48 V Switch Recommendation

[再生可能 エネルギー]

I try to use the best 48 V Switch for my Solar System, to easily disconnect the 48 V battery, the SCC controller, and the DC/AC inverter.

I found various information, and I would like to find some recommendation to dictate my choice:

- I noticed that many systems use the typical Blue Sea marine battery switch:

- I noticed also this video from David Poz recommending using DC circuit breakers

- I noticed also some other type of switches:

The Blue Sea switch seems easy to install, because the switch already has a casing with four holes for screws.
But a 16 cells LiFeP04 battery might top off at about 60 V which could too high for this switch,
primarily designed for Lead acid batteries.




The DC Circuit breaker might be safer but requires an additional box with a DIN rail




The other type of breakers in general don't get good recommendation





- Beside the nominal voltage of 48 V, my Solar system will be design for producing about 5 kW,
so those switches will need to handle at least 100 A, but I don't really plan to use them under load.

So what recommendation would you have for a 48 V switch?


- Also I would like to install a pre-load resistance for connecting the DC/AC inverter to the battery.

Is there any swich providing a temporay position to always force using a preload resistance?
Or do you have any recommendation, like a push button, to connect a preload resistance.

 

[rmaddy]

See the following for good information on setting up a switch with a pre-charge resistor. The real trick is first finding a switch that can handle the 60V. Also note that the pre-charge resistor should only affect the inverter. It should not affect other components such as the solar charge controller or a DC fuse box, etc.

Inverter Disconnect Switch with Precharge

To get the paper, click on the orange button at the top of this page. This circuit is designed as a disconnect switch that allows the user to pre-charge the inverter capacitors before turning the switch completely on. 26 June 2020 update: At...

diysolarforum.com

 

[再生可能 エネルギー]

See the following for good information on setting up a switch with a pre-charge resistor. The real trick is first finding a switch that can handle the 60V. Also note that the pre-charge resistor should only affect the inverter. It should not affect other components such as the solar charge controller or a DC fuse box, etc.

Inverter Disconnect Switch with Precharge

To get the paper, click on the orange button at the top of this page. This circuit is designed as a disconnect switch that allows the user to pre-charge the inverter capacitors before turning the switch completely on. 26 June 2020 update: At...

diysolarforum.com

Thank you for your reply, regarding pre-charge resistor.

Does any one has recommendation for a 48 V switch, between:

- The Blue Sea switch which seems easy to install, because the switch already has a casing with four holes for screws.
But a 16 cells LiFeP04 battery might top off at about 60 V which could too high for this switch,
primarily designed for Lead acid batteries.

- The DC Circuit breaker might be safer but requires an additional box with a DIN rail.

- The other type of breakers combining in general a switch.

 

[rmaddy]

Blue Sea Systems has stated that the 48V Blue Sea switch is only to be used up to 48V so that's not an option.

 

[SniperX]

About none of those standard switches are good for more than 48V. I bought one that said it was good for 60 (that looked just like the 48Vs), but when I opened it to connect the wires, it said 50V max, molded right into the case. I've done a lot of digging on Solar sites and electrical catalogs (I'm an EE, and so have a pretty good idea on sourcing) but even I got an education that there are not a lot of 60VDC switches (don't confuse with AC which are much easier and cheaper). I have only found two, neither cheap, that fit the bill. I have both, one as internal cutoff for casual maintenance / configuration work, and another for my primary area up on the roof (of my mobile workshop/trailer/RV)

They are as follows.

1) purpose built solar panel cutoff switch, such as my roof mount one: https://www.amazon.com/gp/product/B07NVXNJBL/ref=ppx_yo_dt_b_search_asin_title?ie=UTF8&psc=1

2) my internal rig cutoff switch like this: https://www.amazon.com/gp/product/B09XGXD7CV/ref=ppx_yo_dt_b_search_asin_title?ie=UTF8&th=1

Of course, you can go the cheap DC miniature breaker route, which also gives you a "free" breaker, and mount it on a din rail or box. That is by far the cheapest DC route, but note, if you're being a stickler, the mechanical design of these, or any breakers, of for the switch to be physically flipped by over-current-mechanism, not, the other way around (fingers flipping from the external lever end). Not a big deal for lite use if you get a good quality one, but like a baseball bat, you can flip it around and use it the other way, but it won't hold up as long.

What I want, but haven't found at all, is any high current DC SPDT (or DPDT) switch. Note one that wasn't pushing $500 anyway.

If anyone knows otherwise, I'd love to hear it.


Hope that helps someone.

Roger

I don't mean to hijack this thread, but can you post a picture of your setup? If you could get a DC SPDT switch and money was not a hindrance, what would you buy? I am researching this part of my build and for all I have invested, saving money here is not going to make that much of a difference over peace of mind. Really appreciate your links and answers.

 

[SniperX]

Also, heads up to the OP, but look at your busbars too. Many are rated for 48V but you know those batteries charge higher than 48V. I had to get a victron busbar rated at 60V because I was not comfortable with the max 48V.

 

[Leeds]

Also, heads up to the OP, but look at your busbars too. Many are rated for 48V but you know those batteries charge higher than 48V. I had to get a victron busbar rated at 60V because I was not comfortable with the max 48V.

Forgive me if this is a silly question, but what is a voltage rating in the context of a busbar?
I completely get that they need current ratings to ensure that they aren't undersized causing them to overheat. But what does a "voltage rating" mean on a piece of metal that has a zero (or at least entirely negligible) voltage drop across it?
To put it another way, wow would a buss bar "know" it was in a 60v system vs a 48v system if the voltage drop across it is 0.0001 volts?

 

[SniperX]

Hmmm, I put links to both my switches in my original comment. Does this site auto-strip them out?

I was wondering about this: "What I want, but haven't found at all, is any high current DC SPDT (or DPDT) switch. Note one that wasn't pushing $500 anyway."
Did you find one but the price was too high? That was what I was asking. I am appreciative of your links, and I did go take a look and will be getting one for my Rv. Just curious about the high-dollar ones you referenced. I take it you have found one but it was around $500 or more so not on your list. Maybe I read that wrong.

 

[Hedges]

To put it another way, wow would a buss bar "know" it was in a 60v system vs a 48v system if the voltage drop across it is 0.0001 volts?

Blue Sea Systems has stated that the 48V Blue Sea switch is only to be used up to 48V so that's not an option.

I don't think the switch or busbar would know. Voltage would have to be much higher to jump across or cause dielectric breakdown.
But there are safety rules regarding what voltages are to be accessible to the Great Unwashed.
Compliant higher voltage hardware is tested to prevent access to live terminals, except by means of tools.

I think the switch and busbar would conduct current, and hold off voltage, just fine. But wouldn't comply with regulations.

 

[Leeds]

I don't think the switch or busbar would know. Voltage would have to be much higher to jump across or cause dielectric breakdown.
But there are safety rules regarding what voltages are to be accessible to the Great Unwashed.
Compliant higher voltage hardware is tested to prevent access to live terminals, except by means of tools.

I think the switch and busbar would conduct current, and hold off voltage, just fine. But wouldn't comply with regulations.

I wouldn't lump switches in with busbars. Switches absolutely have a voltage rating as they need to accommodate for the greater possibility/inevitability of arcing at higher voltages.

But yeah, other than a silly sticker from a manufacturer I don't think there can be a difference between a "48v" bar or a "60v."

 

[SniperX]

Hi, no, you read that right. I ran across some industrial switch, which when bought in quantity, was $450. It was so out of line that I didn't make a note of who, though I'll say in general I tend to search DigiKey and Mouser a lot for such things. Also, solar disconnect switches are under 100 on amazon. I just spent 30 minutes trying to find it again and couldnt, but have to get back to work now Sorry.

Thanks for looking. Sorry it was a time-waster.

 

[SniperX]

Forgive me if this is a silly question, but what is a voltage rating in the context of a busbar?
I completely get that they need current ratings to ensure that they aren't undersized causing them to overheat. But what does a "voltage rating" mean on a piece of metal that has a zero (or at least entirely negligible) voltage drop across it?
To put it another way, wow would a buss bar "know" it was in a 60v system vs a 48v system if the voltage drop across it is 0.0001 volts?

I have Been looking for the place that I saw which made me search for that Victron busbar and I found it. Go to this video by David Poz and then the first comment is by a person named tt smith. He has A LOT to say about that high voltage and I think he makes some seriously valid points. One is the busbar. I will attach the link to the video and then you can see what you think.

 

[rhino]

Thanks for looking. Sorry it was a time-waster.

I just received a 2 pole Noark 250A and 150A DC breakers shipped from within the US. Received in less than 2 weeks. Was under $500 total for both. Here is spec sheet: https://na.noark-electric.com/wp-content/uploads/MCCB-Datasheet-NOARK.pdf... Haven't opened the box fully yet to even check them but will post message when I do..

 

[SniperX]

I just received a 2 pole Noark 250A and 150A DC breakers shipped from within the US. Received in less than 2 weeks. Was under $500 total for both. Here is spec sheet: https://na.noark-electric.com/wp-content/uploads/MCCB-Datasheet-NOARK.pdf... Haven't opened the box fully yet to even check them but will post message when I do..

When you get a chance, can you see what company you ordered from on the box when you open it? Does not have to be immediately, but I would really like to find a good source.

 

[rhino]

When you get a chance, can you see what company you ordered from on the box when you open it? Does not have to be immediately, but I would really like to find a good source.

Noark North America told me to order from https://www.wolfautomation.com/manufacturer/noark_electric. They do not list the MCCB on the website so you have to look at spec sheet and provide them with the part number to get a quote. One I got was M1S150T22L which was in stock somewhere in North America but I have a question I am waiting for an answer on regarding the interrupting capacity. It is rated at 20kA at 500VDC so I am asking if they have a value for 60VDC.

 

[chess-equality]

Noark North America told me to order from https://www.wolfautomation.com/manufacturer/noark_electric. They do not list the MCCB on the website so you have to look at spec sheet and provide them with the part number to get a quote. One I got was M1S150T22L which was in stock somewhere in North America but I have a question I am waiting for an answer on regarding the interrupting capacity. It is rated at 20kA at 500VDC so I am asking if they have a value for 60VDC.

It's printed on the front. Example:

https://www.tro.com.au/Noark-Moulded-Case-Circuit-Breaker-2-Pole-500V-DC-250A

25kA

It's in AUD.

 

[Hedges]

I wouldn't lump switches in with busbars. Switches absolutely have a voltage rating as they need to accommodate for the greater possibility/inevitability of arcing at higher voltages.

But yeah, other than a silly sticker from a manufacturer I don't think there can be a difference between a "48v" bar or a "60v."

To interrupt current can require special design. Don't open those switches under load.
Interrupting DC vs. AC are different. I've seen switches rated 600VAC and 24VDC (actually, DC voltage rating varies with current.)

To hold off voltage when already open requires sufficient gap. In air, lowest voltage of Paschen curve is 370V.
For other gasses like helium it is lower.

The plastic dielectric could start leaking some current and eventually fail. At higher voltages, or smaller distances. Dirt/dust plus humidity also can require more distance, and perhaps a convoluted shape to avoid falling dust making a coating over the entire distance.

I think the 48V max voltage ratings are based on what is relatively touch-safe vs. considered a human hazard, not what voltage would suddenly jump across an already open switch. I think it would function just as well at 60V, 80V, 100V. Again NOT for opening under load. Probably not rated for it because 1) Didn't pay UL to do the test, and 2) Didn't design it to prevent the mechanical test finger from reaching live parts.

 

[SniperX]

Noark North America told me to order from https://www.wolfautomation.com/manufacturer/noark_electric. They do not list the MCCB on the website so you have to look at spec sheet and provide them with the part number to get a quote. One I got was M1S150T22L which was in stock somewhere in North America but I have a question I am waiting for an answer on regarding the interrupting capacity. It is rated at 20kA at 500VDC so I am asking if they have a value for 60VDC.

Just realized they were in Queensland AUS! My camper manufacturer (SniperX) lives there. I bet he could find me some and send it over if I can't find them here in the U.S.

 

[JonL]

I am no expert by any means, so I just thought I’d point this out since I saw it on another video. Around five minutes and 25 seconds into the video they talk about disconnect switches, and eventually a Victron solution!
It would be interesting to see what people think, since I think this is relatively new. ?

 

[rhino]

I am no expert by any means, so I just thought I’d point this out since I saw it on another video. Around five minutes and 25 seconds into the video they talk about disconnect switches, and eventually a Victron solution!
It would be interesting to see what people think, since I think this is relatively new. ?

That is just the same DC breaker Midnite sells which is a rebranded Carling Tech breaker.