# Pacific Gas & Electric (PCG)

## PCG»Topics» 4.3.1. Calculations of Annual Availability Performance Indices for Individual Voltage Classes

This excerpt taken from the PCG 10-K filed Feb 18, 2005.

4.3.1.    Calculations of Annual Availability Performance Indices for Individual Voltage Classes

Separate annual Availability performance indices shall be calculated for each Voltage Class and PTO as described below utilizing the Availability Measures discussed in Section 4.2.

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Annual Average Forced Outage(IMS) Frequency for All Transmission Line Circuits (Index 1):

 Fvc,k = 1Nk Nk S    fik i = 1

where

 Fvc,k = frequency index for the Voltage Class, vc, (units = Forced Outages(IMS) /Transmission Line Circuit). The frequency index equals the average (mean) number of Forced Outages(IMS) for all Transmission Line Circuits within a Voltage Class for the calendar year k. Nk = number of Transmission Line Circuits in Voltage Class in calendar year k. See Note 2, Section 4.2.1. fik = frequency of Forced Outages(IMS) for the ith Transmission Line Circuit as calculated in accordance with Section 4.2.1 for calendar year k.

Annual Average Accumulated Forced Outage(IMS) Duration for those Transmission Line Circuits with Forced Outages(IMS) (Index 2):

 Dvc,k = 1No,k No,k S    dik i = 1

where

 Dvc,k = duration index for the Voltage Class (units = minutes/Transmission Line Circuit). The duration index equals the average accumulated duration of Forced Outages(IMS) for all Transmission Line Circuits within a Voltage Class which experienced Forced Outages(IMS) during the calendar year k. No,k = number of Transmission Line Circuits in the Voltage Class for which the Forced Outage(IMS) frequency Availability Measure (fik) as calculated in accordance with Section 4.2.1 is greater than zero for the calendar year k. See Note 2, Section 4.2.1. dik = accumulated duration of Forced Outages(IMS) for the ith Transmission Line Circuit having a Forced Outage(IMS) frequency Availability Measure (fik) greater than zero for calendar year k as calculated in accordance with Section 4.2.1.

Annual Proportion of Transmission Line Circuits with No Forced Outages(IMS) (Index 3):

 Pvc,k = Nk - No,k Nk

where

 Pvc,k = index for the proportion of Transmission Line Circuits for the Voltage Class with no Forced Outages(IMS) for the calendar year k. Nk = number of Transmission Line Circuits in Voltage Class for calendar year k. See Note 2, Section 4.2.1. No,k = number of Transmission Line Circuits in the Voltage Class for which the Forced Outage(IMS) frequency Availability Measure (fik) as calculated in accordance with Section 4.2.1 is greater than zero for the calendar year k. See Note 2, Section 4.2.1.

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