another utility distribution question - location of auto tap changer

[electrofelon]

This seems odd. Wouldn't you put an auto bank with tap changer downstream a ways after you built up some load and loss? Why put one right at the sub?

 

[Ingenieur]

on long lines with heavy concentrated loads they do install remotely

the primary purpose of station mntd is load regulation, diurnal, weekends, etc

 

[electrofelon]

I just dont recall seeing them at the substation. BTW, my OP was worded poorly "....downstream a way after you built up some load" obviously the most load occurs at the beginning of the circuit.....y'all knew what I meant.

 

[Ingenieur]

most of the time the loads are radial
you would need one on each branch
but one can serve all at the sub

each line is sized adequately for vdrop
but when all are loaded you get drop out of the xfmr
and rise when unloaded
more designed to compensate for xfmr drop

 

[topgone]

I just dont recall seeing them at the substation. BTW, my OP was worded poorly "....downstream a way after you built up some load" obviously the most load occurs at the beginning of the circuit.....y'all knew what I meant.

My experience is to install capacitors at end of lines for voltage improvement--> big loads at the end of lines! Tap-changer is built in the substation transformer.

 

[electrofelon]

Bonus: I was able to get a pic of the tap position. Wish I could read that label, not quite the right angle.

 

[electrofelon]

most of the time the loads are radial
you would need one on each branch
but one can serve all at the sub

each line is sized adequately for vdrop
but when all are loaded you get drop out of the xfmr
and rise when unloaded
more designed to compensate for xfmr drop

Makes sense to compensate for sag off the sub transformer. I guess the sub tranny doesnt have a tap changer built in?

Here is an example of more what I am used to. This is the line that serves my house. From substation goes about 5 miles on 7.62/13.2 then is dropped down to 4800 to feed the older lines. From there, its about 4 miles to my house. There is an auto tap changer about halfway on the 4800 line. That makes sense to me. Even have a picture of that one - nothing too exiting but Ill post it.