115 kV Line Tap - Disconnect Sw Requirements
115 kV Line Tap - Disconnect Sw Requirements
(OP)
We've been involved with several cogeneration projects that involved interconnection to a nearby 115 kV transmission line. In addition to the circuit switcher and disconnect switch at the substation at the cogen site, a second disconnect switch is always provided at the actual line tap, which could be some distance from the site.
Utilities sometimes install two additional disconnects on each side of the line at the tap point - three disconnects at the tap point.
I'm interested in some feedback from some of the utility engineers regarding the need for the two disconnect switches in the line - do you require these, and if so, what are the arguments for the necessity of these two additional switches?
Thanks,
Dave
Utilities sometimes install two additional disconnects on each side of the line at the tap point - three disconnects at the tap point.
I'm interested in some feedback from some of the utility engineers regarding the need for the two disconnect switches in the line - do you require these, and if so, what are the arguments for the necessity of these two additional switches?
Thanks,
Dave






RE: 115 kV Line Tap - Disconnect Sw Requirements
I experienced once a time with a pure load supplying line tap (50km) on a 1xxkV transmission line. We did not pay attention to the tap configuration at the very beginning since it is a small part of the whole project- cost aspect.
Later on, when the time came, people asked me to tell how many disconnect switches( vacuum interrupters)on the tap point are required.
The major concern I can recall was related to real time operation. How to isolate the fault after line tripped (Main 1XX transmission line and tap line)and operate the rest of the system. Finally, after considering all possible system scenarios together with the CB configurations on other ends, we decided to only install two disconnect switches at TAP position.
I would believe how many disconnect switchs at TAP point will be depend on case by case - your system configuration, operating orders and the way to operate the system.
How many VI will depends on teh EMTP people to tell drop the light loaded capacitive line concerns.
RE: 115 kV Line Tap - Disconnect Sw Requirements
RE: 115 kV Line Tap - Disconnect Sw Requirements
RE: 115 kV Line Tap - Disconnect Sw Requirements
RE: 115 kV Line Tap - Disconnect Sw Requirements
In this particular case,one side of the 115 kV line runs a couple of miles to a small distribution sub and stops so they could never feed power that way if the other side of the 115 kv line was open.
RE: 115 kV Line Tap - Disconnect Sw Requirements
More generally, it would depend on how easy it would be to schedule maintenance outages with the IPP.