[RE-wrenches] PSX-240 wiring question

[dan at foxfire-energy.com]

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_______________________________________________
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