electrical surveys
and PAT
testing
ELECTRICAL CONDITION MONITORING & PREVENTIVE MAINTENANCE
A thermal imager provides a visualisation of heat, often invisible to the naked eye, which provides a quantitative analysis of temperature rise. A thermal imager can display and record temperature differences as low as 0.3°C which is far above the sensitivity required to detect electrical faults. A warm wire in a bundle of wires or amongst
hundreds of terminals will be immediately detected and displayed. Overheated components or components that are breaking down and
visually normal to an electrician will also be immediately apparent to a thermal imager operator.
Preventative maintenance surveys can save
on-line breakdowns, delivery schedules and in
the long term significant costs.
Infrared thermography or thermal imaging is a
recognised technique for detecting loose or
corroded connections. A poor electrical
connection under load will rise in temperature.
Arcing may occur and eventually the connection
will fail, or at worst, cause a fire resulting
in an expensive shut-down of the associated
equipment or machinery. The images below are
samples of overheated cables and poor
connections.
Temperatures, scales and associated information is
normally annotated on all images in our reports
and accompanied by a photograph or visible image
of each component. Temperature rise and thermal
spread is usually associated with specific
faults and our engineers will assess the
situation on site and prioritise for remedial
action.
In this image, the lower connection of the
right fuse had become loose creating a high
resistance.
Poor connections, load imbalances and
overloads are some reasons for a temperature
rise. Harmonics, often generated by switching
computer supplies can cause hot neutrals.
This image shows an overheated (55°C)
connector to a CT in a power station.
Ultrasound detection can be used to search
and locate corona discharges and arcing. Corona,
can if significant, increase the power factor.
This phenomenon is often caused by open buss
bars emitting RF noise where components have
sharp edges.
This image below shows an overheated
breaker.
For industrial electrical systems we use
a range of hand-held thermal imagers that provide
temperature measurements and other environmental
data. Our equipment is regularly calibrated and
emit no signals that will effect computers or
other sensitive equipment.
Our engineers have worked in the electrical
and electronics industry for many years and have
in-depth knowledge of electrical distribution
systems as well as thermography. All components are thermally scanned under load,
photographed and physically inspected to compile
detailed information for a hard copy report. The
infrared imagery is monitored live during the
survey and serious faults are immediately
reported to the site electrician. The entire
survey is also provided on CD for computer
viewing, analysis and archiving.
We have fixed rates throughout mainland
England and provide industry standard reports,
usually within two working days.
HIGH VOLTAGE POWER STATIONS
High voltage power stations and sub-stations are regularly surveyed to closely inspect insulators, transformers, capacitors and all mechanical connectors that are all exposed to the environment.
This survey work requires special knowledge of the operational systems as well as the thermography. Working with high voltages can be extremely dangerous and our thermography engineers have necessarily been required to pass National Grid Co competency examinations to work unaccompanied on site.
Hot connector 51°C
HIGH VOLTAGE POWER LINE SURVEYS FROM HELICOPTER
Overhead power lines can be rapidly filmed with
infrared from a helicopter. Hot connectors can
be instantly detected whilst flying at 40 mph or
more. Horton Levi has specialised thermal
imaging equipment (lower picture) fitted with instant
switch optics. The optics allow a wide view for economical and safe distance flying for fault searching and a narrow view for high detail of a detected faulty component.
The system has been used by major UK companies and is available for rent with
our engineer or we will provide training for our
clients to operate the system. Technical training and support is offered for field survey work, GPS positioning and post processing of the data.
Side looking Airborne Thermal Imager easily
deployed in most rotary wing aircraft.
More mechanically sophisticated FLIR system
which incorporates IR and visible in side
mounted pod.
Hot connectors 400,000 Volt line
Close visible view of connectors
HORTON LEVI LTD
TEL: (044) 1263-722522
For more information on this subject, to learn more about the company or to enquire about a quote, please visit our
corporate website at www.hortonlevi.co.uk
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