Non-class 4.16kv (NB)

Question 1

What is the main purpose of the 4.6kv NB system ?

Answer 1

Provide power to 2 non-class Load Groups; 2 class Load Groups

Question 2

What’re the main equipment for 4.16kv (NB) ?

Answer 2

Two normal transformers(NBN-X01&NBN-X02);
4.16kv switchgear(NBN-S01&NBN-S02);
Two engineered safety transformers(NBN-X03&NBN-X04)

Question 3

What’re the cooling methods for normal service transformer ?

Answer 3

Phase 1:Natural Circ. Oil & air
Phase2: Natural Circ Oil & Forced Air (all fans turn on at 70degrees)

Question 4

What does control cabinet consist on normal service transformer ?

Answer 4

Normal and alternate power supply from non class 480MCC (NH); Will “auto-throwover”when normal power is lost

Question 5

When are breakers able to be closed on 4.16kv breakers ?

Answer 5

On a dead bus conditions verified by breaker interlocks

Question 6

Why is there a Fast Bus Transfer & when is it supposed to happen between NBN-S01&NBNS02?

Answer 6

Allows bus load to remain energized on a NBN-X01 or NBN-X02 fault;
.Differential and high side winding ground
.Sudden pressure surge
.High side winding overload and low side winding neutral ground overcurrent

Question 7

Cooling method for ESF transformer NBN-X03 & NBN-X04?

Answer 7

Phase 1: Natural oil Circ. & Ambient Air cooling
Phase 2:Natural Oil Circ. & Force Air