1 Table of contents 310

AMP 2019-2029

Electricity Asset Management Plan 2019-2029

42

Vector Limited://

two causing minor mechanical abrasion. Contributing to the increase in RY18 is the improved reporting of incidents mentioned in Section 2.3.1.

TARGET Zero. With safety always being Vector’s highest priority, we strive to achieve no asset safety related incidents causing harm to employees, contractors, and the public. 2.4 RELIABILITY This considers the ability of the network to deliver electricity consistently when demanded under normal design conditions. We are committed to meeting the Regulatory quality metrics. DEFINITION SAIFI measures the average number of outages per customer per RY, the value expressed in number of interruptions. This is one of the key metrics used to assess the reliability of the network. It is calculated as the total number of customer interruptions divided by the total number of customers served, where interruptions are for a period of 1 minute or longer. MEASUREMENT 𝑆𝑆𝑆𝑆𝑆𝑆𝑆𝑆𝑆𝑆 = (𝑑𝑑𝑑𝑑𝑑𝑑𝑑𝑑𝑑𝑑 𝑛𝑛𝑛𝑛𝑛𝑛𝑛𝑛𝑛𝑛𝑛𝑛 π‘œπ‘œπ‘œπ‘œ π‘–π‘–π‘–π‘–π‘–π‘–π‘–π‘–π‘–π‘–π‘–π‘–π‘–π‘–π‘–π‘–π‘–π‘–π‘–π‘–π‘œπ‘œπ‘œπ‘œπ‘œπ‘œ) / (π‘Žπ‘Žπ‘Žπ‘Žπ‘Žπ‘Žπ‘Žπ‘Žπ‘Žπ‘Žπ‘Žπ‘Žπ‘Žπ‘Ž 𝑛𝑛𝑛𝑛𝑛𝑛𝑛𝑛𝑛𝑛𝑛𝑛 π‘œπ‘œπ‘œπ‘œ 𝑐𝑐𝑐𝑐𝑐𝑐𝑐𝑐𝑐𝑐𝑐𝑐𝑐𝑐𝑐𝑐𝑐𝑐) SAIFI only measures outages caused by an event on the HV network and does not include the LV network. The SAIFI dataset is normalised using a process defined by the Commerce Commission in the DPP. This process reduces planned interruptions by 50% as it is considered that customers are less impacted by interruptions that are planned. It also limits unplanned SAIFI on days where a major event has occurred (e.g. storms), to prevent these extreme events distorting the overall SAIFI data. The following formula is used: 2.4.1 SYSTEM AVERAGE INTERRUPTION FREQUENCY INDEX (SAIFI) SERVICE LEVEL

𝑆𝑆𝑆𝑆𝑆𝑆𝑆𝑆𝑆𝑆 γ€—

_𝑁𝑁𝑁𝑁𝑁𝑁𝑁𝑁𝑁𝑁𝑁𝑁𝑁𝑁𝑁𝑁𝑁𝑁𝑁𝑁 = (0.5 π‘₯π‘₯ γ€–

𝑆𝑆𝑆𝑆𝑆𝑆𝑆𝑆𝑆𝑆 γ€—

_𝑝𝑝𝑝𝑝𝑝𝑝𝑝𝑝𝑝𝑝𝑝𝑝𝑝𝑝 ) + γ€–

𝑆𝑆𝑆𝑆𝑆𝑆𝑆𝑆𝑆𝑆 γ€—

_𝑒𝑒𝑒𝑒𝑒𝑒𝑒𝑒𝑒𝑒𝑒𝑒𝑒𝑒𝑒𝑒𝑒𝑒

γ€–

Where:

γ€– SAIFI γ€— _planned is the sum of daily planned SAIFI values in the assessment period; and

γ€– SAIDI γ€— _unplanned is the sum of daily unplanned SAIFI values in the assessment period, where if any daily value of unplanned SAIFI is greater than the SAIFI Unplanned Boundary Value then the daily value equals the SAIFI Unplanned Boundary Value.

The SAIFI Unplanned Boundary Value is calculated in accordance with the Commerce Commission process. This limit is set to 0.039 for the current regulatory period (1 April 2015 to 31 March 2020).

All of Vector’s interruption data is held in our HV Spec database which is used to calculate and report on SAIFI performance. SAIFI is measured on a monthly and annual basis to inform asset management practises. For regulation purposes, SAIFI is reported to the Commerce Commission on an annual basis. SAIFI reporting to the Commerce Commission is subject to an external audit. The SAIFI target is set by the Commerce Commission’s regulatory determination every 5 years. It is largely based on the average SAIFI performance over a 10-year historical Reference Period. The process for setting this target is specified in the DPP.

DESCRIPTION

RY15

RY16

RY17

RY18

SAIFI

1.41

1.11

1.85

2.14

Table 2-7 SAIFI

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