600 VDC switches [RE-wrenches]

[Bill Brooks]

Brad,

Oops. I read off the wrong number. The disconnect was actually tested at 18
amps for absolute worst case conditions. I'm not sure why 18 amps was picked
to do the test but John B. could probably tell us. Perhaps for worst case
cloud enhancement on a 13-amp circuit.

The arguement of sustained 1250 W/m2 does not hold water for the code. We
assume that level as continuous worst case regardless. That way we are never
wrong. Cloud and snow enhancements can get us up to 1500 W/m2 for brief
periods.

I guess it depends on your view of the world whether 2 sets of 165s can be
run through a single pole. Otherwise, use them on two separate poles and
combine on the bottom side of the disconnect and call it a day.

Certainly appears marginal.

Bill.


-----Original Message-----
From: Brad Bassett [mailto:bsbassett at earthlink.net]
Sent: Thursday, February 13, 2003 12:34 PM
To: RE-wrenches at topica.com
Subject: SPAM: RE: RE: 600 VDC switches [RE-wrenches]


Bill, the Isc is 5.46A, so 5.46 x 2 x 1.25 = 13.65A

4.77A is the Imp. I think designing to Imp might be more realistic
though. Or take the PV 1.25 off the Isc. I've never seen Isc x 1.25
continuously (3 hours).

Brad



Bill Brooks wrote:
> Brad,
>
> I'm not sure that this question got answered. John Berdner probably
> knows
> better than I, but my understanding is that 13A is a continuous rating.
> The
> issue with a disconnect is what happens when it opens anyway, so it is a
> bit
> different than wire. However--the proper way to size is based on 690.8
> which
> says you take the total Isc of parallel strings and multiply by 1.25.
> The
> Isc of the 165-Watt module is 4.77 amps so max current is 12 amps (4.77A
> x 2
> x 1.25 = 11.925).
>
> Some bright guy must have picked that 13 amp number.
>
> Bill.
>
>
> -----Original Message-----
> From: Brad Bassett [mailto:bsbassett at earthlink.net]
> Sent: Wednesday, February 12, 2003 9:18 AM
> To: RE-wrenches at topica.com
> Subject: SPAM: RE: 600 VDC switches [RE-wrenches]
>
>
> John,
>
> I have not seen an answer to this question. If you feed an SB with two
> strings of modules, the 13A limit is likely to be exceeded if it is not
> rated for continuous. With the 165's it's exceeded even at PV 125%.
>
> Thanks,
> Brad
>
>
> William Miller wrote:
> > The rating is for 13 amps per pole.  Is this de rated for continuous, or
> > for PV?
> >
> > Thanks again,
> >
> > William
> >
> >
>
>
>
>
> Brad Bassett
> Schott Applied Power
> Tumwater, WA office
> bsbassett at earthlink.net
>
> - - - -
> To send a message: RE-wrenches at topica.com
>
> Archive of previous messages: http://www.topica.com/lists/RE-wrenches/
>
> List rules & etiquette: http://www.mrsharkey.com/wrenches/etiquete.htm
>
> Check out participant bios: www.mrsharkey.com/wrenches/index.html
>
> Hosted by Home Power magazine
>
> Moderator: michael.welch at homepower.com
>
>
>
>
>
>



Brad Bassett
Schott Applied Power
Tumwater, WA office
bsbassett at earthlink.net

- - - -
To send a message: RE-wrenches at topica.com

Archive of previous messages: http://www.topica.com/lists/RE-wrenches/

List rules & etiquette: http://www.mrsharkey.com/wrenches/etiquete.htm

Check out participant bios: www.mrsharkey.com/wrenches/index.html

Hosted by Home Power magazine

Moderator: michael.welch at homepower.com

- - - -
To send a message: RE-wrenches at topica.com

Archive of previous messages: http://www.topica.com/lists/RE-wrenches/

List rules & etiquette: http://www.mrsharkey.com/wrenches/etiquete.htm

Check out participant bios: www.mrsharkey.com/wrenches/index.html

Hosted by Home Power magazine

Moderator: michael.welch at homepower.com

==^================================================================
This email was sent to: michael_welch at sbcglobal.net

EASY UNSUBSCRIBE click here: http://topica.com/u/?bz8Qcs.bz9JC9.bWljaGFl
Or send an email to: RE-wrenches-unsubscribe at topica.com

TOPICA - Start your own email discussion group. FREE!
http://www.topica.com/partner/tag02/create/index2.html
==^================================================================