Class 1E Distribution

Question 1

What do the following lights mean:
Red
Green
Bright Green
Clear
White

Answer 1

Red - breaker closed, continuity through the trip coil
Green- breaker open
Bright Green - 86 lockout relay or closed in Test
Clear - closing springs are charged
White - lockout relay has continuity and not tripped

Question 2

What is the time delay for Degraded Voltage (<90%) of a 4.160 class bus?

Answer 2

7 seconds with a SIAS
35 seconds without a SIAS

2-4 logic with undervoltage

Question 3

What is the time delay for Undervoltage (<75%) of a 4.160 class bus?

Answer 3

2 seconds

2-4 logic with degraded voltage

Question 4

List the SIAS load shed MCC’s

Answer 4

• NHN-M19 (L35) and NHN-M71 (L31) of Load Group A
• NHN-M72 (L34) and NHN-M20(L36) of Load Group B

Question 5

What is the interlock for the class 4.160 bus Normal Supply breakers, when closing from locally (from the swtichgear)?

Answer 5

1) If being closed from the switchgear, the other supply breakers (DG and ALT) must be open.

2) A lockout on any of the three supply breakers will prevent closing from either B01 or locally.

3) Generator Differential Lockout (86D) relay must be reset.

Question 6

What is the interlock for the class 4.160 bus Normal Supply breakers, when closing from B01?

Answer 6

1)If being closed from B01, it is required that the sync switch be turned on.

2) A lockout on any of the three supply breakers will prevent closing from either B01 or locally.

3) Generator Differential Lockout (86D) relay must be reset.

Question 7

How long are class batteries rated for?

Answer 7

2 hours

Question 8

What is the normal operating voltage of the class battery buses during a normal line up?

Answer 8

135 vdc