Failure Cause and Effect
The risk of blackouts and brownouts are
increasing on the power distribution grid due to aging infrastructure,
and a lack of automation systems that monitor the condition of critical
equipment at substations and elsewhere on the grid.
For example, transformer fluid leaks or
internal insulation breakdown cause overheating that leads to failures,
but many utilities don’t have automated thermal detection systems that
reveal these problems.
Whatever the cause, a critical substation
failure may cascade into series of failures. The result can be a massive
failure of banking facilities, security systems, manufacturing plants,
food refrigeration, communication networks, and traffic control systems.
Of course, an electric utility involved can lose huge amounts of
revenue and incur enormous costs in getting their systems up and running
High voltage electrical installations tend to heat up before they fail. By monitoring HV-equipment continuously with thermal imaging cameras costly breakdowns can be avoided.
Thermal imaging cameras help to save money
Thermal imaging technology can improve the
reliability and security of electric substations. Although electric
utilities have for many years used handheld thermal imaging cameras to
monitor substation equipment, quite some are now turning to permanently
installed thermal imaging camera systems. Through the use of automated
thermal imaging cameras and innovative software, FLIR and its partners
have developed monitoring systems that provide early warning of
impending equipment failures.
These systems employ advanced sensing and
measurement technology, control methods, and digital communications.
They are able to anticipate, detect, and respond rapidly to problems,
thereby reducing maintenance costs, the chance of failure, a blackout,
and lost productivity.
Just one example: one large utility discovered a
hot bushing rod in a substation transformer and repaired it at a cost
of only €12,000. A similar problem that occurred before the firm
instituted its thermal imaging program resulted in a catastrophic
failure that cost more than €2,250,000.
A few substation components whose thermal signatures are precursors to failure include:
- Power transformers (oil levels and pump operation)
Load tap changers (oil levels, other internal problems)
- Insulator bushings (oil levels and bad connections)
- Standoff insulators (moisture, contamination, degradation)
- Lightning arrestors (degradation of metal oxide disks)
- Circuit breakers (oil or SF6 leakage)
- Mechanical disconnects (bad connections, contamination)
- Control cabinets (wear and tear on fans, pumps, and other components)
Detection of temperature increases in these
components with thermal imaging cameras allows preventive maintenance
operations before an unplanned outage occurs due to outright failure.
Schematic overview of substation monitoring system
Principles of thermal imaging
The first principle of thermal imaging is “many components heat up before they fail”.
Second, all objects emit thermal radiation in the infrared spectrum that is not seen by the human eye.
Third, thermal imaging cameras convert that
radiation to crisp images from which temperatures can be read. This
non-contact temperature data can be displayed on a monitor in real time,
and can also be sent to a digital storage device for analysis.
Thermal imaging cameras do not require light to
produce images, and can see hot spots well before excessive heat or
loss of insulation leads to failure. They can be mounted in all-weather
housings and placed on pan/tilt drive mechanisms to survey large areas
of a substation. Due to FLIR's wide selection of lenses with different
focal lengths. Therefore, they support 24/7 monitoring in all types of
weather and locations.
FLIR thermal imaging cameras recognize
differences in the heat signatures of electrical components and the
surrounding background (such as the sky or clouds), and can compare the
temperatures of similar components in close proximity to one another.
Built-in logic, memory, and data communications allow them to compare
the temperatures in their images with user-defined settings, and send
that data to a central monitoring station for trend analysis, triggering
alarms, and generating exception reports. They can even notify facility
managers in remote offices of abnormal conditions by triggering an
email message. This makes them ideal for unattended monitoring of
Typical System Configurations
In co-operation with automation system
suppliers FLIR Systems works to create customized thermal imaging and
non-contact temperature measurement systems for electric substations.
These systems can automatically perform site
patrols, monitor equipment temperatures without human supervision. The
video images and their temperature data are carried over Ethernet,
wireless, or over fiberoptic cables to an appropriate interface that
communicates this data to the central monitoring location.
The diagram on this page depicts a typical
substation monitoring system that uses FLIR A310 thermal imaging
cameras. Systems of this type have been installed at substations
worldwide. The most advanced versions of these systems provide
time-stamped 3-D thermal modeling of critical equipment and areas.