Ieee std 1366-2012 (Revision of ieee std 1366-2003) ieee guide for Electric Power Distribution Reliability Indices

Table 7 —Example for a feeder serving 1 000 customers with a sustained interruption 
Time from 
initial fault 
(min) 
Description Customers 
remaining 
interrupted 
Customers 
restored 
— 
The initial fault occurs, the feeder breaker opens, and all 1 000 
customers are interrupted. Switches are opened along the feeder. 
1 000 
— 
45 
The feeder breaker is closed, but only 500 customers are restored. 
500 
500 
60 
Through closing a switch, an additional 300 customers are restored. 
200 
800 
70 
An additional incident occurs which causes the feeder breaker to 
open, interrupting the 800 customers previously restored. 
1 000 
— 
90 
The feeder breaker is closed, and restores 800 customers. 
200 
800 
120 
Permanent repairs are completed and the remaining 200 customers 
are restored. The outage event is concluded. 
— 1 
000 
Totals 
N/A 1 
800 
Figure 2 illustrates the example described in Table 7. Note that both the block of 500 customers and the 
block of 300 customers experience two interruptions during this event. 
Figure 2 —Step restoration time chart 
Table 8 enumerates the CI and CMI for the example. 
Table 8 —Restoration steps for the example 
Time Interruption 
duration 
(min) 
CI CMI 
00:00-00:45 45 
500 22 
500 
00:00-01:00 60 
300 18 
000 
01:10-01:30 20 
800 16 
000 
00:00-02:00 120 
200 24 
000 
Total 
1 800 
80 500 
Example SAIFI = 1 800/1 000 = 1.8 interruptions
Example CAIDI = 80 500/1 800 = 44.7 min
Example SAIDI = 80 500/1 000 = 80.5 min 
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IEEE Std 1366-2012 
IEEE Guide for Electric Power Distribution Reliability Indices 
Copyright © 2012 IEEE. All rights reserved. 
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