[RE-wrenches] PSX-240 wiring question

Sat Sep 7 13:22:08 PDT 2013

I've got a similar situation with an old SW-4024. The house is wired
entirely for 120vac and is still an off-grid home but at some point the new
owners received grid power which they want to use as a back-up. They also
want to add a back-up 240vac genny. At first I thought of doing as Dan
suggest, using two X240's. But as I mulled over the design I decided to use
a single manual transfer switch and one X240. The transfer switch is 1/2 the
price of the 2nd PSX240. Thus on the primary of the transfer switch will be
either the grid or genny with the secondary side of the switch to be the
PSX240. I'm doing the upgrade next week.

Christopher

-----Original Message-----
From: re-wrenches-bounces at lists.re-wrenches.org
[mailto:re-wrenches-bounces at lists.re-wrenches.org] On Behalf Of
dan at foxfire-energy.com
Sent: Saturday, September 07, 2013 16:00
To: Allan at positiveenergysolar.com; RE-wrenches
Subject: Re: [RE-wrenches] PSX-240 wiring question

I'd just launder the tool thru the sw wid another X240 on its own switch. db

-------- Original Message --------
Subject: [RE-wrenches] PSX-240 wiring question
From: "Allan Sindelar" <allan at positiveenergysolar.com>
Date: Sat, September 7, 2013 2:56 pm
To: "RE-wrenches" <re-wrenches at lists.re-wrenches.org>

Wrenches,
 Here's a small issue on which I need help. It concerns the best functional
way to wire up an Outback PSX-240 balancing autotransformer for a specific
purpose.

 I have somehow succeeded in transferring the wiring diagram on page 6 of
Outback's PSX-240 installation manual into this message. This is for a
step-down/generator balancing function. 

 The situation: 8kW 240V AC generator serving an older system with a single
Trace SW4024. The 240V from the generator enters the PSX240 as wired
according to the diagram. The primary role of the generator is to provide
occasional backup charging to the batteries through the inverter. The
specific issue is that the client also wants 240V AC from the generator to
be available to a single shop receptacle to run a stationary woodworking
tool. The generator is not large enough to both run the tool and charge at
full (33A @120V AC / 120A @24V DC) AC2 amps in setting, and we don't want to
reduce the charge rate, as it's currently ideal for the new HUP industrial
flooded batteries.

 We initially tapped 240V off of the generator feed ahead of the 25A
two-pole breaker in the PSX-240. We instructed the customer to turn off this
25A breaker when using the power tool (the tool circuit has its own separate
two-pole breaker). What we discovered, which is obvious in hindsight, is
that one of the generator's 120V AC legs continues to feed the inverter AC2
input with the breaker off. This causes the inverter to try to draw too much
current from that AC generator leg only.

 My question: could I solve this by simply moving the "120VAC to Neutral"
output feed (now tapped off of L2) shown on the drawing below to the other
side of the 25A circuit breaker; that is, to point 4 in the drawing? It
seems to me that this would work, and would not intrinsically overload
either of the two 25A poles of the breaker. The 120V AC output to the
inverter could in theory draw 50A; 25A from L2 and 25A through the windings
of the transformer. But this solution seems almost too simple. What am I
missing, please?

 -- 
          Allan Sindelar
 Allan at positiveenergysolar.com
 NABCEP Certified PV Installation Professional  NABCEP Certified Technical
Sales Professional  New Mexico EE98J Journeyman Electrician  Founder and
Chief Technology Officer  Positive Energy, Inc., a Certified B CorporationTM
 3209 Richards Lane
 Santa Fe, New Mexico 87507
 505 424-1112 office 780-2738 cell
 www.positiveenergysolar.com_______________________________________________
List sponsored by Home Power magazine

List Address: RE-wrenches at lists.re-wrenches.org

Change email address & settings:
http://lists.re-wrenches.org/options.cgi/re-wrenches-re-wrenches.org

List-Archive:
http://lists.re-wrenches.org/pipermail/re-wrenches-re-wrenches.org

List rules & etiquette:
www.re-wrenches.org/etiquette.htm

Check out participant bios:
www.members.re-wrenches.org

_______________________________________________
List sponsored by Home Power magazine

List Address: RE-wrenches at lists.re-wrenches.org

Change email address & settings:
http://lists.re-wrenches.org/options.cgi/re-wrenches-re-wrenches.org

List-Archive:
http://lists.re-wrenches.org/pipermail/re-wrenches-re-wrenches.org

List rules & etiquette:
www.re-wrenches.org/etiquette.htm

Check out participant bios:
www.members.re-wrenches.org