Question

Question: Assume that a utility’s system consists of two feeders: feeder serving customers and feeder serving customers. Annual outage data during is given in Table 14.6 and 14.10 for these feeders. Calculate the SAIFI, SAIDI, CAIDI, and ASAI for the system, excluding the major event.

Short answer

Answer

The value of SAIFI, SAIDI, CAIDI and ASAI are ,, and respectively.

Step-by-step solution

Write the given data from the question.

From table 14.0

Outage duration (minutes)	Number of customers interrupted
14.4	342
151.2	950
89.5	125
654.6	15
32.7	2,200
10,053*	4,000
40	370

from table 14.6

Outage duration (minutes)	Number of customers interrupted
8.17	200
71.3	600
30.3	25
267.2	90
120	700
10	1500
40	100

Total number of customers served

4500+2000 = 6500

Determine the equations to calculate the SAIFI, SAIDI, CAIDI, and ASAI for the system, excluding the major event.

The equation to calculate the SAIFI (System Average Interruption Frequency Index) is given as follows.

$\mathit{S}\mathit{A}\mathit{I}\mathit{F}\mathit{I}\mathbf{=}\frac{\mathbf{\sum }\mathbf{T}\mathbf{o}\mathbf{t}\mathbf{a}\mathbf{l}\mathbf{}\mathbf{n}\mathbf{u}\mathbf{m}\mathbf{b}\mathbf{e}\mathbf{r}\mathbf{}\mathbf{o}\mathbf{f}\mathbf{}\mathbf{c}\mathbf{u}\mathbf{s}\mathbf{t}\mathbf{o}\mathbf{r}\mathbf{m}\mathbf{e}\mathbf{r}\mathbf{s}\mathbf{}\mathbf{i}\mathbf{n}\mathbf{t}\mathbf{e}\mathbf{r}\mathbf{r}\mathbf{u}\mathbf{p}\mathbf{t}\mathbf{e}\mathbf{d}}{\mathbf{T}\mathbf{o}\mathbf{t}\mathbf{a}\mathbf{l}\mathbf{}\mathbf{n}\mathbf{u}\mathbf{m}\mathbf{b}\mathbf{e}\mathbf{r}\mathbf{}\mathbf{o}\mathbf{f}\mathbf{}\mathbf{c}\mathbf{u}\mathbf{s}\mathbf{t}\mathbf{o}\mathbf{m}\mathbf{e}\mathbf{r}\mathbf{s}\mathbf{}\mathbf{s}\mathbf{e}\mathbf{r}\mathbf{v}\mathbf{e}\mathbf{d}}$ …… (1)

The equation to calculate the SAIDI (System Average Interruption Duration Index) is given as follows.

$SAIDI=\frac{\sum Custormersinterruptedduration}{Totalnumberofcustomersserved}$ …… (2)

The equation to calculate the CAIDI (Customer Average Interruption Duration Index) is given as follows.

$CAIDI=\frac{SAIDI}{SAIFI}$ …… (3)

The equation to calculate the ASAI (Average Service Availability Index) is given as follows.

$ASAI=\frac{\sum Custormerhoursserviceavailability}{Customerhoursservicedemands}$ …… (4)

 Step 3: Calculate the SAIFI, SAIDI, CAIDI, and ASAI for the system, excluding the major event.

Calculate the value of SAIFI.

$$\begin{gathered} \text{SAIFI}=\frac{\left[200+600+25+90+700+1500+100 \\ +342+950+125+15+2200+370 \\ \right]}{6500} \\ \text{SAIFI}=\frac{7217}{6500} \\ \text{SAIFI}=1.11 \end{gathered}$$

Hence the value of SAIFI is 1.11 .

Calculate the value of SAIDI.

$$\begin{gathered} \text{SAIDI}=\frac{\left[8.17\times 200+71.3\times 600+30.3\times 25+267.2\times 90 \\ +120\times 700+10\times 1500+40\times 100+14.4\times 342 \\ +151.2\times 950+89.8\times 125+654.6\times 15+32.7\times 2200 \\ +40\times 370\backslash \mathrm{hfill} \\ \right]}{4500} \\ \text{SAIDI}=\frac{428568.3}{6500} \\ \text{SAIDI}=65.934 \end{gathered}$$

The value of SAIDI is 65.934 minutes/ year and 1.0989 hours/year.

Calculate the value of CAIDI.

Substitute for SAIDI and for SAIFI into equation (3).

$$\begin{gathered} \text{CAIDI}=\frac{1.0989}{1.11} \\ \text{CAIDI}=0.99 \end{gathered}$$

Hence the value of CAIDI is 0.99 hours /year .

Calculate the value of ASAI.

$$\begin{gathered} \text{ASAI}=\frac{8760\times 4500-\frac{\left[8.17\times 200+71.3\times 600+30.3\times 25+267.2\times 90 \\ +120\times 700+10\times 1500+40\times 100+14.4\times 342 \\ +151.2\times 950+89.8\times 125+654.6\times 15+32.7\times 2200 \\ +40\times 370 \\ \right]}{60}}{8760\times 6500} \\ \text{ASAI}=\frac{56940000-\frac{428568.3}{60}}{56940000} \\ \text{ASAI}=\frac{56940000-7142.805}{56940000} \\ \text{ASAI}=0.9998 \end{gathered}$$

Hence, the value of ASAI is percentage is 99.98%.