question of the self excited type where all you have is a transformer and a
couple of transistors. Monitor them and when they get in phase through a
switch connecting them together and see if they lock or melt down. Probably
would be safe enough to try if they were connected together with a 2 amp
fuse for initial test.
 
A

Alan Stiver, PE

Jan 1, 1970
0
oops, I meant 800va, not 800kva.

Alan Stiver, PE wrote:
.... he should be able to afford an 800kva inverter, they're a lot less
 
J

J Poy

Jan 1, 1970
0
Hi everyone!

Thought I'd let you know what I decided to do:

.... Without a schematic well it's like going on a trip without a map, if you
know what I mean. You can get there but might take you along time. I hoping
someone might have a schematic of this inverter.
.... Your all right with regards to the dangers of trying to actually
parallel two of these inverters, but I really wanted to hear someone who
might have actually done this with these particular ones.
.... My background is in electronics, but as I see it why try to invent the
wheel if someone has already done it. I am not working on inverters per say,
but I do have a electronics degree and have study inverters in the past.
.... Yes I do have all the electronic (Scope, DVM, generators etc.) equipment
to perform the work safely to the inverters as well to me.

In the end I have decided to hold off for now and try to more research on
the subject.

Thank you all for your comments!

Jim
 
B

bushbadee

Jan 1, 1970
0
Real inverters is a very specialized subject that they do not teach in
Colleges.
The secrets were passed passed on to me by a German scientist.
 
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