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<DIV><div class=WordSection1><p class=MsoNormal><span style='font-size:11.0pt;font-family:"Calibri","sans-serif";color:#1F497D'>Allan:<o:p></o:p></span></p><p class=MsoNormal><span style='font-size:11.0pt;font-family:"Calibri","sans-serif";color:#1F497D'><o:p> </o:p></span></p><p class=MsoNormal><span style='font-size:11.0pt;font-family:"Calibri","sans-serif";color:#1F497D'>A pretty accurate retention of the Grass Valley / Nevada County through 2000.<o:p></o:p></span></p><p class=MsoNormal><span style='font-size:11.0pt;font-family:"Calibri","sans-serif";color:#1F497D'>You only missed the Trace to Xantrex “acquisition” that was the start of the divorce </span><span style='font-size:11.0pt;font-family:Wingdings;color:#1F497D'>J</span><span style='font-size:11.0pt;font-family:"Calibri","sans-serif";color:#1F497D'><o:p></o:p></span></p><p class=MsoNormal><span style='font-size:11.0pt;font-family:"Calibri","sans-serif";color:#1F497D'><o:p> </o:p></span></p><p class=MsoNormal><span style='font-size:11.0pt;font-family:"Calibri","sans-serif";color:#1F497D'>Class T fuses provide better protection for battery based inverters – always been that way.<o:p></o:p></span></p><p class=MsoNormal><span style='font-size:11.0pt;font-family:"Calibri","sans-serif";color:#1F497D'>The move to breakers was a cost reduction issues when Trace introduced the DC-250.<o:p></o:p></span></p><p class=MsoNormal><span style='font-size:11.0pt;font-family:"Calibri","sans-serif";color:#1F497D'>I still contend that the way the DC-250 did it was a Code violation when used with PV in the box (current from all sources issue) but that is history.<o:p></o:p></span></p><p class=MsoNormal><span style='font-size:11.0pt;font-family:"Calibri","sans-serif";color:#1F497D'><o:p> </o:p></span></p><p class=MsoNormal><span style='font-size:11.0pt;font-family:"Calibri","sans-serif";color:#1F497D'>For high current applications the Boltswitch Pull outs (the ones we used in the Power Centers) came in 100A, 200A and 400 A sizes and 1, 2, and 3 pole versions. <o:p></o:p></span></p><p class=MsoNormal><span style='font-size:11.0pt;font-family:"Calibri","sans-serif";color:#1F497D'>I think they are still made today.<o:p></o:p></span></p><p class=MsoNormal><span style='font-size:11.0pt;font-family:"Calibri","sans-serif";color:#1F497D'>Still the best way to do currents above 250 Amps.<o:p></o:p></span></p><p class=MsoNormal><span style='font-size:11.0pt;font-family:"Calibri","sans-serif";color:#1F497D'>You can do a Eaton / GJ1P breaker up to 750 Amps but they are Spin Dee.<o:p></o:p></span></p><p class=MsoNormal><span style='font-size:11.0pt;font-family:"Calibri","sans-serif";color:#1F497D'><o:p> </o:p></span></p><p class=MsoNormal><span style='font-size:11.0pt;font-family:"Calibri","sans-serif";color:#1F497D'>As you noted you can use a single pull out to do up to 3 battery strings.<o:p></o:p></span></p><p class=MsoNormal><span style='font-size:11.0pt;font-family:"Calibri","sans-serif";color:#1F497D'>You make a copper “comb” to parallel separate fused inputs to a single inverter. <o:p></o:p></span></p><p class=MsoNormal><span style='font-size:11.0pt;font-family:"Calibri","sans-serif";color:#1F497D'>If you have more than one inverter you can have “back to back” fuse blocks with an H-H-H shaped bus bar set up.<o:p></o:p></span></p><p class=MsoNormal><span style='font-size:11.0pt;font-family:"Calibri","sans-serif";color:#1F497D'>The biggest one I recall we did was a 12 400 A battery/PV inputs going to 8 SW inverters.<o:p></o:p></span></p><p class=MsoNormal><span style='font-size:11.0pt;font-family:"Calibri","sans-serif";color:#1F497D'>You size the copper bus bars for 1000 A / square inch of cross section and you are good to go (this is from the UL 508 design guide).<o:p></o:p></span></p><p class=MsoNormal><span style='font-size:11.0pt;font-family:"Calibri","sans-serif";color:#1F497D'><o:p> </o:p></span></p><div><p class=MsoNormal><span style='font-size:11.0pt;font-family:"Calibri","sans-serif";color:#1F497D'>Best Regards,<o:p></o:p></span></p><p class=MsoNormal><span style='font-size:11.0pt;font-family:"Calibri","sans-serif";color:#1F497D'><o:p> </o:p></span></p><p class=MsoNormal><span style='font-size:11.0pt;font-family:"Calibri","sans-serif";color:#1F497D'>John Berdner<o:p></o:p></span></p><p class=MsoNormal><span style='font-size:11.0pt;font-family:"Calibri","sans-serif";color:#1F497D'>General Manager, North America<o:p></o:p></span></p><p class=MsoNormal><span style='font-size:11.0pt;font-family:"Calibri","sans-serif";color:#1F497D'><o:p> </o:p></span></p><p class=MsoNormal><span style='font-size:11.0pt;font-family:"Calibri","sans-serif";color:#1F497D'>SolarEdge Technologies, Inc.<o:p></o:p></span></p><p class=MsoNormal><span style='font-size:11.0pt;font-family:"Calibri","sans-serif";color:#1F497D'>3347 Gateway Boulevard, Fremont CA 94538 USA </span><b><i><span style='font-size:11.0pt;font-family:"Calibri","sans-serif";color:#C00000'>(*Please note of our new address.)</span></i></b><span style='font-size:11.0pt;font-family:"Calibri","sans-serif";color:#1F497D'><br>T: 510.498.3200, X 747<o:p></o:p></span></p><p class=MsoNormal><span style='font-size:11.0pt;font-family:"Calibri","sans-serif";color:#1F497D'>M: 530.277.4894 <o:p></o:p></span></p></div><p class=MsoNormal><span style='font-size:11.0pt;font-family:"Calibri","sans-serif";color:#1F497D'><o:p> </o:p></span></p><div><div style='border:none;border-top:solid #B5C4DF 1.0pt;padding:3.0pt 0in 0in 0in'><p class=MsoNormal><b><span style='font-size:10.0pt;font-family:"Tahoma","sans-serif";color:windowtext'>From:</span></b><span style='font-size:10.0pt;font-family:"Tahoma","sans-serif";color:windowtext'> re-wrenches-bounces@lists.re-wrenches.org [mailto:re-wrenches-bounces@lists.re-wrenches.org] <b>On Behalf Of </b>Allan Sindelar<br><b>Sent:</b> Friday, April 05, 2013 9:00 PM<br><b>To:</b> RE-wrenches<br><b>Subject:</b> Re: [RE-wrenches] Fuse sizing in battery circuits<o:p></o:p></span></p></div></div><p class=MsoNormal><o:p> </o:p></p><div><p class=MsoNormal style='margin-bottom:12.0pt'>William,<br>For this I went deep into the catacombs of our hardware file cabinet, and quickly found a 1996 spec sheet from an Ananda Power Technologies SafeT-Block. For the young'uns, Ananda was a quality company, the originator of the listed Powercenter - the breaker and terminal block hardware that is part of every batttery-based system nowadays. Ananda became APT, then Pulse, then part of Trace (the PC250 and PC500) as part of a short-lived marriage followed by a messy divorce, the results of which led, as an act of revenge insurrection, to the introduction into the U.S. market of the Sunny Boy and AC-coupled systems, and the rest is even more wacky history. But I digress, after a run-on sentence bad enough that my high school English teacher is rolling over in her grave...<br><br>I have attached a scan of page two of the spec sheet. In the upper left corner is a chart of current vs. time for a Class T fuse. Once I understood this chart I never again worried about nuisance tripping, as whether described as fast-acting or not, Class T fuses have an inherent surge capacity of about 2 1/2 times their rating, and thus can handle surges.<br><br>If you put them on individual battery strings, the point is to prevent overcurrent on one string, which is only likely to occur when either 1) a terminal is corroded sufficiently that one string fails to carry its share of the load or charge (we have seen this) or 2) one string fails when the batteries reach end-of-life. When the Class T fuses blows in that situation it has done its job.<br>Allan<o:p></o:p></p><div><p class=MsoNormal><b>Allan Sindelar</b><br><span style='font-size:10.0pt'><a href="mailto:Allan@positiveenergysolar.com"><span style='color:#000099'>Allan@positiveenergysolar.com</span></a></span><br><span style='font-size:10.0pt'>NABCEP Certified Photovoltaic Installer<br>NABCEP Certified Technical Sales Professional<br>New Mexico EE98J Journeyman Electrician<br>Founder and Chief Technology Officer<br><b>Positive Energy, Inc.</b><br>3209 Richards Lane (note new address)<br>Santa Fe, New Mexico 87507<br><b>505 424-1112</b><br><a href="http://www.positiveenergysolar.com/" target="_blank">www.positiveenergysolar.com</a></span> <o:p></o:p></p><p class=MsoNormal style='mso-margin-top-alt:auto;margin-right:722.25pt;mso-margin-bottom-alt:auto'><br><img border=0 height=912 id="_x0000_i1025" src="cid:image001.png@01CE347B.2335C030" width=843><o:p></o:p></p><p class=MsoNormal><o:p> </o:p></p></div><p class=MsoNormal>On 4/5/2013 8:29 PM, William Miller wrote:<o:p></o:p></p></div><blockquote style='margin-top:5.0pt;margin-bottom:5.0pt'><p class=MsoNormal>Friends:<br><br>Good topic. Some questions:<br><br>1. Most manufacturer's present an installation guide that shows one OCPD in the battery circuit and that is in the BOS cabinet. This means the battery leads are unprotected. Do we need an OPCD at the battery terminals?<br><br>2. Class T fuses are generally recommended for this application. The data shows them as "fast acting." Is this a problem? Will they act too fast and open during normal surge loads?<br><br>Thanks in advance!<br><br>William Miller<br><br><br><br><br><br><br><o:p></o:p></p><p class=MsoNormal>Troy,<br> <br>Overcurrent device size is matched to the conductor size. The inverse time constant nature of an overcurrent device can typically handle the surge currents as long as conductor sizing has truly been done correctly for the conductor. Circuit breakers are preferred to fuses because they can be reset. <br> <br>There has been volumes written on this issue. The constant current at lowest battery voltage should be used, plus the ac ripple content on the battery circuit. This is usually a much larger conductor than your average designer will plan for. The best thing is to look at Midnight, Outback, and Schneider and see what size overcurrent devices they require for their products. That will give you a good clue as to how to size the conductor and overcurrent device.<br> <br>Bill.<br> <br><b>From:</b> <a href="mailto:re-wrenches-bounces@lists.re-wrenches.org">re-wrenches-bounces@lists.re-wrenches.org</a> [<a href="mailto:re-wrenches-bounces@lists.re-wrenches.org">mailto:re-wrenches-bounces@lists.re-wrenches.org</a>] <b>On Behalf Of </b>Troy Harvey<br><b>Sent:</b> Friday, April 05, 2013 3:38 PM<br><b>To:</b> RE-wrenches<br><b>Subject:</b> [RE-wrenches] Fuse sizing in battery circuits<br> <br>I've got a question about battery string fusing. Typically we size the wire from the batteries to the inverter based on continuous rating procedures (max power/efficiency)*125%. <br> <br>However a 6kW inverter, can peak at 12kW for 5-10 seconds, doubling the source current. That is no big deal for the wire, because it is a short time frame... little heat will be generated. However, in fusing the sub-strings, you need to account for that peak surge current so you don't blow fuses all the time. But if you put a 500-1000 amp fuse on a 4/0 wire, above the max surge draw of the inverter, the wire will be under-protected for its ampacity rating. Any thoughts on the catch-22?<br> <o:p></o:p></p><p class=MsoNormal><br><br><br><o:p></o:p></p><pre>_______________________________________________<o:p></o:p></pre><pre>List sponsored by Home Power magazine<o:p></o:p></pre><pre><o:p> </o:p></pre><pre>List Address: <a href="mailto:RE-wrenches@lists.re-wrenches.org">RE-wrenches@lists.re-wrenches.org</a><o:p></o:p></pre><pre><o:p> </o:p></pre><pre>Change email address & settings:<o:p></o:p></pre><pre><a href="http://lists.re-wrenches.org/options.cgi/re-wrenches-re-wrenches.org">http://lists.re-wrenches.org/options.cgi/re-wrenches-re-wrenches.org</a><o:p></o:p></pre><pre><o:p> </o:p></pre><pre>List-Archive: <a href="http://lists.re-wrenches.org/pipermail/re-wrenches-re-wrenches.org">http://lists.re-wrenches.org/pipermail/re-wrenches-re-wrenches.org</a><o:p></o:p></pre><pre><o:p> </o:p></pre><pre>List rules & etiquette:<o:p></o:p></pre><pre><a href="http://www.re-wrenches.org/etiquette.htm">www.re-wrenches.org/etiquette.htm</a><o:p></o:p></pre><pre><o:p> </o:p></pre><pre>Check out participant bios:<o:p></o:p></pre><pre><a href="http://www.members.re-wrenches.org">www.members.re-wrenches.org</a><o:p></o:p></pre><pre><o:p> </o:p></pre></blockquote><p class=MsoNormal><o:p> </o:p></p></div></DIV>
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