Control Systems & PLC's

Power Line

Taking Care of Power Equipment and Carrying On in Stormy Weather

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.

About the Author

Meir Portnoy is VP of UPSonNet –Information Source, Publishing about Power Protection and Power UPS field. Website includes Selection guides, UPS Industry prices, most extensive UPS Glossary and Essential UPS News, which update within minutes a day about important industry products, developments and trends.
For more information please visit UPSonNet.

Can I run the gas line and power line for my pool heater next to each other?

I need to dig to put my gas line and power line for my pool heater. Can these lines be ran together in the same underground hole?

The electrical code states they must be in separate trenches but the mechanical code states that its ok, so if your pulling permits, install only the electrical then call for your electrical inspection, then after its approved go ahead and run your gas in the same trench and call for your mechanical inspection.

I know its kinda stupid, but thats how its written, two different codes for two different trades.

If your not pulling permits go a head and put both in the same trench, just be sure to run your wires in conduit ( the grey pipe )

Storms Bring Down Power Lines In Lancaster County