Lockout points MV CBs

[buffalonymann]

It appears the only way to lockout medium voltage circuit breakers is to rack them out and offline of the buss. I have 4160 VAC VR 1200 amp breakers by square D

 

[JoeStillman]

Is there a reason you wouldn't want to rack it out?

 

[zog]

It appears the only way to lockout medium voltage circuit breakers is to rack them out and offline of the buss. I have 4160 VAC VR 1200 amp breakers by square D

Correct, it's the only safe way to do it. Keep in mind the gap in a VI is about 1/8" when the breaker is open, you want your life depending on a 1/8" gap. What if the VI loses vacuum? Do you know what the vacuum level is in your VI's? Not many plants take the time to test that and have no idea what the remaining life is.

 

[Jraef]

Correct, it's the only safe way to do it. Keep in mind the gap in a VI is about 1/8" when the breaker is open, you want your life depending on a 1/8" gap. What if the VI loses vacuum? Do you know what the vacuum level is in your VI's? Not many plants take the time to test that and have no idea what the remaining life is.

Not only that, but if the vacuum bottle DOES have to interrupt a fault, the contacts can burn and despisit conductive material all over the inside of the bottle. At MV it doesn’t need to conduct very much to be lethal.

 

[Tony S]

After having a VI fail I wouldn’t even entertain the thought of relying on the breaker alone for isolation.

We did have one guy who was terrified of applying locks to the isolation shutters, I wonder if our OP has a similar problem?

 

[Jraef]

I had a municipality I work with tell me they are not allowed to rack out breakers as a circuit disconnect because they determined that the process of racking them out was too dangerous. So they have been adding redundant isolation switches to everything. I showed them the remote racking mechanism that Zog’s sister company makes, they had never seen anything like it. A year later though and their safety committee is still “evaluating the concept”...

 

[zbang]

A year later though and their safety committee is still “evaluating the concept”...

Translated as "We didn't think of that."

 

[topgone]

Translated as "We didn't think of that."

Nope. The correct thing is "we don't know that!":happyno::happyno::happyno: