pole mounted transformers

[dinkelja]

How is the primary connected to on a pole mounted transformer. Like a small 75kVA, with 240/120 secondary. I only ever see one squiggly line down to a high voltage bushing going in to case, which is also tapped to an arrestor, grounded to the case. The secondary has its three insulated terminals protruding, and with the center (neutral) tap attached to the can through a ground strap. Then the case is grounded, through a wire run down the pole. I never understand the seeming simple circuit; where the second wire on the primary is connected?

 

[stevenal]

Internally connected to the can which is externally bonded to the neutral and the pole ground.

 

[cuky2000]

See the enclose link

http://cuky2000.250free.com/SA.jpg?view_image=1

This type of transformer has reduced insulation level connected phase to ground with only one HV bushing with common ground on the secondary and primary as shown in the figure in the link.

Beware that there are available single phase fully insulator pole mounted transformer with two bushings and isolated neutral grounded.