2016
Insulator and Hardware Maintenance
What is an insulator?
Insulators
are
the
glass,
composite or ceramic-looking
discs that connect the conductor
(wire) of a transmission line with
the supporting tower or pole.
They insulate the line so that the
electricity being
transported
stays on the line and does not
become earthed through the
supporting structure.
Why do they need to be
maintained?
Over the life time of a
transmission line, the insulator
and other attachments on the
line (like dampers and armour
rods) can corrode or get
damaged sufficiently to require
replacement or repair.
What sort of equipment and
crew is needed to undertake
insulator and hardware
maintenance?
It depends on the work required.
For simple insulator
replacements, the work crew may
number between four to six
people on site, with one or two
light four wheel drive type
vehicles, trailers and a capstan
winch.
For more complex replacements – for example spacer replacements on duplex (two wire)
or triplex (three wire) conductor configurations – the work may require the use of a
helicopter to deploy line trolleys and people onto the line. In any event, our notification to
landowners will cover the exact nature of the work required.
What about the impact of the work on properties?
Where possible, we work with landowners to minimise disruption during this work and this
includes agreeing access and timing of work on the property. The activity will be confined
to the area around the transmission towers or poles and access routes. The affected area
2
(about 1000 m directly around the structure) will be cordoned off during the work. Impact
on crops and pasture would be kept to a minimum.
How is the work undertaken?
April2016
The first step is to isolate or de-energise the line to allow the work to take place safely. The
works area around the tower is then cordoned off. If the work is carried out with the line deenergised, line technicians will climb the tower and install earth leads from the conductors
to the tower. Rigging to allow access and work to take place is then installed. The old
insulators and associated hardware are disconnected and lowered to the ground using a
winch, and the new insulators and hardware are then capstan winched into position.
If the work is carried out ‘live line’ the replacement techniques are similar to those above (but without the
earth leads). In this case landowners may observe minor arcing around the insulator connections which
is normal.
How long does insulator and hardware maintenance take?
It depends on the work required. For simple insulator replacements, work crews typically complete this
work within a day, however they may seek to undertake other tower rehabilitation work at the same time
(eg replacing corroded steel within a tower, or replacing tower signage) which might extend the work
over two days.
For more complex insulator and hardware replacements – for example spacer replacements on duplex
or triplex conductor configurations – the work may take up to four days.
Our notification to landowners will include details on the work and timings for completion.
Will the insulators look the same as before?
The new installed insulators may look different depending on what type of material is used. There are
three different types of insulator material: porcelain, glass or composite with the choice dependent on
location. Examples of each are shown in the photographs below:
For more information, call Transpower on 0508 526 369 (0508 LANDOWNER)