An infrared window is a data collection point for a thermal
imaging camera. Adoption of this technology is growing
fast as increased awareness of electrical safety and risk
reduction drives its acceptance. IR windows also enable
systems to be inspected under load so their true ‘health
status’ can be quickly ascertained, as Iriss explains

Suitable for every industry that uses
energy, IR windows save inspection
time while facilitating more efficient
and safer workplace practices. They
eliminate the need for cumbersome PPE by
negating the need to remove panel covers.

The result is a streamlined process which can
cut up to 90% of man hours spent on
traditional inspections while increasing the
quality of inspections and safety of personnel.

Various types of lens materials can be used
in IR windows but one that is proving
increasingly popular is industrial grade,
transmissive polymer. It is immune from the
mechanical stresses that can cause a fluoride
crystal lens to shatter. The material can also
be economically used to create an IR window
of any shape or size to suit the application,
allowing multiple components and busbars
to be inspected in a single camera scan.

London Stansted Airport
With the installation of IRISS CAP Series
polymer infrared windows at London
Stansted Airport, savings on thermographic
inspection time and associated costs have
been extensive. Payback was rapid, but the
benefit extends beyond that. If the airport
fails to meet an agreed level of service,
compensation becomes due – to customers,
airlines and handling agents. This new
method of inspection provides a critical
safeguard against this likelihood.

As the airport is open for business 24/7,
engineers only had 4h per night in which to
conduct predictive maintenance of low
voltage equipment. By the time they made
the system safe, the window of opportunity
reduced even more. This meant the entire
inspection cycle was significantly protracted
and no system could be checked under load.

Although efficient maintenance had so far
prevented serious low voltage system failures,
engineering compliance manager, David
Potter, wanted greater assurance. He had
considered infrared windows to complement
outsourced thermal imaging surveys but
crystal versions were considered unsuitable
given the size of the equipment that needed
to be monitored.

The ‘Eureka’ moment came when David
Potter read about IRISS’ Custom Application
Product (CAP) Series infrared windows
made from transmissive polymer. This fully
impact resistant material allows the window
to be any size which is useful for applications
involving large switchgear.

Potter explains: “It’s rare to see something
completely new that works well. The
specification was approved on 6th November
2012, a comprehensive installation plan was
then drawn up by IRISS and the entire job
was completed by Christmas.”
IRISS worked flexibly to complete the job
within the time constraints imposed by the
24h operation. In total 72 windows were
installed, comprising a combination of 6, 12
and 24in products – all available in the
standard range. The largest window is of
course suitable for the thermal inspection of
busbars and multiple components.

Time savings
Following the installation of the CAP Series
windows, the impact on inspection time was
immediate. IRISS undertook the first
thermal imaging survey with the benefit of
its infrared windows in January this year.

It took just 5h to complete the job in
daylight hours. Previously it would take
engineers two nights to inspect one panel.

There was no need for isolations or back feed
and personnel safety is assured. A single
thermographer without full PPE can do
everything.

“I now have a print out of each system’s
thermal performance and, for the first time,
a benchmark on which to base future thermal
inspections,” adds Potter. “Previously, it would
have taken us a couple of years to inspect the
complete network and even then we had no
idea of what was happening under load.

“Now we can see the live circuits and
cables and the temperature rise on busbars.

This means we are able to apply trends to
every system. I now know the airport
terminal is truly safe and that’s a big tick
against my list. I’m really sold on this
technology.