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  • Looking for DC switch

    Where do I find a 3 DC Switches?

    I’m looking for a DC switch for no more than 30 amps and max of 45 Volts DC just like this
    91333DF4-DACE-4CBE-983D-31A3D06FDE4B.png
    This switch is made by Blue Sea https://www.bluesea.com/products/909...20_240V_AC_65A, but unfortunately its rated for AC Power, 65 Amps 120 / 240 volts.

    I want to take a single input and send it to a choice of a 30 amp breaker or a 15 amp breaker. THe positions will be 15 AMps, 30 amps, off. This will all be whether my suitcase panels I attach to my RV are 4 in series for the lower Amp breaker, or in parallel for the night amp breaker.

    I think the terminology of the switch is 3P4T (3 Position 4 THrow), but that’s not producing any DC results, if it shows the switch I want, rated for AC only.
    Attached Files

  • #2
    Those multi throw switches commonly use rotary wafers, rated in mA. Getting something in DC voltage and amp ratings is going to be tough. You may have to make your own.
    Diode steering might work, but you would loose power in the diodes (as heat, .7V 30A is 21 watts into a beefy heatsink)
    Powerfab top of pole PV mount (2) | Listeroid 6/1 w/st5 gen head | XW6048 inverter/chgr | Iota 48V/15A charger | Morningstar 60A MPPT | 48V, 800A NiFe Battery (in series)| 15, Evergreen 205w "12V" PV array on pole | Midnight ePanel | Grundfos 10 SO5-9 with 3 wire Franklin Electric motor (1/2hp 240V 1ph ) on a timer for 3 hr noontime run - Runs off PV ||
    || Midnight Classic 200 | 10, Evergreen 200w in a 160VOC array ||
    || VEC1093 12V Charger | Maha C401 aa/aaa Charger | SureSine | Sunsaver MPPT 15A

    solar: http://tinyurl.com/LMR-Solar
    gen: http://tinyurl.com/LMR-Lister

    Comment


    • #3
      Will you have to switch with power applied and current flowing? No? If you can be certain that you never close or open with current flowing, then an AC switch will do the job. The main difference is that DC switches can handle the arc that forms when relay contacts open.

      If you need to switch with power flowing, consider using relays. You may need more than one, and build a small box to house them. There are many high-current relays available for the automobile industry that are rated 50VDC and 30A.

      Here's the Schneider Electric relay catalog:
      https://download.schneider-electric....Ref=8501CT1003
      Omron, TE Connectivity and others also make quality DC relays.
      7kW Roof PV, APsystems QS1 micros, Nissan Leaf EV

      Comment


      • #4
        Well, the arcing in DC switches may explain I why its not available. Blue Sea makes a battery switch I could get two for and do what I want, but they are big. Since arcing is a problem and my three panels in series already arc when I do an amp check, than I really do not want any switch I can find unless its rated for it.

        Relays may work, but will take some thought on my part and will take some thought on my part so whatever chain of relays I have are open with no power.

        EDIT:
        Just got his EMail from Blue Sea and the switch will work for DC:

        ”Thank you for the question. We have been told by Krause and Naimer the maker of the Rotary switch that is will work for DC also.
        Please ask if you have any additional questions.
        Best Regards,

        Blue Sea Systems Tech Support”
        Last edited by chrisski; 10-19-2020, 11:42 PM.

        Comment


        • #5
          Originally posted by chrisski View Post
          ....”Thank you for the question. We have been told by Krause and Naimer the maker of the Rotary switch that is will work for DC also.....
          Best find out if it will work at the DC voltage & amps it will be running at. 32v is often the limit for many marine and automotive gear.

          Powerfab top of pole PV mount (2) | Listeroid 6/1 w/st5 gen head | XW6048 inverter/chgr | Iota 48V/15A charger | Morningstar 60A MPPT | 48V, 800A NiFe Battery (in series)| 15, Evergreen 205w "12V" PV array on pole | Midnight ePanel | Grundfos 10 SO5-9 with 3 wire Franklin Electric motor (1/2hp 240V 1ph ) on a timer for 3 hr noontime run - Runs off PV ||
          || Midnight Classic 200 | 10, Evergreen 200w in a 160VOC array ||
          || VEC1093 12V Charger | Maha C401 aa/aaa Charger | SureSine | Sunsaver MPPT 15A

          solar: http://tinyurl.com/LMR-Solar
          gen: http://tinyurl.com/LMR-Lister

          Comment


          • #6
            Originally posted by Mike90250 View Post

            Best find out if it will work at the DC voltage & amps it will be running at. 32v is often the limit for many marine and automotive gear.
            I still won’t install it without asking Krause and Naimer myself. I had asked about 45 Volts and 30 amps to Blue Sea, but if they are not making it, I’m going to want to hear the DC specs from the company itself directly.

            This probably would not have worried me had I not seen three 100 watt panels in series arc.

            Comment


            • #7
              While not a traditional switch, per se, Midnite Solar and Outback DC circuit breakers are rated for higher voltage (150 and 300 Vdc,) and switching while current is flowing.
              Last edited by littleharbor; 10-20-2020, 08:24 AM.
              2.2kw Suntech mono, Classic 200, NEW Trace SW4024

              Comment


              • #8
                The Krause and Naimer switch sounds like a good solution.

                As a side: I have a DC light in my shed. I switch DC from a battery to the light with a simple mechanical switch. To protect the contacts and make the switch last longer, I put an RC snubber across the switch. RC snubbers or RCD snubbers SHOULD be adequate to make any AC switch safe switching DC. The capacitor needs to be large to handle the surge current and also large enough value to absorb one-time current surges from stored energy in the wire, without excessive voltage excursions. The resistor can be relatively small because you don't switch often, and even then, power resistors are really cheap. For my 2A/12V light, the snubber was tiny and cheap, and the voltage spike never goes over 20V.

                I'm not suggesting this as the best solution to your problem. It's more an academic solution. To learn more, here is one of many possible references:
                https://www.daycounter.com/Calculato...lculator.phtml
                7kW Roof PV, APsystems QS1 micros, Nissan Leaf EV

                Comment


                • #9
                  If you are going to design something, consider DC solid state switches/relay. They too, require a snubber circuit for each switch to prevent it from voltage spikes, but once you design one, and get a kit of parts, probably cheaper by the dozen !
                  Beware - many knockoffs of major brands exist, only buy from reputable mfgs
                  https://www.digikey.com/en/products/...AEBlFAlEBdAvkA
                  Powerfab top of pole PV mount (2) | Listeroid 6/1 w/st5 gen head | XW6048 inverter/chgr | Iota 48V/15A charger | Morningstar 60A MPPT | 48V, 800A NiFe Battery (in series)| 15, Evergreen 205w "12V" PV array on pole | Midnight ePanel | Grundfos 10 SO5-9 with 3 wire Franklin Electric motor (1/2hp 240V 1ph ) on a timer for 3 hr noontime run - Runs off PV ||
                  || Midnight Classic 200 | 10, Evergreen 200w in a 160VOC array ||
                  || VEC1093 12V Charger | Maha C401 aa/aaa Charger | SureSine | Sunsaver MPPT 15A

                  solar: http://tinyurl.com/LMR-Solar
                  gen: http://tinyurl.com/LMR-Lister

                  Comment


                  • #10
                    Originally posted by chrisski View Post
                    Where do I find a 3 DC Switches?

                    I’m looking for a DC switch for no more than 30 amps and max of 45 Volts DC just like this
                    91333DF4-DACE-4CBE-983D-31A3D06FDE4B.png
                    This switch is made by Blue Sea https://www.bluesea.com/products/909...20_240V_AC_65A, but unfortunately its rated for AC Power, 65 Amps 120 / 240 volts.

                    I want to take a single input and send it to a choice of a 30 amp breaker or a 15 amp breaker. THe positions will be 15 AMps, 30 amps, off. This will all be whether my suitcase panels I attach to my RV are 4 in series for the lower Amp breaker, or in parallel for the night amp breaker.

                    I think the terminology of the switch is 3P4T (3 Position 4 THrow), but that’s not producing any DC results, if it shows the switch I want, rated for AC only.
                    Look at these. They are rated for this usage

                    https://www.industrialcontroldirect....bq6btoijd09a56

                    Andy

                    Comment


                    • #11
                      Originally posted by PVAndy View Post

                      Look at these. They are rated for this usage

                      https://www.industrialcontroldirect....bq6btoijd09a56

                      Andy
                      Thanks. Pretty expensive.

                      I am going to try out the panels in parallel and not worry about putting them in series to start. Turns out this project is bit harder than I thought. Just building, wiring and crimping the combiner / circuit breaker boxes for these panels is taking 3 days.

                      Comment

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