600 VDC switches [RE-wrenches]

Mon Feb 10 18:36:36 PST 2003

Guys:

Yes, this is good news from Square D.
We have been working on this one for over a year.
Now that it has come to pass I want to jump in and take some credit.
I know it is shameless, but I can't resist - sorry ;-)

Many people were involved but Tom Keene at Square D deserves most of the
real credit.  He was a great champion for our industry inside Square D
and I do not think we could have done it without his support.

First we had John Wiles and SWTDI run some tests for us and, based on
John's data, it looked like the 361 could do 13 Amps. 
Then Marv used the results to develop and get UL approval on a whole new
test procedure specifically for PV system dc disconnects.  This was
bucking tradition and was a lot harder than it sounds.  Thanks to Tim Z.
at UL for the support on this one.

Then we had to get Square D to run the procedure that UL approved.
Then we had to get Square D to run it again since they ran the old
switch procedure by mistake and the switch did not pass the test that we
already knew it would not pass (90 Amps at 600 Vdc for 50 cycles then
2000 cycles at 30 amps and 600 Vdc).  
In the middle of all this Square D legal got involved and side tracked
the whole thing for about 3 months.  This snafu was why we stopped
recommending the HU361 for a couple of months.

Bottom Line - 1 switch can be the disconnect for up to 3 inverters.  One
more point - The lugs are UL approved for 2 wires in each lug!
The two positive strings can be combined in the switch with a single
positive going out of the switch to the inverter.  The two negatives
just pass through the switch uninpterrupted and land on 2 of 3 negative
terminals in the inverter. 

Now I am trying to get some UL documentation on the new ratings for the
switch from Square D.  Once we get it we will post it on our website or
tell you how to find it on Square D's.  The UL file reference in E.H.'s
post does not show the new ratings yet.

The next step is to get UL approval for a combination DC and AC
disconnect in the same switch.
1 pole for PV positve / polymeric divider for seperation of circuits / 2
poles for the 2 ac hots.  If we can get that, we have 1 disconnect that
is both the ac and dc disconnect and meets the utility requirements.
Keep your fingers crossed.

If you have any questions, or if I can be of any further assistance,
please do not hesitate to contact me.

Best Regards,

John Berdner

SMA America, Inc.
12438 Loma Rica Drive, Unit C
Grass Valley, CA  95945
530.273.4595 (voice)
530.274.7271 (fax) 

-----Original Message-----
From: Mangelsdorf, Marco [mailto:mmangelsdorf at hei.com] 
Sent: Monday, February 10, 2003 4:10 PM
To: RE-wrenches at topica.com
Subject: RE: 600 VDC switches [RE-wrenches]

Good news, indeed.  From what source can we get this bugger?  Will it be
immediately available?  

marco
ProVision Technologies
Hilo

Wrenches,

Good news from Square D on this thread. I found out today that Square D
has
received UL approval for use of the HU361 in PV systems up to 600VDC and
not
more than 13A per pole (no series switching or negative switching is
required - 3 poles, 3 positives). See letter from Square D below.

E. H. Roy
Solar Works, Inc.
64 Main Street
Montpelier, VT 05602
1-800-339-7804 ext. 306
ehroy at solar-works.com

	DATE:	2/10/03
	TO:	E. H. Roy - Solar-works, Inc
	FROM:	Bob Miller - Square D Company
	SUBJECT:	Photovoltaic application of Safety Switches

E.H.,

Square D Company has obtained UL listing (File E2875, Vol. 1) for 30 amp
non-fused heavy duty switches, HU361, HU361RB, HU361AWK and HU361DS,
for
use on photovoltaic systems. The 2002 National Electrical Code does not
allow the negative conductor to be broken when operating switches on
photovoltaic systems.  The above mentioned switches may be used on
photovoltaic systems as shown below as long as the line voltage per pole
does not exceed 600 Volts DC and the normal rated current per pole does
not
exceed 13 Amps DC.

Bob Miller
Application Engineer
Square D Company
859-243-8069

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