Re: [RE-wrenches] var/ power factor
Ok, I'll bite.First, some diffnitions.. from Delmer's Standard (ISBN-13: 978-1-4180-6580-5):Apparent Power (VA) is the value found by multiplying the applied voltage by the total current of an AC circuit. Apparent power is measured in volt-amps (VA) and should not be confused with true power, measured in watts."Power Factor (PF) is a comparison of the true power (Resistive, or Watts) to the Apparent power (Volt Amps) in an AC circuit.""Reactive power (VARs or Volt Amps Reactive... sometimes called "wattless power"), is calculated by multiplying reactive voltage by reactive current. Which can be produced by inductive or capacitive loads.". (The key concept here is the notion that there is funny reactive stuff going on opposing input stuff).. there's also a few different resistances to get your head around (I've tried to attach a cheat Sheet from E2.. but I guess the file was too big, so it got kicked back... contact me off list and I can send it along)..anyway, Assuming you're in single phase parallel land (AC).. : First, there's a pure resistance measured in ohms (Greek letter omega), opposing current flow across any purely resistive loads.. (power in this part of the circuit is measured in watts.. current is in phase with voltage)... there's also a current limiting property opposing current flow across any inductive loads.. it's also measured in ohms, but is called XL.. or Inductive Reactance... funny thing about this stuff is that it's not really a resistance.. it's more of a reaction to magnetic fields.. so the current wave form lags the voltage wave form by 90 degrees... Power in this part of the circuit is tabbed VARsL... similarly there's a resistance opposing current flow (or something like it) in capacitive loads.. also measured in ohms. this resistance is given the handle of Xc... or Capacitive Reactance. Power in this part of the circuit is tabbed VARsc .. this current leads the voltage wave form by 90 degrees, and is 180 degrees out of phase with any inductive current .. so you can subtract the smaller from the larger, and come up with a total VARs for the circuit.. which might be either inductive or capacitive.. and because the relationship of either wave form is 90 degrees out of phase from resistive power, we can use right angle trig. to keep tabs. Chuck Thompson (E1) taught us the phrase "ELI the ICE man" to help us keep things straight. Finally, there's Z (or total circuit impedance or "total opposition to current flow in an AC circuit"), and is calculated from ohms, XL and Xc. Z can be substituted for R total circuit calculations... I think..--So-- The way I like to make sense of it.. when you stuff AC power into a purely resistive circuit, it consumes watts. the current wave form is in phase with the voltage wave form so the resistive force pushes straight back on applied power... (twinkle, twinkle little star, power = I squared R). When you stuff AC power into a combination AC circuit (resistive, inductive, and maybe capacitive.. like a motor), really funny things happen.. you can still walk up and measure stuff with your meter (and you still see Volts and Amps ), but you're seeing "apparent power".. (VA).. the current wave form is likely not in phase with the voltage wave form, so rather than there being a resistance opposing current flow directly, there's now a "funny power" pushing back the on the applied power.. a reactive power (VARs). which can be either inductive (lagging), or capacitive (leading). that means VARs is oppositional to VA... And Power Factor (PF) is the ratio of Watts/ Volt Amps (VA).So, the way I see it, VA is total apparent power.. stuff you can see... VARs is reactive power.. (funny power pushing back on applied power)... So that means that if there is no VARs, (XL=Xc), there is no out of phase (funny power) opposing input power... which would make the Power Factor (PF= W/VA)=1. Now I have been known to be full of... beans, so if I've oopsied some, please chime in.. thanks. hope this helps. dbComments?Dan BrownFoxfire Energy Corp.Renewable Energy Systems(802)-483-2564www.Foxfire-Energy.comNABCEP #092907-44Dan BrownPresidentFoxfire Energy Corp.Renewable Energy Systems(802)-483-2564www.Foxfire-Energy.comNABCEP #092907-44 Original Message Subject: Re: [RE-wrenches] var/ power factor From: Kent Osterberg k...@coveoregon.com Date: Fri, May 14, 2010 1:35 pm To: RE-wrenches re-wrenches@lists.re-wrenches.org Todd, You are getting credit for all the energy your system can produce. Turn off the humidify and you'll see the power factor go up to nearly 1.0. That's what the inverter is operating at, regardless of whether the humidifier is on or off. Say the PF is 80% without the inverter running. That means the utility is providing some reactive power or VARs. With the inverter running, the real power delivered by the utility is reduced, but the reactive power is not
Re: [RE-wrenches] AC breakers used in DC applications
Square-D tells me they have tested the breakers to a higher voltage (can't recall now whether it was 80V or 125 VDC) but the listing is indeed for 48 Volts. 24V battery systems are useful for a lot of applications, but the unfortunate lack of a 5A breaker means we can not use them to derive a Class 2 supply, which would make them about 10x as useful to me. On May 15, 2010, at 9:22 , jay peltz wrote: Hi Rebekah, The 48v is a max rating not a nominal rating. So yes only good for 12 and 24v systems. However with CBI breakers I don't understand why the need for QO for DC anymore? jay peltz power On May 15, 2010, at 6:28 AM, Rebekah Hren wrote: Hi, One thing to be clear about is whether these are listed for 48 volt systems, or for max 48 volts? I was under the impression that they were max 48 volts, meaning you really shouldn't use them on a system 24volts nominal. Rebekah Hren North Carolina http://thecarbonfreehome.com/ --- On Sat, 5/15/10, Kurt Albershardt i...@es-ee.com wrote: From: Kurt Albershardt i...@es-ee.com Subject: Re: [RE-wrenches] AC breakers used in DC applications To: RE-wrenches re-wrenches@lists.re-wrenches.org Date: Saturday, May 15, 2010, 12:59 AM The Square-D catalogs are marginally clear on which breakers are listed for DC and for what voltages, but when I tried to select an appropriate load center for a DC application earlier this year I quickly ran into a number of conflicts in their catalogs. Here is the response from Schneider tech support (Case# 4845778 on 1/19/10 in case anyone runs into problems with an inspector): The load center catalog numbers listed below are UL LISTED, File E6294, for use on 48 V dc systems. The load centers listed ARE NOT MARKED for use on this voltage system, however are suitable for the application. QO branch breakers, 10-70 ampere (1 and 2 pole) are also UL LISTED for use on 48V dc systems. Short circuit current rating is limited to 5,000 amperes when used on 48V dc. QO24L70F, S or RB QO612L100F, S, DF, DS, DFCU, DSCU, RB, TRB or RBCU QO816L100F, S, DF, DS, DFCU, DSCU, RB or RBCU QO112L125G or QO11224L125G QO116L125G QO11624L125G QO120L125G QO12024L125G QO124L125G or QO12030L150G QO124L150G QO130L150G or QO112L200G or QO130L200G or QO13040L200G QO142L225G or GRB or GRB or GRB GRB GRB GRB GRB or GRB QO142L225GRB I can email the PDF to anyone who needs a copy. ___ List sponsored by Home Power magazine List Address: RE-wrenches@lists.re-wrenches.org Options settings: http://lists.re-wrenches.org/options.cgi/re-wrenches-re-wrenches.org List-Archive: http://lists.re-wrenches.org/pipermail/re-wrenches-re-wrenches.org List rules etiquette: www.re-wrenches.org/etiquette.htm Check out participant bios: www.members.re-wrenches.org ___ List sponsored by Home Power magazine List Address: RE-wrenches@lists.re-wrenches.org Options settings: http://lists.re-wrenches.org/options.cgi/re-wrenches-re-wrenches.org List-Archive: http://lists.re-wrenches.org/pipermail/re-wrenches-re-wrenches.org List rules etiquette: www.re-wrenches.org/etiquette.htm Check out participant bios: www.members.re-wrenches.org
Re: [RE-wrenches] AC breakers used in DC applications
Voltage is not the issue here, it is current, and battery fault currents can be staggering - far more than one would ever encounter in a typical AC system fed from a distribution transformer. I have seen a 200A Class T fail to act on an 48V inverter fault which resulted in welding the metal tabs of the fuse holder (which had been greased with copper-laden Penetrox E) to their sockets. That indicates a fault current well north of 200,000 amps, quite possibly sseveral times that. A fire ensued, which triggered the gas protection system and fortunately resulted in almost no peripheral damage. It did cost about $10k to recharge and recertify the Inergen system. The inverter manufacturer was quite cagey on warranty replacement until they saw the photos - at which point a replacement miraculously arrived by overnight air. On May 15, 2010, at 9:43 , Drake Chamberlin wrote: I did see a QO breaker fail to trip on a 24 volt DC system with only battery voltage behind it. It burned a #12 wire completely in two. The 48v is a max rating not a nominal rating. So yes only good for 12 and 24v systems. However with CBI breakers I don't understand why the need for QO for DC anymore? jay peltz power On May 15, 2010, at 6:28 AM, Rebekah Hren wrote: Drake Chamberlin Athens Electric OH License 44810 CO License 3773 NABCEP TM Certified PV Installer Office - 740-448-7328 Mobile - 740-856-9648 ___ List sponsored by Home Power magazine List Address: RE-wrenches@lists.re-wrenches.org Options settings: http://lists.re-wrenches.org/options.cgi/re-wrenches-re-wrenches.org List-Archive: http://lists.re-wrenches.org/pipermail/re-wrenches-re-wrenches.org List rules etiquette: www.re-wrenches.org/etiquette.htm Check out participant bios: www.members.re-wrenches.org
Re: [RE-wrenches] AC breakers used in DC applications
Small (QO or Airpax-type) breakers in a distribution bank should be front ended with a suitable DC master breaker or fuse that has the capability to interrupt the available fault current. Ideally, the series combination should be rated but at a minimum, a coordination study should be undertaken. I like to have primary protection on each string, as close to the battery as possible - preferably bolted to the battery terminal. Cable limiters are nice, but a TPL style fuse is easier to get. On May 16, 2010, at 16:13 , Kurt Albershardt wrote: Voltage is not the issue here, it is current, and battery fault currents can be staggering - far more than one would ever encounter in a typical AC system fed from a distribution transformer. I have seen a 200A Class T fail to act on an 48V inverter fault which resulted in welding the metal tabs of the fuse holder (which had been greased with copper-laden Penetrox E) to their sockets. That indicates a fault current well north of 200,000 amps, quite possibly several times that. A fire ensued, which triggered the gas protection system and fortunately resulted in almost no peripheral damage. It did cost about $10k to recharge and recertify the Inergen system. The inverter manufacturer was quite cagey on warranty replacement until they saw the photos - at which point a replacement miraculously arrived by overnight air. On May 15, 2010, at 9:43 , Drake Chamberlin wrote: I did see a QO breaker fail to trip on a 24 volt DC system with only battery voltage behind it. It burned a #12 wire completely in two. The 48v is a max rating not a nominal rating. So yes only good for 12 and 24v systems. However with CBI breakers I don't understand why the need for QO for DC anymore? jay peltz power On May 15, 2010, at 6:28 AM, Rebekah Hren wrote: Drake Chamberlin Athens Electric OH License 44810 CO License 3773 NABCEP TM Certified PV Installer Office - 740-448-7328 Mobile - 740-856-9648 ___ List sponsored by Home Power magazine List Address: RE-wrenches@lists.re-wrenches.org Options settings: http://lists.re-wrenches.org/options.cgi/re-wrenches-re-wrenches.org List-Archive: http://lists.re-wrenches.org/pipermail/re-wrenches-re-wrenches.org List rules etiquette: www.re-wrenches.org/etiquette.htm Check out participant bios: www.members.re-wrenches.org
Re: [RE-wrenches] AC breakers used in DC applications
My understanding was that the din mountable QOU breakers were rated to 125 vDC, and are internally the same as the QO. The difference was the connectors, and the mounting method. I've used the QOUs reliably at 120 v nom on an EV, (but don't try this at home, kids) We still use the QOs sometimes based on cost and availability, but I don't use them on anything over 24 v nominal anymore. They were handiest in that one breaker line could cover AC and low volt DC. With MPPT high voltage arrays, and some of Midnite Solar's new products (Mini DC Baby DC boxes), though, we've found less and less of a place for the venerable QO line. R. Walters r...@solarray.com Solar Engineer On May 16, 2010, at 2:25 PM, Kurt Albershardt wrote: Square-D tells me they have tested the breakers to a higher voltage (can't recall now whether it was 80V or 125 VDC) but the listing is indeed for 48 Volts. 24V battery systems are useful for a lot of applications, but the unfortunate lack of a 5A breaker means we can not use them to derive a Class 2 supply, which would make them about 10x as useful to me. On May 15, 2010, at 9:22 , jay peltz wrote: Hi Rebekah, The 48v is a max rating not a nominal rating. So yes only good for 12 and 24v systems. However with CBI breakers I don't understand why the need for QO for DC anymore? jay peltz power On May 15, 2010, at 6:28 AM, Rebekah Hren wrote: Hi, One thing to be clear about is whether these are listed for 48 volt systems, or for max 48 volts? I was under the impression that they were max 48 volts, meaning you really shouldn't use them on a system 24volts nominal. Rebekah Hren North Carolina http://thecarbonfreehome.com/ --- On Sat, 5/15/10, Kurt Albershardt i...@es-ee.com wrote: From: Kurt Albershardt i...@es-ee.com Subject: Re: [RE-wrenches] AC breakers used in DC applications To: RE-wrenches re-wrenches@lists.re-wrenches.org Date: Saturday, May 15, 2010, 12:59 AM The Square-D catalogs are marginally clear on which breakers are listed for DC and for what voltages, but when I tried to select an appropriate load center for a DC application earlier this year I quickly ran into a number of conflicts in their catalogs. Here is the response from Schneider tech support (Case# 4845778 on 1/19/10 in case anyone runs into problems with an inspector): The load center catalog numbers listed below are UL LISTED, File E6294, for use on 48 V dc systems. The load centers listed ARE NOT MARKED for use on this voltage system, however are suitable for the application. QO branch breakers, 10-70 ampere (1 and 2 pole) are also UL LISTED for use on 48V dc systems. Short circuit current rating is limited to 5,000 amperes when used on 48V dc. QO24L70F, S or RB QO612L100F, S, DF, DS, DFCU, DSCU, RB, TRB or RBCU QO816L100F, S, DF, DS, DFCU, DSCU, RB or RBCU QO112L125G or QO11224L125G QO116L125G QO11624L125G QO120L125G QO12024L125G QO124L125G or QO12030L150G QO124L150G QO130L150G or QO112L200G or QO130L200G or QO13040L200G QO142L225G or GRB or GRB or GRB GRB GRB GRB GRB or GRB QO142L225GRB I can email the PDF to anyone who needs a copy. ___ List sponsored by Home Power magazine List Address: RE-wrenches@lists.re-wrenches.org Options settings: http://lists.re-wrenches.org/options.cgi/re-wrenches-re-wrenches.org List-Archive: http://lists.re-wrenches.org/pipermail/re-wrenches-re-wrenches.org List rules etiquette: www.re-wrenches.org/etiquette.htm Check out participant bios: www.members.re-wrenches.org ___ List sponsored by Home Power magazine List Address: RE-wrenches@lists.re-wrenches.org Options settings: http://lists.re-wrenches.org/options.cgi/re-wrenches-re-wrenches.org List-Archive: http://lists.re-wrenches.org/pipermail/re-wrenches-re-wrenches.org List rules etiquette: www.re-wrenches.org/etiquette.htm Check out participant bios: www.members.re-wrenches.org ___ List sponsored by Home Power magazine List Address: RE-wrenches@lists.re-wrenches.org Options settings: http://lists.re-wrenches.org/options.cgi/re-wrenches-re-wrenches.org List-Archive: http://lists.re-wrenches.org/pipermail/re-wrenches-re-wrenches.org List rules etiquette: www.re-wrenches.org/etiquette.htm Check out participant bios: www.members.re-wrenches.org
[RE-wrenches] Solmetric Suneye 210
Has anyone had any experience with the fairly new Solmetric Suneye 210 shading analysis tool? Feedback and observations? Or how about with their earlier version the Suneye 110? Thanks, marco provision_highres_solar_logo2 with C-26351 Marco Mangelsdorf, President 69 Railroad Avenue, A-7 Hilo, Hawai'i 96720 (808) 969-3281, 934-7462 facsimile http://www.provisiontechnologies.com www.provision-solar.com image001.jpg___ List sponsored by Home Power magazine List Address: RE-wrenches@lists.re-wrenches.org Options settings: http://lists.re-wrenches.org/options.cgi/re-wrenches-re-wrenches.org List-Archive: http://lists.re-wrenches.org/pipermail/re-wrenches-re-wrenches.org List rules etiquette: www.re-wrenches.org/etiquette.htm Check out participant bios: www.members.re-wrenches.org
Re: [RE-wrenches] AC breakers used in DC applications
Kurt Fascinating story and valuable information. This is the kind of real world experience we need to draw on. Reality can change quickly under extreme conditions and one's education is not complete without this understanding. Thanks for this post. William Miller PS: You are fortunate your client had a proper fire suppression system. I doubt many of us can count on that to minimize damage. Wm At 03:13 PM 5/16/2010, you wrote: Voltage is not the issue here, it is current, and battery fault currents can be staggering - far more than one would ever encounter in a typical AC system fed from a distribution transformer. I have seen a 200A Class T fail to act on an 48V inverter fault which resulted in welding the metal tabs of the fuse holder (which had been greased with copper-laden Penetrox E) to their sockets. That indicates a fault current well north of 200,000 amps, quite possibly sseveral times that. A fire ensued, which triggered the gas protection system and fortunately resulted in almost no peripheral damage. It did cost about $10k to recharge and recertify the Inergen system. The inverter manufacturer was quite cagey on warranty replacement until they saw the photos - at which point a replacement miraculously arrived by overnight air. ___ List sponsored by Home Power magazine List Address: RE-wrenches@lists.re-wrenches.org Options settings: http://lists.re-wrenches.org/options.cgi/re-wrenches-re-wrenches.org List-Archive: http://lists.re-wrenches.org/pipermail/re-wrenches-re-wrenches.org List rules etiquette: www.re-wrenches.org/etiquette.htm Check out participant bios: www.members.re-wrenches.org
