NAWS battery disconnect switch 9001e rating questions 48 volts maybe ?

new2PVnew2PV Solar Expert Posts: 305 ✭✭
HI, NAWS has these switches, but they are rated at 32 volts, but It says on the front and back 48 volts? I want to use the 3 position switch on my 48 volt battery bank which will be charged at 57 volts...Is this an issue?

http://www.solar-electric.com/basw1300amp.html
XW6848 inverter with 2 X mppt 60 150 CC , with Canadian solar 260Watt panels 2 x 3.5 kw array

Comments

  • inetdoginetdog Solar Expert Posts: 3,123 ✭✭✭✭
    new2PV wrote: »
    HI, NAWS has these switches, but they are rated at 32 volts, but It says on the front and back 48 volts? I want to use the 3 position switch on my 48 volt battery bank which will be charged at 57 volts...Is this an issue?

    http://www.solar-electric.com/basw1300amp.html
    Is this an issue? Yes!

    The 32V figure is the nominal system voltage that NAWS recommends. That leaves room for cold temperatures and occasional equalization charging and still staying under 48V.
    A nominal 48v system can easily approach 60 volts. That is too far beyond the UL rating of the switch, even allowing that the rating is conservative. I would not stake my safety on it.

    The rating is based in part on the insulation withstand voltage of the components, but also on the ability to open under load and quench the resulting DC arc. The voltage difference may not exceed the insulation rating, but it will affect the arc quenching seriously.
    SMA SB 3000, old BP panels.
  • new2PVnew2PV Solar Expert Posts: 305 ✭✭
    OK, they also have the 2 position switch and its rated at 48 volts DC, this not going to be safe either? Thanks for you help.
    XW6848 inverter with 2 X mppt 60 150 CC , with Canadian solar 260Watt panels 2 x 3.5 kw array
  • inetdoginetdog Solar Expert Posts: 3,123 ✭✭✭✭
    new2PV wrote: »
    OK, they also have the 2 position switch and its rated at 48 volts DC, this not going to be safe either? Thanks for you help.

    I cannot answer that without more information. If the listing implies that it can be used with a 48V nominal system rather than having an absolute max voltage of 48V, you might be OK. You can always call NAWS and ask!
    SMA SB 3000, old BP panels.
  • new2PVnew2PV Solar Expert Posts: 305 ✭✭
    I have sent them an email, as I hope I can use it, since I am not sure what other switch would work for the DC side to carry so many amps..
    XW6848 inverter with 2 X mppt 60 150 CC , with Canadian solar 260Watt panels 2 x 3.5 kw array
  • inetdoginetdog Solar Expert Posts: 3,123 ✭✭✭✭
    new2PV wrote: »
    I have sent them an email, as I hope I can use it, since I am not sure what other switch would work for the DC side to carry so many amps..
    It is hard to find such switches. Now if you were able to guarantee that it would never be opened under load, you might have more room to push the limits.

    PS: for switches designed to go from one battery bank to another, be very wary of the position that shorts the two banks together. In RE applications the current flowing between two banks at different SOC can be frightening.

    SMA SB 3000, old BP panels.
  • new2PVnew2PV Solar Expert Posts: 305 ✭✭
    I only want the switch in the event of an emergency or maintenance, I won;t be turning it on an off much..I did find a similar switch made in Taiwan..rated for 48v but it makes me nervous..
    XW6848 inverter with 2 X mppt 60 150 CC , with Canadian solar 260Watt panels 2 x 3.5 kw array
  • vtmapsvtmaps Solar Expert Posts: 3,738 ✭✭✭✭
    new2PV wrote: »
    HI, NAWS has these switches, but they are rated at 32 volts, but It says on the front and back 48 volts? I want to use the 3 position switch on my 48 volt battery bank which will be charged at 57 volts...Is this an issue?

    http://www.solar-electric.com/basw1300amp.html

    read this: http://www.amplepower.com/primer/burnt_sw/index.html

    --vtMaps
    4 X 235watt Samsung, Midnite ePanel, Outback VFX3524 FM60 & mate, 4 Interstate L16, trimetric, Honda eu2000i
  • inetdoginetdog Solar Expert Posts: 3,123 ✭✭✭✭
    vtmaps wrote: »
    A nice expose.
    If I recall correctly the unit that failed was a cheap off-shore imitation product and not one of the well respected Blue Sea products. But it does show in general what can go wrong at high currents with a poor design.
    SMA SB 3000, old BP panels.
  • new2PVnew2PV Solar Expert Posts: 305 ✭✭
    We will see what NAWS has to say about the blue sea stuff, I should know monday...
    XW6848 inverter with 2 X mppt 60 150 CC , with Canadian solar 260Watt panels 2 x 3.5 kw array
  • VicVic Solar Expert Posts: 3,082 ✭✭✭✭
    Hi new2..,

    As inetdog has mentioned, these switches are NOT rated for a 48 V battery system.

    AND, IMO, these switches would most probably not be Code in residential, or commercial power systems.

    Believe that your system is still a Grid-connected Backup Power system, or similar, so being Code and possibly needing to pass Inspections would probably be important to you.

    Real DC-Rated circuit breaker/s should be able to accomplish much of what you are trying to do, could easily be mounted in a metal box, and pass Inspections -- to the extent that inspections would be necessary.

    But Inspections or not, believe that a DC switch-rated breaker mounted in a metal enclosure would be the safest thing to do, without spending a lot of money on some other approach.

    More opinions. Good Luck, Vic

    Off Grid - Two systems -- 4 SW+ 5548 Inverters, Surrette 4KS25 1280 AH [email protected], 11.1 KW STC PV, 4X MidNite Classic 150 w/ WBjrs, Beta KID on S-530s, MX-60s, MN Bkrs/Boxes.  25 KVA Polyphase Kubota diesel,  Honda Eu6500isa,  Eu3000is-es, Eu2000,  Eu1000 gensets.  Thanks Wind-Sun for this great Forum.
  • new2PVnew2PV Solar Expert Posts: 305 ✭✭
    Well, I will have the 250A breaker still inside the WX PDP, but the batteries are located outside. I will check the code if the disconnect has to be within site of the batteries, then I will need a metal enclosure and extra breaker. The 2 position sw has a 48 vdc rating we are not sure it its nominal or max...
    XW6848 inverter with 2 X mppt 60 150 CC , with Canadian solar 260Watt panels 2 x 3.5 kw array
  • VicVic Solar Expert Posts: 3,082 ✭✭✭✭
    Hi again new2,

    It is the sense of many here, that you are trying to do things correctly, at least, this is my opinion.

    SO, in spite of what you appear to want others to say, I M O, These battery switches are NOT APPROPRIATE for application in systems with 48 V batteries, or any system with a battery voltage above 32 V nominal, as I read Wind-Sun's advice.

    Additionally, even if these switches were actually rated for 48 V Flooded battery applications, my guess is that they would not be Code ... just an additional opinion.

    You will probably want some form of protection -- a circuit breaker of fuse -- for each string of batteries. When you select an appropriate DC rated breaker, and mount them correctly in a Listed enclosure, you should be able to have most of or all of the function that you wish the B S switch to perform, save for low cost.

    EDIT: It is a bit curious that the "Sales Sheet" that is Linked to from the wind-sun site, shows an image of a switch that says "32 V Max", and some of the switches shown on the W-S site DO say 48 V Max. But, still, to me Max means Maximum -- never to exceed, etc < end edit.

    I am not a Code guru, so quite possibly, I'm wrong about the Code aspects.

    All FWIW, Vic
    Off Grid - Two systems -- 4 SW+ 5548 Inverters, Surrette 4KS25 1280 AH [email protected], 11.1 KW STC PV, 4X MidNite Classic 150 w/ WBjrs, Beta KID on S-530s, MX-60s, MN Bkrs/Boxes.  25 KVA Polyphase Kubota diesel,  Honda Eu6500isa,  Eu3000is-es, Eu2000,  Eu1000 gensets.  Thanks Wind-Sun for this great Forum.
  • new2PVnew2PV Solar Expert Posts: 305 ✭✭
    I think I will just go with anderson connectors rated at 350Amps. My main breaker is 250 amps, and according to code I don;t need to fuse the strings, as long as each string has the ampacity to support the main breaker ahead of it, which 4/0 will support. In case I need to do some maintenance I can shut off the main breaker and pull apart the Anderson connectors. However I will have to buy a crimp tool for them.
    XW6848 inverter with 2 X mppt 60 150 CC , with Canadian solar 260Watt panels 2 x 3.5 kw array
  • VicVic Solar Expert Posts: 3,082 ✭✭✭✭
    Hi new2,

    Well, the protective Fuse or Breaker that I was trying to refer to is the device that protects each parallel string from Fault currents resulting from a short in a battery. These fault currents can be quite high.

    Recall that the fusing current for 4/0 copper cable is a bit over 3,000 amps. So it is fairly common Safety practice to place an OCPD in each parallel battery string to keep huge fault currents from causing a battery explosion, etc.

    Again, we each have our own style in designing a power system, so if Power Pole connectors go with your motif, then, go for it ... you have a fairly large investment in your system, especially after you get the PV modules and racking, etc ... but ...

    Good Luck, Vic
    Off Grid - Two systems -- 4 SW+ 5548 Inverters, Surrette 4KS25 1280 AH [email protected], 11.1 KW STC PV, 4X MidNite Classic 150 w/ WBjrs, Beta KID on S-530s, MX-60s, MN Bkrs/Boxes.  25 KVA Polyphase Kubota diesel,  Honda Eu6500isa,  Eu3000is-es, Eu2000,  Eu1000 gensets.  Thanks Wind-Sun for this great Forum.
  • new2PVnew2PV Solar Expert Posts: 305 ✭✭
    Well, if you put it that way, maybe that would be a good idea, I was just looking at the code rules for DC systems, and it just states one breaker is required, but based on your comments, maybe I should look into a disonnecting combiner box that can support 2 dc breakers 120 amps each and mount it close to my batteries. I want this to be a safe system, but I dont see anything that would work on the site. I could just add another 250a breaker to the PDP. Now I have doubled my cable length even more. How about 1 fuse in one parallel string connection? Schneider makes a 250A fused combiner box, maybe this is the best solution, as it has a bus bar to combine 3 banks rated at the full 250 Amps.
    XW6848 inverter with 2 X mppt 60 150 CC , with Canadian solar 260Watt panels 2 x 3.5 kw array
  • inetdoginetdog Solar Expert Posts: 3,123 ✭✭✭✭
    Vic wrote: »

    EDIT: It is a bit curious that the "Sales Sheet" that is Linked to from the wind-sun site, shows an image of a switch that says "32 V Max", and some of the switches shown on the W-S site DO say 48 V Max. But, still, to me Max means Maximum -- never to exceed, etc < end edit.


    All FWIW, Vic
    One possibility is that the manufacturer decided to avoid confusion and possible liability and mark the switch with the nominal system voltage of 32V, allowing for an Equalize voltage of 40V or more. Instead of the absolute max of 48V.

    SMA SB 3000, old BP panels.
  • VicVic Solar Expert Posts: 3,082 ✭✭✭✭
    new2PV wrote: »
    Well, if you put it that way, maybe that would be a good idea ... maybe I should look into a disonnecting combiner box that can support 2 dc breakers 120 amps each and mount it close to my batteries. I want this to be a safe system, but I dont see anything that would work on the site. I could just add another 250a breaker to the PDP. Now I have doubled my cable length even more. How about 1 fuse in one parallel string connection? Schneider makes a 250A fused combiner box, maybe this is the best solution, as it has a bus bar to combine 3 banks rated at the full 250 Amps.

    Hi new2,

    I inherently like the symmetry of adding a second 250 A breaker in the DC Conduit box ... BUT, this seems like a poor idea, as bet that these 250 A DC breakers are polarity sensitive, and, depending on the direction of the Fault current flow, the result may not be pretty, IMO.

    It seems to me that a single fuse in one battery string would provide protection from a Fault in either string, but this adds a slight asymmetry to the battery strings, BUT, this is probably mouse 'nuts', and probably would not be noticeable.

    The one issue with battery string fuses, is choosing the correct rating, and the type. One does not want any nuisance fuse blow events, as appropriate fuses are expensive. The fuse should be chosen based on the surge capability of the inverter. But if you have no large surging loads, like a well pump or air compressor (etc), then that could dictate a smaller fuse, and so on.

    It is good that you are trying to make your system as safe as possible. Hope others will offer input on your alternatives.
    Good Luck, Vic

    Off Grid - Two systems -- 4 SW+ 5548 Inverters, Surrette 4KS25 1280 AH [email protected], 11.1 KW STC PV, 4X MidNite Classic 150 w/ WBjrs, Beta KID on S-530s, MX-60s, MN Bkrs/Boxes.  25 KVA Polyphase Kubota diesel,  Honda Eu6500isa,  Eu3000is-es, Eu2000,  Eu1000 gensets.  Thanks Wind-Sun for this great Forum.
  • new2PVnew2PV Solar Expert Posts: 305 ✭✭
    Thanks for the explanation, so you saying I can't put another breaker since we don't know the direction of current flow based on which bank could short out?Only surge would be my 3 ton ac unit which is 43 amps..x 240 volts
    XW6848 inverter with 2 X mppt 60 150 CC , with Canadian solar 260Watt panels 2 x 3.5 kw array
  • inetdoginetdog Solar Expert Posts: 3,123 ✭✭✭✭
    You can put in another breaker if you can find one of the relatively small number of non-polarized ones. Fuses, for course, could care less about the current direction.

    The most common use of the polarized Midnite Solar breaker is as a panel disconnect, and in this case their recommendation is to install the breaker so that it works well as a switch with current flowing from the panel, but it will not work so well in the case of a short circuit in one string of panels.
    Compromises must be made.
    Also, a breaker failure event is much more likely to cause injury when it is used as a switch, compared to opening unattended for a short circuit.
    SMA SB 3000, old BP panels.
  • vtmapsvtmaps Solar Expert Posts: 3,738 ✭✭✭✭
    inetdog wrote: »
    You can put in another breaker if you can find one of the relatively small number of non-polarized ones. Fuses, for course, could care less about the current direction.

    All of the Midnite panel mount breakers are non-polarized. Only their din-rail breakers are polarized. This should work well for you because the larger sized breakers (which are what you want) are panel mount.

    --vtMaps
    4 X 235watt Samsung, Midnite ePanel, Outback VFX3524 FM60 & mate, 4 Interstate L16, trimetric, Honda eu2000i
  • VicVic Solar Expert Posts: 3,082 ✭✭✭✭
    vtmaps wrote: »

    All of the Midnite panel mount breakers are non-polarized. Only their din-rail breakers are polarized.
    --vtMaps

    Really,

    The way that I had read that relatively post from Robin on the MN Fourm, was that the Carling MNEDC breakers, in ratings of 5 - 100 Amps were THE ones that were non-polarized.

    Sure wish that these important facts were listed in the manufacturer's specs.

    Vic
    Off Grid - Two systems -- 4 SW+ 5548 Inverters, Surrette 4KS25 1280 AH [email protected], 11.1 KW STC PV, 4X MidNite Classic 150 w/ WBjrs, Beta KID on S-530s, MX-60s, MN Bkrs/Boxes.  25 KVA Polyphase Kubota diesel,  Honda Eu6500isa,  Eu3000is-es, Eu2000,  Eu1000 gensets.  Thanks Wind-Sun for this great Forum.
  • vtmapsvtmaps Solar Expert Posts: 3,738 ✭✭✭✭
    Vic wrote: »
    The way that I had read that relatively post from Robin on the MN Fourm, was that...

    There have been at least half dozen posts from Ryan or Robin on the Midnite forum about this. Here's the most recent (by Robin):
    Our panel mount breakers are non polarized, but the din rail breakers are not yet non polarized.

    --vtMaps
    4 X 235watt Samsung, Midnite ePanel, Outback VFX3524 FM60 & mate, 4 Interstate L16, trimetric, Honda eu2000i
  • new2PVnew2PV Solar Expert Posts: 305 ✭✭
    Are the MN breakers made by airpax or carliing?
    XW6848 inverter with 2 X mppt 60 150 CC , with Canadian solar 260Watt panels 2 x 3.5 kw array
  • VicVic Solar Expert Posts: 3,082 ✭✭✭✭
    vtmaps wrote: »
    There have been at least half dozen posts from Ryan or Robin on the Midnite forum about this. Here's the most recent (by Robin):
    --vtMaps

    Thanks vt for phrasing this SO succinctly.

    1. Sorry new2, that I was wrong about polarity sensitivity.

    2. All of the E-Frame breakers that I have purchased recently, have been Carling, and were ordered trough Distribution as MidNite breakers, although, see no special marking on them. Even those sold as for Schneider DC applications (usually for CCs) were Carling (80 and 100 A, E - Frame) and probably came from MN.

    Here is the link from the MN Solar site to the Specs for the MNEDC 125 breaker -- is it to the Carling data:
    http://www.midnitesolar.com/pdfs/Carling_E_Series.pdf

    Have used Airpax breakers E in the past for DC applications, mostly CC ins and outs. The design of this breaker is superior, IMO, but these breakers may be polarity sensitive.

    It is great that you are interested in designing a robust, safe system.

    Are unable to place the these two breakers in the Schneider Conduit box? Or is it that the inverter and that box (the PDP?) are located inside a structure?

    There could be a bit of a nit regarding the Listing of a box that you choose to place these battery breakers into, especially if it is repurposed If there is an Inspection, this would probably fly, but who knows. You probably would need a 3R type enclosure, and those might be a bit hard to find ... am not a Code guy.

    FWIW, Good Luck, Vic
    Off Grid - Two systems -- 4 SW+ 5548 Inverters, Surrette 4KS25 1280 AH [email protected], 11.1 KW STC PV, 4X MidNite Classic 150 w/ WBjrs, Beta KID on S-530s, MX-60s, MN Bkrs/Boxes.  25 KVA Polyphase Kubota diesel,  Honda Eu6500isa,  Eu3000is-es, Eu2000,  Eu1000 gensets.  Thanks Wind-Sun for this great Forum.
  • new2PVnew2PV Solar Expert Posts: 305 ✭✭
    The inverter will be inside the structure the batteries outside but sheltered, so you are correct on your assumptions. So are the E series breakers non polarized?, I;m still a bit unclear on that.
    XW6848 inverter with 2 X mppt 60 150 CC , with Canadian solar 260Watt panels 2 x 3.5 kw array
  • VicVic Solar Expert Posts: 3,082 ✭✭✭✭
    Hi new2,

    I wish I knew. It appears that Robin, THE Founder of MidNite Solar says, in many, many ... many quoteS from MidNite Forum PostS, that the Panel Mount breakers ARE non polarized. The MNEDC125 IS a Panel Mount breaker.

    But, as an Engineer, I would want to see this stated in writing from the Manufacturer, in their specs -- I cannot find such a statement there.

    I DO believe MidNite, and Robin, boB and the entire MidNite crew are trustworthy, so if Robin says it is so, I do believe it.

    Just make certain that you specify MidNite MNEDC125, or whatever you need, and that should do the job.

    If I were writing a PO for these items, I would specify, that they MUST be non-polarized, or not polarity sensitive, but this probably would cause consternation with your Supplier.

    It is astonishing to me, that this important information is not in the manufacturer's specs. Although, it all might have to do with the Safety Agency Listing process and Liability. Perhaps the manufacturer cannot say that it is not sensitive to polarity UNTIL it has been tested AND Listed/Accepted by some agency like ETL, UL, CSA, etc.

    I am certainly not in a position to pass judgment on weather these breakers are, indeed, not sensitive to polarity!

    For now, a single fuse should protect you, and perhaps, if you provided the ability to retrofit breakers later (when it might be noted in the Mfg specs), you could be OK.

    Realize that, with the disconnect function provided by a breaker, you could be able to Rest one string of batteries, to determine the SOC of that string by Resting voltage (after temperature compensation). For sealed batteries, this is a very good thing.

    FWIW, YMMV, and Good Luck, Vic
    Off Grid - Two systems -- 4 SW+ 5548 Inverters, Surrette 4KS25 1280 AH [email protected], 11.1 KW STC PV, 4X MidNite Classic 150 w/ WBjrs, Beta KID on S-530s, MX-60s, MN Bkrs/Boxes.  25 KVA Polyphase Kubota diesel,  Honda Eu6500isa,  Eu3000is-es, Eu2000,  Eu1000 gensets.  Thanks Wind-Sun for this great Forum.
  • new2PVnew2PV Solar Expert Posts: 305 ✭✭
    Since its going to be very difficult to get a 4/0 cable on a 125 amp breaker in a 3r disconnect, instead I am going with the Schneider fuse combiner box mounted inside a large 3R metal enclosure. Might seem a bit overkill here but Its my only solution that I can come up with. The combiner box is only IP20 rated.
    XW6848 inverter with 2 X mppt 60 150 CC , with Canadian solar 260Watt panels 2 x 3.5 kw array
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