thoughts around Breaker Maintenance switch (240kV)

[Sn00ze]

With the design of a single line (240kV) breaker for 6 feeders (34.5kV). I am curious what people's thoughts are around adding a breaker maintenance switch for the breaker's Line protections.

Unecessary? good idea? Old fashioned? inadequate?

-Sn0

 

[davidbeach]

Could you clarify what you're calling a maintenance switch? What you mean and what others might think of could be very different.

 

[crshears]

What davidbeach said; maybe I'm the one Sn00zing here, but I can't wrap my head around what you're asking...how do you use a single line breaker at 240 kV for six feeders @ 34.5 kV? Are you talking radial 230 kV circuit arrives at a transformer station? Or are you talking about performing relay maintenance on one of two duplicate dual-redundant relay schemes? Or are you asking after a selector switch on the breaker's control circuitry? Or about a 240 kV disconnect switch used to isolate the breaker from high-voltage sources?

Re-word, please.

CR

"As iron sharpens iron, so one person sharpens another." [Proverbs 27:17, NIV]

 

[Sn00ze]

Oh apologies. sometimes i get too myopic into my own thoughts. We have a number of feeders coming from turbines @ 34.5kV, this go into the switchgear (feeders) and then into a TX 24.5kV/240kV finally leaving through the 240kV line/ line breaker.


What i am referring to as a "maintenance switch" is no more than a module inside the control building that takes in the status of the breaker and then it gives a "maintenance" logical 1 or 0 to the line protection and breaker control in order to trip block as well as visual aid and lock out for crews working on the line during routine maintenance or during fault conditions. My opinion is that this is being done through the bus or TX lock out relays or even within the settings in most relays. I know some clients are moving away from using this separate module.

 

[jghrist]

Some feeder relays will have a "Hot Line Tag" button that is programmed to prevent closing the breaker while work is being done on the feeder. A separate toggle switch could be used to assert a relay input and you could have relay logic do the same thing.

 

[crshears]

Thanks for the clarification, Sn00ze. My utility doesn't do this at all, so I have no further advice either yay or nay...

CR

"As iron sharpens iron, so one person sharpens another." [Proverbs 27:17, NIV]

 

[bacon4life]

It is common to Block reclosing and/or change protection sensitivity during maintenance. Seems like it is also common to incorporate this feature into relay logic rather than using a discrete switch.

 

[Sn00ze]

First of all, thanks for the input guys.

jghrist: This is exactly what i've seen too. Which is why i think adding the redundant switch might be overkill.

crshears: no worries, I can see why. i think this switch is an old fashioned way of doing it in my province.

bacon4life: 100%