DC Disconnect with 6 poles ( for lack of better term)

[aelectricalman]

I am looking for a single disconnect that will shut down up to 6 circuits at one time. It must be DC rated and can not depend on AC circuit to close or open a coil. Has anyone every seen such a beast?

 

[Besoeker]

I am looking for a single disconnect that will shut down up to 6 circuits at one time. It must be DC rated and can not depend on AC circuit to close or open a coil. Has anyone every seen such a beast?

Got any information on voltage and currents?
Disconnect off load or on load?
Type of load?

 

[aelectricalman]

Got any information on voltage and currents?
Disconnect off load or on load?
Type of load?

The voltage is 600V max
The current is 12A per string (leg) and there would be 6 of them.
Not sure what your asking by on load or off load.
Its a solar PV system and we are required to have a DC disconnect on the roof of the building to take the 6 circuits to the inverters, whcih are mounted 2 stories down

 

[jbelectric777]

sounds like something you would need in a power company sub station. the 6 pole switch is probably a contactor because you mention a coil. you can buy a 6 pole or 2 3 pole magnetic contactors (be careful these are contactors not motor controllers, there are a big difference, MC has thermal overload protection) i think i remember the contactor coils being dual rated (AC OR DC) call your local supplier and talk to inside sales, they can best help you.

 

[aelectricalman]

sounds like something you would need in a power company sub station. the 6 pole switch is probably a contactor because you mention a coil. you can buy a 6 pole or 2 3 pole magnetic contactors (be careful these are contactors not motor controllers, there are a big difference, MC has thermal overload protection) i think i remember the contactor coils being dual rated (AC OR DC) call your local supplier and talk to inside sales, they can best help you.

Cant use a contactor.

 

[mxslick]

Why not use a standard 3-pole disconnect (rated for DC loads of 12 amps which I'm sure would be no big deal) and open only the positive (or negative) leg of each circuit? (If the DC side has a grounded leg, open whichever leg is NOT grounded.)

I see no reason to open both legs of a DC circuit in this case.

 

[jbelectric777]

yea, use a 30 amp disconnect 3 pole, why use 6

 

[iwire]

I see no reason to open both legs of a DC circuit in this case.

How could we possibly know this from the info given?

We can't.


Depending on the load a rotary disconect switch may be what you need.

 

[jbelectric777]

you didnt say it was a spv,12 amps load, can u paralell them and use a 3 pole, i dont do them but inspected a lot of em in NJ 80% of 30 is 24

 

[SG-1]

Will something primitive like a knife switch work ?

http://www.filnor.com/html/products/knife-switch.php

 

[jbelectric777]

thats all they use now, get what ya need raintight or indoor

 

[ControlFreak]

I know Bussmann makes 6 pole disconnect switches, and I was going to send you a link to their disconnect catalog but see this:


http://www.cooperbussmann.com/pdf/8c2d6f93-8905-4e7a-8775-9b7beae3e385.pdf

This was on the front page of the Bussmann website.

http://www.cooperbussmann.com/

 

[aelectricalman]

yea, use a 30 amp disconnect 3 pole, why use 6

I could parellel them but I have to have six circuits for six inverters. Do you see any problems with that app. I have to uncombine them after the switch. I guess as long as the resistance at the other end remains constant it would work. Is it legal?

 

[iwire]

I see no way you could parallel them.

 

[david luchini]

The voltage is 600V max
The current is 12A per string (leg) and there would be 6 of them.
Not sure what your asking by on load or off load.
Its a solar PV system and we are required to have a DC disconnect on the roof of the building to take the 6 circuits to the inverters, whcih are mounted 2 stories down

Why not use a fused string combiner to join all the strings on the roof, and run only two conductors down the inverter (inverters?) Then you could use a two pole disconnect.

 

[aelectricalman]

We have 6 inverters each needing a positive and a negative. Thats the kicker.

 

[aelectricalman]

The inspector wants the DC side of the system to be on 1 disconnect for the purpose of giving the fire dept. the luxury of shutting the system down with one handle. This seems impossible! Normally we would have 1 big inverter but not in this case. Any suggestions.

 

[aelectricalman]

I know Bussmann makes 6 pole disconnect switches, and I was going to send you a link to their disconnect catalog but see this:


http://www.cooperbussmann.com/pdf/8c2d6f93-8905-4e7a-8775-9b7beae3e385.pdf

This was on the front page of the Bussmann website.

http://www.cooperbussmann.com/

The only problem with this is it combines the outputs. We cant use a combiner box on this app.

 

[david luchini]

We have 6 inverters each needing a positive and a negative. Thats the kicker.

One inverter per string? I've never seen it done that way. What's the inverter ratings?

 

[eprice]

The inspector wants the DC side of the system to be on 1 disconnect for the purpose of giving the fire dept. the luxury of shutting the system down with one handle.

Is there a local amendment to back up the inspector's wish? I think the disconnect you are talking about is the one covered in 690.13 and 690.14. 690.14(C)(4) allows 6 switches for this disconnect. Why should this disconnect be treated more restrictively than a service disconnect?