DC disconnect

[Norman Dowds]

A DC disconnect is quite expensive . For a small system with a small
inverter ( <1000 w ) could one not build a custome disconnect from din rail
etc . Your comments ....

 

[Robert Morein]

A DC disconnect is quite expensive . For a small system with a small
inverter ( <1000 w ) could one not build a custome disconnect from din rail
etc . Your comments ....

Take a look at
http://www.jcwhitney.com/autoparts/ProductDisplay/s-10101/p-1027/c-10101

 

[m II]

Take a look at

http://www.jcwhitney.com/autoparts/ProductDisplay/s-10101/p-1027/c-10101

Those should be called isolating switches. I get the feeling that they would
become something that resembles welding practice if you ever tried actually
switching the amperages they are showing.

They may work well for making sure you don't blow yourself up when working
on some equipment, but they sure as heck won't work as a real load switching
device. IF the equipment is already turned off, fine..it's just insurance,
but nothing else.




mike

 

[Robert Morein]

Those should be called isolating switches. I get the feeling that they would
become something that resembles welding practice if you ever tried actually
switching the amperages they are showing.

They may work well for making sure you don't blow yourself up when working
on some equipment, but they sure as heck won't work as a real load switching
device. IF the equipment is already turned off, fine..it's just insurance,
but nothing else.

I agree. May still be useful either for emergency, or by switching off the
inverter first.

 

[Norman Dowds]

Thanks for the offer . Could you please provide some descirptive information
.. My circuit diagram calls for a 175 amp main disconnect which isolates the
battery from the inverter , 3 30amp breakers isolate in turn the PV array ,
Charge Regulator , and DC load distribution panel . I will also need a
ground buss and a negative buss to which I will attach a meter shunt .

Is your box a shell into which these DC breakers etc could mount ? Could you
describe what was mounted previously and approximate size .

 

[Norman Dowds]

The device to which I refer is a panel containing all the necessary dc
isolation equipment , busses , shunts etc . For example as produced by
OutBack or Trace . I think the item to which you refer is simply a switch
which if it would work as spec'd could be mounted inline with a T class
fuse. However , there is much more functionality than inverter isolation in
a DC disconnect . Outback provides a good description of this genric system
component .

 

[Robert Morein]

I have an Outback DC disconnect, which I chose for code compliance.
My own observation of what it is is this:
It is a huge, almost completely empty box, twice the size of the Xantrex
SW+
It has one switch in it.
It cost $400, which is a helluva lot for one switch.

 

[jim w]

DC switchs are a lot harder to make than AC switches, for obvious reasons.

- jim

 

[[email protected]]

I can give you a free DC disconnect from a large battery bank. It is
two pieces with one sliding into another. You will pay shipping etc.

i

Works fine for disconnecting with no load. But disconnecting DC under
load is pretty tricky. You need some sort of arc suppression.

The rerason AC is so much easier to switch is both current and voltage
are zero one every 120th of a second on 60 hz AC.

 

[Norman Dowds]

The enclosures to which you refer are AC rated . The application is DC and
not one of power distribution but rather power source isolation . It is my
opinion that the small breakers will din mount but not so a main breaker of
say 200amps as would be the case if planing to migrate to AC via adding an
inverter ( which for myself is the case ) .

I have now decided to build the box from basic components of the type sold
by Square D .