Puhoi Area October 2014 Background The Puhoi region is supplied by - - PowerPoint PPT Presentation

Vector Network Reliability

Puhoi Area

October 2014

Background

• The Puhoi region is supplied by two HV

feeders; the Waiwera feeder which

• riginates from Orewa (brown) and the

Satelite which comes from Warkworth (red).

• Each feeder exceeds 100km in length and

is predominantly overhead.

• Both feeders are classified as rural, in total

they supply 2,021 connections.

Puhoi Village

• The two feeders meet at the Puhoi Village, the

Southern end is supplied by the Satellite feeder and the Northern end receives power from Waiwera.

• There is an 'open point' between the feeders, this

can be closed to allow power to be back-fed when required.

• Each side experiences different outages.

Service Levels

• The level of service we are able to provide

depends on where you live.

• Urban homes have fewer faults on average

and are shorter in duration than rural feeders

• This is due to the length and exposure of

rural overhead lines and a number of factors that are largely outside our control such as:

• Severe weather conditions
• Bird strikes
• Car vs pole accidents
• Vegetation

Unplanned Outage Causes

Note: 38% of faults on the Northern end and 57% of faults on the Southern end occurred during storm periods.

Unplanned Outage Durations

Distribution of Outages - Count

• This plot shows the distribution and count of

fault outages over the last two years.

• Puhoi is near the end of both feeders so

unfortunately experiences relatively poor reliability.

• Outage counts over the last 12 months have

been high, largely due to the four major storms earlier this year;

• 14-17 March
• 17-20 April
• 10-16 June
• 8-12 July

Distribution of Outages - Duration

• This plot shows the cumulate duration of all

fault outages over the last two years. Values are in hours.

Preventative Maintenance

• Vector has a comprehensive preventive maintenance

program with standards regarding;

• Inspection Tasks.
• Test Activities.
• Maintenance Servicing.
• Condemned Pole Assessment.
• Feeder maintenance and replacement tasks are driven

by asset condition and risk.

• There have been 6 HV outages caused by conductor failure on the

spur line to Wenderholm Regional Park from 2011 to 2014. We have recently completed a conductor replacement exercise removing the problematic 16mm Cu conductor.

• In addition, Wenderholm is locked after-hours with no vehicle

access to patrol/repair the line. Over the coming months we plan to install additional DDOs (fuses) before the line enters the park, splitting the protection on this spur line and improving restoration times.

• New inspection technologies are constantly being
• assessed. New-generation ultrasonic pole surveys were

introduced in 2013.

Tree Trimming

• At least 1/3 (& up to 3/4) of all faults* are vegetation-related.
• Vector has a Regulatory obligation to maintain safety clearance distances around electricity lines.

Tree owners have regulatory obligations to trim their trees in accordance with these safety clearances

• As part of our historical tree inspection cycle, Vector last undertook network inspections, issued CTNs

and then trimming in:

• 38SATE: 2006/2011/underway
• 26WAIW: 2009/2013/underway
• Our 2014 feeder tree survey’s identified two sets of works:
• Trees currently breaching Regulatory clearance distances from electricity lines

− Tree owners (private or Council) will be issued with regulatory Cut Trim Notices to restore clearances (at their cost)

• 38SATE: Private: 24 sites = 145 trees

& Council: 7 sites = 63 trees

• 26WAIW: Private 17 sites = 159 trees

& Council: 5 sites = 15 trees

− Where these are ‘first cuts’ Vector will be undertake the works for the tree owner (at our cost)

• 38SATE: 14 sites
• 26WAIW: 6 sites
• Trees that pose a risk to the network (outside of regulatory safety clearance distances)

− Identified trees that have a high-risk of causing a fault due to: flying debris/broken branches, tree fall hazard − We will be liaising with each private tree owner to agree trimming or removal requirements, and Vector will contribute to the cost depending on what is agreed.

• 38SATE: Private: 5 sites = 67 trees
• 26WAIW: Private: 25 sites = 155 trees
• Tree owners will start receiving letters soon, and we request they contact the Treescape liaison person detailed on the

letter to work through the detail of the tree trimming works required.

* 33% of faults were verified as vegetation issues. In addition 40% of faults were ‘transient’ - a high proportion of them will be vegetation related.

Protection Scheme Review

• Protection systems do not prevent feeder

faults, but do minimise their impact.

• Both feeders supplying Puhoi have

sophisticated, multi-tiered systems including automated devices and numerous HV switches and fuses.

• The feeders are being reviewed to further

refine the system and leverage technological developments.

• Additional fuses, sectionalising fuses and

isolation points will be installed at optimal locations.

Electrical Safety

General

• Report any hazards to 0508 VECTOR (0508 832 867).
• Broken lines - Treat all power lines as live at all times and keep everyone well clear
• f the area.
• Arcing/sparking Equipment – Keep clear, report immediately.
• Car vs Pole - If lines are down stay in the car until help arrives. If forced to

evacuate, jump clear. Do not to touch the vehicle and the ground at the same time. Working Safely

• Minimum safe work distances;
• >4m from OH lines
• >5m from a pole when digging

A close approach consent is required to work closer.

• High Loads - You must apply for a high load permit if you plan to move any tall

structure such as a house or a boat.

• If you are unsure about anything before you start any work near our networks call

0508 VECTOR (0508 832 867) or visit www.vector.co.nz and download ‘A guide for working safely’.

Questions?