Currently designing a 220 kV SS, some designs implement gantry beam underhung insulator (I or sometimes V insulators) to support dropper from line side insulator string down to surge arrestor or disconnector.
The image below shows I string used for droppers as well as gantry jumpers.
![URL]](https://res.cloudinary.com/engtips/image/fetch/w_800,c_lfill,q_auto,f_auto,g_faces:center/[URL unfurl="true"]http://www.celiklerdemirdirek.com.tr/siteimages/2013_06/2013_06_19/photo_22_3.jpg[/URL])
I understand that for jumpers it is to avoid conductors encroaching clearances, however, for the dropper (The bay on right above), the dropper can go directly to the equipment below (mostly a voltage transformer).
what is the criterion for underhung string? is it to avoid clearances encroachment during wind blows? to slightly reduce the short circuit tensile forces on the equipment terminals below ( I don't see any major force reduction with U/H string)?
any clues?
The image below shows I string used for droppers as well as gantry jumpers.
I understand that for jumpers it is to avoid conductors encroaching clearances, however, for the dropper (The bay on right above), the dropper can go directly to the equipment below (mostly a voltage transformer).
what is the criterion for underhung string? is it to avoid clearances encroachment during wind blows? to slightly reduce the short circuit tensile forces on the equipment terminals below ( I don't see any major force reduction with U/H string)?
any clues?
