Re: RE Lab: Module Wiring [RE-wrenches] 2
Drake,
I made a mistake when I used table 690-7 voltage de-rate. That seems to just be for voltage correction factor, not amps. See 690-8 (a)(1) for the first 1.25 de-rate then 690-8 (b) for the second 1.25 de-rate, both for amps. Tell me how you read that and please tell me if I am looking at it wrong!
Do you have the 1999 Handbook? For those who aren't familiar with it, it's the one with blue boxes with all the extra explanations. It shows in figure 690-2 12 volts sub arrays with 5 modules paralleled. That is seems to be in contradiction with the codes wording.
Hope this helps,
Travis Creswell
----------
From: Drake Chamberlin - Electrical Energy <solar@eagle-access.net>
To: RE-wrenches@topica.com
Subject: RE Lab: Module Wiring [RE-wrenches]
Date: Thu, Apr 27, 2000, 6:07 PM
Hi Wrenches,
I went through the Siemens Web site to get answers to the question of daisy chaining series strings of modules. It appears that there is no fuse required between the Series sets anymore.
Below is the response from Arthur Rudin of Siemens concerning my question.
*********************************************************************************************
Hi Drake,
Sorry for the delay in this response. I have been travelling and did not
have access to my e-mail. The NEC does require a fuse for each source
circuit. Modules or strings can be wired in parallel as long as the total
short circuit current x 1.25 does not exceed the series fuse rating of the
module. This is explained in article 690 of the NEC and the NEC handbook.
You can check your library for this information.
Best regards,
Arthur
*****************************************************************************************
Siemens apparently has no other requirement for their module wiring than the NEC specifications.
So if Siemens is going to let us meet the Code requirements for module wiring, without using extra fuses between the series pairs, we are safe daisy chaining strings of Siemens modules, and then going to one overcurrent device.
We can omit those pesky fuses between series strings of modules. There is no need for multiple whips to combiner boxes, with all the terminal strips, etc. This is the new Code, and it is a lot easier than the last.
Drake
RE Lab
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To: RE-wrenches@topica.com
From: Bob-O Schultze
Subject: Re: SW-4048/T240/230V 2-wire 175' well pump [RE-wrenches]
Date: Fri, 28 Apr 2000 08:28:56 -0700
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Ken,
Hard to guess without an eyeball, but your RE system should run that
pump with one hand tied behind it's back. Given that the problem
happens when you're grid connected and in float mode, it pretty much
eliminates the RE system entirely, except that everything goes thru
the T-240 which will start to flat top at some point if there is
enough current flowing through it to OTHER uses at the same time.
Assuming that isn't the case and your wiring to the P. tank and pump
is OK, it probably puts it down to the P. tank or the P. switch. As
you know, most (but not all) P.switches will not automatically
connect if the pressure drops below 10psi. You have to manually
override with the little lever. I'd try replacing the P.switch just
because it's cheaper!
Good Luck, bob-O
>The system is an SW4048/8-LC-16HC batteries/T-240 stepup xmfr/240 VAC, 1/2
>hp well pump at 175 ft. Well perodically shuts down with zero pressure at
>the pressure switch.
>
>The problem is the well keeps shutting down (0 pressure at the pressure
>switch)--2-3 times per week. Upon checking the buried pressure tank,
>pressure in the bladder was zero. Brought pressure up to 30# (with system
>drained), and all worked fine. The next day, pressure was back to zero, but
>bladder retained 30# of pressure (so I believe that bladder is not breached,
>although I didn't dig it up again. One interesting departure: Before, the
>water trickled out of the tap until there was nothing left. The last time,
>it stopped abruptly, as though, instantly, there was no water. This makes
>sense if you consider that there was no water left in the pressure tank and
>the bladder was full of air)
>
>The capacitor fix rang a bell, however this is a different situation.
>Although connected, the system is not running off the inverter--it's running
>off Mains, without power interruption. Even if Mains power was interrupted,
>the inverter/batteries should instantly take over.
>
>The system runs through the T240 in all cases, to drive the well pump, and
>the SW4048 is always in the float mode, with AC Mains applied. The solar
>panels are not up yet, so the system is complete and running off Mains.
>
>I cleaned pressure switch contacts. The last two, prior water cut-offs were
>after a big rain, so I don't think it's a matter of the well running dry.
>Each time I restart the pressure switch, the pressure tank fills up with
>plenty of water (14 gallon draw-down, buried pressure tank, located at the
>well).
>
>Does anyone have any ideas of what the problem is?
>
>Ken
>AB4JB
>
>
>Ken C. Falk, CCIM*
>E-mail: falk@investusa.net
>Back-up E-mail: kenfalk@hotmail.com
>Kenneth C. Falk Real Estate Broker, Inc.
>Commercial, Investment & Industrial Real Estate
>1282 Poplar Hill Road
>Lexington, Virginia 24450-7332 USA
>(540) 464-3405 Fax: (540) 464-4200
>Web site: http://www.investusa.net/
>(*Certified Commercial Investment Member)
>
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>
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>
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>
>
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>
>for info contact:
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Bob-O Schultze, Electron Connection
PO Box 203, Hornbrook, CA 96044
800.945.7587 fax 530-475-3401
www.electronconnection.com
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