Dc breaker with resistor?

[Scph9002]

In dc connectors with large inrush current you can add a resistor that make connection before the conductor to prevent the spark.

There does not seem to be a similar thing for dc breaker and for a good reason I assume. But what is that reason? A dc breaker that breaks dc line first while still having a resistor in line until you fully break the connection should raise voltage up to close to open voltage values and when that breaks no arc happens. I know that even ac breakers can break very high dc voltages no problem as long as they are in close to max open voltage but if they anywhere near short circuit they arc like crazy.

Or?

 

[DIYrich]

Breaker opens on current, not voltage. If it doesn’t open right away. It will never open. Current declines as inverter charges.

 

[DVD]

Actually there are XT90 connectors that are “no spark”. As the connection is initially broken, there is a second contact that has a resistor back to the first contact so that most of the voltage is dropped when the final disconnect occurs - hence no high current arc.
These often have a green band to signify it.

There’s little reason a DC breaker could not employ a similar operation.

 

[MattiFin]

In dc connectors with large inrush current you can add a resistor that make connection before the conductor to prevent the spark.

There does not seem to be a similar thing for dc breaker and for a good reason I assume. But what is that reason? A dc breaker that breaks dc line first while still having a resistor in line until you fully break the connection should raise voltage up to close to open voltage values and when that breaks no arc happens. I know that even ac breakers can break very high dc voltages no problem as long as they are in close to max open voltage but if they anywhere near short circuit they arc like crazy.

Or?

Actually there are XT90 connectors that are “no spark”. As the connection is initially broken, there is a second contact that has a resistor back to the first contact so that most of the voltage is dropped when the final disconnect occurs - hence no high current arc.
These often have a green band to signify it.

There’s little reason a DC breaker could not employ a similar operation.

Doesnt't work like that when breaking contact. XT90 no-spark connectors also work only during connect but have very little to no effect on disconnect.

Contacts arc on connect because of the large inrush current created when inverter or speed controller input capacitors are charged.
On disconnect the contacts arc only if there is a large current flowing trough the contacts. To prevent sparking there would need to be temporary alternative route for the current to flow so that contacts can open with small current/voltage over them. Can't use straightforward resistor because then there would be similarly large current flowing trough the resistor and you would need to break that too.

In theory you can use capacitor across the contacts on DC system and it would prevent arcing on disconnect(switch opens, current flows trough the capacitor and fades to 0 and by that time contacts are fully open. Real-life is more complicated and this is not typically used.
Most notable use of capacitor across contacts would be old-school ignition with points. Capacitor over the contacts is pretty much vital in these systems, otherwise the contacts burn up in short time.

 

[DVD]

Sorry to disagree. The XT descriptions are pretty clear. It’s also commonly understood that arcing is a disconnect phenomenon.

 

[Scph9002]

It would be easy to test this. Worst (best?) case scenario to produce an disconnect arc would be to put your solar array into direct short circuit during full sun. Pv pos and neg connected directly to each other and then opened. Basically max amp 0 voltage closed circuit. Opening this curcuit (breaking current flow) will produce maximum arcing.

In paralell with the pv pos and pv neg you use a (high or low no idea if it matters) ohm resistor that keep the circuit closed when the pv pos and neg is opened and then furthering opening the connection will physically break the resistors connection.

This will or will not produce an significant arc?

 

[Scph9002]

See crude diagram :>

Breaking procedure 1 then 2 then lastly 3 where resistor is disconnected last.

 

[efficientPV]

this will definitely not help. No experiments are needed. This is well documented science. The bible of things which go arc in the night is GASEOUS CONDUCTORS by James Dillon Cobine. The handiest book I have. I actually have a couple books from his private library. You want something to either short the contacts till they open up enough so an arc won't form or revers current flow. There is a circuit which allows AC relays to be used at near AC ratings on DC. There is an electronic DC suppressor now which shorts the contacts for a time. Any FET does that when powered called the Miller Effect. They may use a version of this. A capacitor can also instantly look like a short and it is sized large enough across the contacts. It needs a few extra parts to prevent that stored energy from destroying contacts when they close again.

 

[hwy17]

See crude diagram :>

Breaking procedure 1 then 2 then lastly 3 where resistor is disconnected last.

You would still get an arc at 2. The resistor is a resistor so it would resist accepting enough of the current to make a difference. Like there would be a difference, but not a significant one. If the resistor was weak enough to take a lot of the current, then it would have it's own arc problem when it was disconnected.

 

[Scph9002]

this will definitely not help. No experiments are needed. This is well documented science. The bible of things which go arc in the night is GASEOUS CONDUCTORS by James Dillon Cobine. The handiest book I have. I actually have a couple books from his private library. You want something to either short the contacts till they open up enough so an arc won't form or revers current flow. There is a circuit which allows AC relays to be used at near AC ratings on DC. There is an electronic DC suppressor now which shorts the contacts for a time. Any FET does that when powered called the Miller Effect. They may use a version of this. A capacitor can also instantly look like a short and it is sized large enough across the contacts. It needs a few extra parts to prevent that stored energy from destroying contacts when they close again.

I tried it anyway...

And you where right, made you click the spoiler tho