The normal UL DC rating on the Square D QOU breakers is 50VDC but that is with a fairly high interrupt current (i.e. for battery/load circuits). As part of the UL listing process for the APT power center the breakers were evaluated for use up to 100 VDC with low interrupt current levels - i.e. PV arrays. The switchover to the Heinemann breakers was done for other reasons and they also allow higher open circuit voltages - up to 165VDC.
So - I would not be concerned about using the existing Square D QOU breakers as long as the open circuit voltage of the PV array doesn't exceed the 100 VDC level. Christopher Christopher Freitas Director of Research and Development OutBack Power Systems, Inc. [email protected] <mailto:[email protected]> Tel 360 435 6030 Cell 360 202 4239 19009 62nd Ave NE Arlington WA 98223 USA www.outbackpower.com <http://www.outbackpower.com/> ________________________________ From: [email protected] [mailto:[email protected]] On Behalf Of Allan Sindelar Sent: Thursday, January 01, 2009 7:16 AM To: 'RE-wrenches' Subject: Re: [RE-wrenches] Pulse 250 power center Bob and Joel, Depends on the powercenter model. Only the oldest APT/Ananda models used Square D QOU breakers for DC. APT's later units (the 4B) used QOU only for AC, and used Heinemann CF for DC. By the time the brand was Pulse all DC breakers were Heinemann (or maybe equivalent Airpax), and thus rated 125V DC. The bigger problem was that the later models (and other models too) lacked sufficient breaker spaces; the 4B had 5. With 2 for PV input, 2 for PVGFP, and 1 for DC loads, that left no room for expansion. By the way, what is the name of the most recent iteration of Pulse, that followed Connect Energy? Just a few years ago, they were developing a 48V grid-tied with batteries inverter. I had also heard that they had none of the earlier personnel, just the name and intellectual property, and were to be approached very cautiously. Allan -----Original Message----- From: [email protected] [mailto:[email protected]] On Behalf Of robert ellison The better bet is the MPPT controller but keep in mind that the original breakers are not rated for the series panel strings that we use now. The Square D breakers are only UL rated for 50 volts not the typical 70 - 96 volts we see now. Here's to a great new year, Bob On Wed, Dec 31, 2008 at 1:26 PM, Joel Davidson <[email protected]> wrote: Hi Allan, Good idea bypassing the old charge controller. I'll pass it on to our customer. ...and good memory. The Ananda people did the PV industry a real service by making the first UL listed power center. MESSAGE CONFIDENTIALITY NOTICE: This message (including attachments) is covered by the Electronic Communication Privacy Act, 18 U.S.C. sections 2510-2521, is confidential, and may also be protected by attorney-client or other privilege. If you believe that it has been sent to you in error, please do not read it. If you are not the intended recipient,you are hereby notified that any retention, dissemination, distribution, or copying of this communication is strictly prohibited. Please reply to the sender that you have received the message in error, then delete it. Thank you.
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