RF from SMA 2500 U [RE-wrenches]

jberdner at sma-america.com jberdner at sma-america.com
Tue Sep 17 15:41:42 PDT 2002


Max:

The 2500U and 1800U both meet FCC part 15 requirements for both
commercial and residential use.  This means we should be better then the
average PC in the home.  We have seen two cases where the Sunny Boy
created some RFI interference.  

In one case the customer's computer room was directly inside the wall
where the inverters were mounted.  He had one older monitor (out of 4 in
the room) that had some lines on it.  Not terrible but definitely an
annoyance.  We tried a few things and he ultimately just bought a new
monitor - problem solved.   

In the other case we had a system with 1 Sunny Boy and 3 ST's.   That
combination made a horrible racket on his wife's favorite AM radio talk
show. We added a common mode choke to the dc input and ac output side of
the Sunny Boy which helped a great deal but did not eliminate the
problem.  When he switched out the 3 ST's to Sunny Boys he heard
"blessed silence".  After the swap out he removed the chokes from unit
#1 and everything was still ok.  Apparently there is a beat frequency
created between the two inverters that was causing the problem. Go
figure.

Please contact me offline so I can get some more information from you or
the customer about he warble - duration, frequency, how often it occurs,
etc. so I can try to figure out if it is the Sunny Boy or something else
in the system.  


Best Regards,

John Berdner

SMA America, Inc.
20830 Red Dog Road
Grass Valley, CA  95945
530.273.4595 (voice)
530.274.7271 (fax) 


-----Original Message-----
From: Max Balchowsky [mailto:max at seesolar.com] 
Sent: Tuesday, September 17, 2002 1:25 PM
To: RE-wrenches at topica.com
Subject: RF from SMA 2500 U [RE-wrenches]

Has anyone had this problem: Installed 7.2KW system, inverters on
opposite side of house from service disconnect. Home owners computer
system 10' from service in his home office. He tells me since we turned
the system on he now gets warble noise from time to time in his computer
systems speakers. The monitor for the system is next to the inverters
and runs across the roof under flashing to the CTs in the serv panel
near the computer system. I have a similar problem at home when I use my
cell phone near my computer.....
Any experience withj this or any ideas.......

Max

SEE Systems
Palm Springs, Ca. 92262
760-403-6810

[Non-text portions of this message have been removed]

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