Power lFailures : causes and solutions

Power loss incidents, which amount in USA to $80 billion annually, cause tremendous
damages to computers and data, in industry, communication and data centers. Power failures
are markedly related to season, occurring mainly due to transformer failures, standby generator
starting troubles and underground cable malfunctions, all victims of poor maintenance that
could be avoided.

Forty two major worldwide Power Failure reported incidents were analyzed by UPSonNet. All
occurred during February 2009, each affecting thousands up to hundreds of thousands people.
The study results indicate that most failures are due to defective equipment that failed in Stormy
Weather. Proper preventive maintenance could have eliminated most defects and the associated
power failures.

Normally, during the dry period, contamination which includes electrically conductive materials
is collected on power line insulators. Rains and storms close the electric path causing shorts
and arcs, tripping line breakers. Sometimes utility poles catch fire due to the electric arcs.

Salt is used in some areas as part of winter road treatment, increasing the amount of
contamination spread by road vehicles kicking up salt from the roadway. This creates more
potential for electric arcs near freeways and major roads.

Trees are also a leading cause of power failures in winter. Winds and snow cause trees to fall.
The falling trees cut power lines. Some power lines create electric shorts and arcs between
adjacent power lines or from power lines to ground.

Lack of rain may affect power supply in places where considerable amount of power is
generated by hydropower. Kathmandu is now seeing severe power cuts, with no rain in the past
few months and decreasing water level in rivers feeding the hydropower plants.

Excessive heat, as experienced in Australia in February, overloads electricity supply due to
tremendous growth in air conditioning, thus tripping line breakers.

Natural causes reported as air contamination, trees, ice, no rain, as well as any incident reported
as transmission line failure, which may or may not refer to natural causes, form together only
thirty five percents of total power loss incidents. Defective equipment is responsible for forty
six percent of power loss incidents and is the main reason for power losses. Seven percent of
outages occurred due to automotive accidents. The reason of additional twelve percent is
unclear.

Although most installations are equipped with Uninterruptible Power Supply (UPS) systems, no
single UPS or its battery failure was reported. In some cases the power failure occurred after
depletion of UPS batteries.

Till late eighties, year by year, the arrival of first autumn storm was accompanied by collapsing
of defective UPS systems and particularly worn out backup batteries. No UPS Company had
enough staff, or enough batteries to deal with all irate calls from customers. The chaos stopped
when microprocessor based UPS control was introduced in early nineties, enabling automatic
testing of UPS systems including batteries, by performing periodic power outage simulation
exercises. The exercising enabled detection of defective systems, correction of the UPS and
replacement of defective and weak batteries. All these preventive actions were performed when
mains power was still available, before the stormy weather season.

Equipment malfunction diagnosis indicates that nature is not to be blamed. Similarly to the
described initial experience with UPS sytems, most of the studied power equipment, which
failed during storms was revealed to be already defective, and couldn't perform within its
designed limits. Lightning and switching voltages generated in the grid are generally attenuated
and clamped to the insulation levels of line isolators and surge protective devices. Healthy
transformers and cables should be able to withstand these voltage levels, and backup generators
should start when needed.

Performance of proper preventive maintenance can solve most of power failure problems.
Simple, cost effective monitors based on technologies such as Partial Discharge (PD) and
Infrared tomography are able to detect transformer defects, and allow scheduling corrective
actions in time. Power outage simulation exercising can reveal generator's starting problems.
PD methods, Power Factor measurements, as well as other monitoring methods, offered by
test instruments manufacturers, can alarm before the stormy season, about defective
underground cables, which require treatment.

UPSonNet study reveals that most power outages occur in stormy season, mainly because of
defective equipment, which fails in harsh environment. Such outages, do not happen due to acts
of God but due to negligence of humans, and can be avoided by proper maintenance service.
Regular maintenance schedule, exercising and monitoring can foresee possible problems, which
can be solved before the storms come.

Forty two major worldwide Power Failure reported incidents were analyzed by UPSonNet. All
occurred during February 2009, each affecting thousands up to hundreds of thousands people.
The study results indicate that most failures are due to defective equipment that failed in Stormy
Weather. Proper preventive maintenance could have eliminated most defects and the associated
power failures.

Normally, during the dry period, contamination which includes electrically conductive materials
is collected on power line insulators. Rains and storms close the electric path causing shorts
and arcs, tripping line breakers. Sometimes utility poles catch fire due to the electric arcs.

Salt is used in some areas as part of winter road treatment, increasing the amount of
contamination spread by road vehicles kicking up salt from the roadway. This creates more
potential for electric arcs near freeways and major roads.

Trees are also a leading cause of power failures in winter. Winds and snow cause trees to fall.
The falling trees cut power lines. Some power lines create electric shorts and arcs between
adjacent power lines or from power lines to ground.

Lack of rain may affect power supply in places where considerable amount of power is
generated by hydropower. Kathmandu is now seeing severe power cuts, with no rain in the past
few months and decreasing water level in rivers feeding the hydropower plants.

Excessive heat, as experienced in Australia in February, overloads electricity supply due to
tremendous growth in air conditioning, thus tripping line breakers.

Natural causes reported as air contamination, trees, ice, no rain, as well as any incident reported
as transmission line failure, which may or may not refer to natural causes, form together only
thirty five percents of total power loss incidents. Defective equipment is responsible for forty
six percent of power loss incidents and is the main reason for power losses. Seven percent of
outages occurred due to automotive accidents. The reason of additional twelve percent is
unclear.

Although most installations are equipped with Uninterruptible Power Supply (UPS) systems, no
single UPS or its battery failure was reported. In some cases the power failure occurred after
depletion of UPS batteries.

Till late eighties, year by year, the arrival of first autumn storm was accompanied by collapsing
of defective UPS systems and particularly worn out backup batteries. No UPS Company had
enough staff, or enough batteries to deal with all irate calls from customers. The chaos stopped
when microprocessor based UPS control was introduced in early nineties, enabling automatic
testing of UPS systems including batteries, by performing periodic power outage simulation
exercises. The exercising enabled detection of defective systems, correction of the UPS and
replacement of defective and weak batteries. All these preventive actions were performed when
mains power was still available, before the stormy weather season.

Equipment malfunction diagnosis indicates that nature is not to be blamed. Similarly to the
described initial experience with UPS sytems, most of the studied power equipment, which
failed during storms was revealed to be already defective, and couldn't perform within its
designed limits. Lightning and switching voltages generated in the grid are generally attenuated
and clamped to the insulation levels of line isolators and surge protective devices. Healthy
transformers and cables should be able to withstand these voltage levels, and backup generators
should start when needed.

Performance of proper preventive maintenance can solve most of power failure problems.
Simple, cost effective monitors based on technologies such as Partial Discharge (PD) and
Infrared tomography are able to detect transformer defects, and allow scheduling corrective
actions in time. Power outage simulation exercising can reveal generator's starting problems.
PD methods, Power Factor measurements, as well as other monitoring methods, offered by
test instruments manufacturers, can alarm before the stormy season, about defective
underground cables, which require treatment.

For additional information about overcoming outages in stormy weather, see Study Results.

Carrying on When Weather Storms