Distribution Line to Line Insulators

[johnnyball]

Does anyone know of a manufacturer that makes a 15kV class insulator to use
for the purpose of minimizing fault induced conductor gallop,due to magnetic forces and does the NESC allow insulators to be used for this purpose?

 

[jghrist]

See

http://www.macleanpower.com/products/item.asp?ITEM_ID=1498

 

[magoo2]

We have used some Salisbury spacers at 34.5 kV to control the conductors from slapping together from phase to phase faults. We generally don't like that solution because these insulators will track over time.

Before doing anything like this, have you looked at your recloser curves? If you can go with a faster trip characteristic, you may not need the spacers.

 

[johnnyball]

Thanks for the responses. We generally use a fuse-"sacrificing" approach with our protective schemes. For us, this seems to give better coordination by allowing more margin between protective devices, and has resulted in fewer nuisance trips, especially during storms. In other words, we opt for sub. breaker settings that give downline devices more time to operate or clear. We use instantaneous elements as well that are set fairly high, but we don't wish to set these any higher at the expense of more fault duty on our station equipment. Part of our problem is the fact that we normally operate with the secondaries of two fairly large power transformers tied together feeding a single bus, as opposed to a dual bus arrangement with a N.O. tie breaker. This mode of operation results in some significant fault levels near the station. We typically use phase & ground overcurrent seetings with inst. elements, but have contemplated going with maybe a negative sequence elementfor better sensitivity for line-line faults. Any ideas?