Arteche smART P500, Instruction Manual

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7BRELIABILITY INDEXES
PROTECTION, CONTROL AND METERING FUNCTIONS
except that the denominator is the number of customers interrupted versus the total
number of utility customers. CAIDI is,
( )( )
( )
∑
∑
=
i
i i
C
T C
CAIDI
2.7.3. SYSTEM AVERAGE INTERRUPTION FREQUENCY INDEX
The System Average Interruption Frequency Index (SAIF I) is the average number of
times that a system customer experiences an outage during the year (or time period
under study). The SAIFI is found by divided the total number of customers interrupted
(Ci) by the total number of customers served (NTC). SAIFI, which is a dimensionless
number, is,
NTC
C
SAIFI
i
∑
=
2.7.4. CUSTOMER AVERAGE INTERRUPTION FREQUENCY
INDEX
Similar to SAIFI is CAIFI, which is the Customer Average Interruption Frequency Index
The CAIFI measures the average number of interruptions per customer interrupted per
year. It is simply the number of interruptions that occurred divided (Ci) by the number of
customers affected by the interruptions (NCA). The CAIFI is,
NCA
C
CAIFI
i
∑
=
2.7.5. MOMENTARY AVERAGE INTERRUPTION FREQUENCY
INDEX
The MAIF I is the Momentary Average Interruption Frequency Index and measures the
average number of momentary interruptions that a customer experiences during a given
time period. Most distribution systems only track momentary interruptions at the