ABYC disconnect for propulsion battery

ABYC says that there must be a disconnect that simultaneously breaks the positive and the negative conductors. What are people using for this. Elco reverences this requirement on their video on installing batteries for propulsion and then shows a single conductor mushroom switch . Double pole switches I have found that will handle 200 vdc and 300 amps are BIG and expensive. I have seen nothing like this on any electric boats. Please enlighten me

 

What about solar products? The amperage is pretty high is all...

Hopefully someone has a better answer!

Northern Arizona Wind and Sun may be a resource..

 

It is a BIG knife switch...Still the go to on things like SS1/2...and better than a bus bar and axe. For 240V/300 amps cost of a box is ~$1200.00.

Edit to add...The Elco video could be showing a custom Pilla Electrical cut-off or similar. Founded by my wife's grandfather and still operated by her uncles, they do custom power cut-off switches. They are pretty ubiquitous in the US (i.e. NASA, Disney, marinas, most gasoline stations, etc) because they were one of the first (circa 1964/5) to have all the certs (UL, NEMA, NFPA, NYC, etc). P.S. I have nothing to do with the website, so I apologize.

http://pillaelectricalproducts.com/PillaX.htm

Edit: noticed I missed a zero 120/1200

 

I know the Rincon high voltage disconnect switches are popular with EV conversions, but I don’t think they offer a DPDT version.

I use a DPDT Blue Seas switch that will handle high amperage, but not voltage which isn’t a problem for me as my system is only 24v.

The main reason I went with DPDT was so I could use the switches long studs as a bus “bar” to supply power to and pull power from the battery bank which keeps things tidy and reduces the need for more connections, extra wiring, etc..

 

DPDT? Double Throw means a 3-position switch, On 1-Off-On 2. I would expect what is required is a DPST.

 

Whoops, I got my switches switched up!

Or I should say my “smart” device did because I recently posted about DPDT switches somewhere else and we’ll you know….

Thanks for the catch jehardiman!

 

No worries. DPDT switches are common in the Marine Industry for battery bank selectors....Off-House-Start typically. You could easily set one up for Off-House-Propulsion which would meet the requirement to disconnect both the positive and negative to/from the propulsion battery/motor.

 

Everything high voltage/amperage is going to be big and expensive and if you look for manual switches also rare, the land based EV industry uses contactors and FET's for mobile applications. Manual switches are usually found in HVDC distribution like solar array systems, or light rail.
Emergency switches (push button style) do not have to be double pole.

High voltage boats are uncommon, most systems are 48V max. and a waterproof DPST manual switch rated 48V 500A continuous is under 200$.

 

48v at 250 amps is 12 kw ABYC limits 4/0 cable to under 250 amps for propulsion use. Some people gang multiple motors for more power at <250 amps per motor. much more common to increase voltage for larger motors. This is the switch I sourced.

 

How do you make those connections without solder? They don't look like screw terminals..

 

Just to reiterate, 200 V and 300 A is 60 kVA....that is like the total power draw of 3 large houses that use electric heat. It is not a "boat" electrical fitting, unless your "boat" is a mega yacht. Almost anything that size is custom order. Also I noticed I left a zero off my first post....a simple disconnect box is ~$1200.00...

 

The screw terminals are extra, they look like this ABB OZXA-800 https://www.northeastparts.com/products/abb-ozxa-800 and of course the cables need sleeves.
Also extra for this model are the shaft and key to operate the switch.
The unit also contains fuses, if those are missing he has to add 10kA ones.
This model is only IP20, so he has to add a waterproof DIN rail box with the appropriate size cable glands to mount it in.
Of course ABB also makes this switches in IP68 and IP69k with integrated handles.

He uses it for a traction application to separate the traction battery from the controller/charger, not for a house supply. His boat probably needs a 60kW motor and I understand the standard requires him to have a manual isolation switch, probably to insure safe working on the rest of the circuit (motor controller and charger).

 

As I understand it the pictured switch will not be able to cut off two poles (plus and minus) under load because the danger of drawing electric arcs. . Dependend of the wiring (according to the first circuit diagram at the lable) the switch is thought to be used as two switches in series at the same pole to prevent arcs under load.
At a different wiring you can use it for two poles but only cutting the connections that are already currentless.

 

Would you expound on that?

I wondered the same thing, but then how does it get rated as dpst? And how do you arrive at the assertion?

It cannot have contacts, that much I understand..

 

I will try in my poor English.
Some switches are called in German "Batterie-Trennschalter" (literal "battery disconnect switch"). They are used to disconnect the battery when no load (or only a insignificant rest of loads) are connected to the DC grid on board. They are usually rated with a certain value of voltage and a certain value of amperage. If your active electric loads on board are drawing current at the limit of the rated vaues, the switch will become warmer because it represents a certain Ohm's resistance but should not get hot, beeing damaged or destroyed.

But you should not use this kind of switch to cut off a electric current flowing to supply a relevant load. Open a switch means to open a certain gap between two metal pieces (often copper) which were in contact before. At a voltage of more than 12 V DC you may draw an electric arc (Lichtbogen) may be only for a fraction of a second cause the gap widening will quentch the arc. At a voltage of 30 V or more DC the arc is able to stay depending on certain conditions. The current is lower but flowing the switch will be damaged or destroyed.

To prevent this dangerous effect, there are "Leistungs-Trennschalter" (free translation: "switches for cutting strong currents"). These consist of two switches in one unit with only one actuator to open both at the same time. that means there are one or two centimeters distance and isolating parts between the "endpoints" of the voltage. Even a very small gap between both pairs of switching parts will not lead to electric arcs.

I hope this will be understandable.