[RE-wrenches] Specific AC Coupling question

[jay]

HI Allan,

The only reason to frequency shift is for “softer” charging.
VRLA are not as sensitive to the pulse type charging that a relay type charging would do.  
And regardless if you have frequency shift or not, you will still need ( especially with VRLA) a high voltage relay.
I recommend a SS relay, but a regular mechanical contactor will do as well.

jay

Peltz Power.



> On Apr 4, 2016, at 12:34 PM, Allan Sindelar <allan at sindelarsolar.com> wrote:
> 
> Wrenches,
> Core question first: Will a ~2010 Fronius IG-4000 respond properly to the frequency shift regulation supplied by a new Schneider XW+5548 or XW+6848?
> 
> Situation: I haven't seen the Colorado site; I'm working as a consultant to produce an upgrade component list and will later serve as a resource during local installation of the upgrade equipment. Customer has hired me to turn a hodgepodge system into a GTBB system. The system has two key parts: an existing SW5548 with batteries, never properly installed (only AC1 in was ever connected to a main load center!) with 3.1 kW of tracker-mounted PV through an Outback FM60; and a roof-mounted 4kW array feeding the grid panel via the IG-4000. As currently installed, nothing will operate as wired during a grid outage, and a 240V AC well pump isn't supported.
> 
> The simple plan is to replace the SW5548 with an XW+5548 or 6848 with Midnite E-Panel; replace batteries with Surrette FLAs; keep existing arrays unchanged; use existing FM60 for smaller tracked array; use existing Fronius IG-4000 but AC couple it to the output of the XW. The customer understands that sell amperage is limited by the inverter (to 20A @ 240V for the 5548, or 4,800W, or 27A @ 240V for the 6848, or 6,480W) when the grid is up, but the full array can charge the battery bank when the grid is down.
> 
> Schneider tech support assures me that the XW+ is good in this application, but I need to get an OK from Fronius about frequency-shift compatibility. Fronius tech support tells me that it may or may not work: the 0.4 hz shift is within the the normal frequency tolerance for this model. While the tolerance window may be tightened up in the field, such tightening may cause nuisance tripping, especially with reactive loads like a well pump or A/C. The tech suggested that we first test the frequency-shift approach, and add a DC-coil contactor between the output of the Fronius and the XW+ if it doesn't.
> 
> Has anyone AC coupled these two units? Did it work? Any unexpected problems? Did you add a voltage-controlled contactor? What should I advise my client?
> Thank you,
> Allan
> -- 
> Allan Sindelar
>  <mailto:allan at sindelarsolar.com>allan at sindelarsolar.com <mailto:allan at sindelarsolar.com>
> NABCEP Certified PV Installation Professional
> NABCEP Certified Technical Sales Professional
> New Mexico EE98J Journeyman Electrician
> Founder (Retired), Positive Energy, Inc.
> 505 780-2738 cell
> 
>  
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