Electric Power Generation, Transmission, and Distribution

operation would not appear to be the result of loss of diversity but rather the high inrush currents. Since
inrush occurs during all energization and not just as a result of cold load pickup, it can be concluded
that cold load pickup is not a major factor in the application of FCIs.

Load Current

Fault

Current

Fault

Initiated

(Contacts

Closed)

2 s 2 s 2 s

Time

Reclosing Intervals

(Contacts Open)

"Fast" Operations

(Contacts Closed)

"Time Delay" Operations

(Contacts Closed)

Recloser

Lockout

(Contacts

Open)

Line Recloser

Dead Time

I sc Cycles^30 5 s 15 s 30 s

Current vs. Time

Feeder Breaker Reclosing

FIGURE 23.4 Reclosing sequences.

0

5

10

15

20

25

30

Transformers Laterals Feeders

Location

P.U. of Full Load

FIGURE 23.5 Magnitudes of inrush current.