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Momentary Outages on the Power System

We have all experienced those annoying momentary interruptions to the electricity supply that set all of our digital clocks and displays flashing.  They typically will also disrupt any programming you may have set up on the many electronic devices that don’t have a battery backup.

The momentary outages are actually meant to happen.  This is the way the system protection is set up.  The system has always operated this way but is more noticeable now because of the proliferation of electronic devices and appliances.  A lot of outages are temporary in nature and the electric system will clear the temporary fault and reset the system similar to re-booting a computer that is not operating properly.  Otherwise a temporary fault would result in longer duration outages.

To minimize the effect of these outages when buying your electronic devices try to purchase one with a battery backup that will keep the device program and clock in tact through a short momentary outage.  Other more sensitive equipment should be protected by a UPS (uninterruptible power supply) that will ride through the short interruptions and also allow a controlled shutdown (i.e., for computer programs) during a longer outage.  Most electronic supply stores will be able to give you advice on the right equipment to purchase.

There are many reasons that cause a temporary outage, some obvious some not so.  Lightning will often cause a temporary outage during a storm.   Sometimes the storm can be happening down by Lake Ontario and cause a transmission line to disconnect and we may see the effects here in Peterborough.  Tree limbs can contact a line either in a thunder or wind storm or break off during a nice day for no apparent reason.  A vehicle may hit a pole and shake the overhead line but not hit hard enough to cause any damage but still produce a momentary outage.  The most prevalent cause in Peterborough this year to date is animal intrusions.  We are blessed to live in a City with thousands of trees and lots of green space but the downside is that there is large population of squirrels, birds and raccoons that seem to enjoy causing havoc with our overhead lines.  They seem particularly active this year.  Peterborough Distribution has over 384 km of overhead lines in our Peterborough, Lakefield and Norwood service areas.

This year we have experienced a higher than normal number of these annoying momentary interruptions on our system and particularly in some areas of the east, north and downtown areas of Peterborough.  A review of the causes has found that 46% of them have been caused by animal intrusions, 30% by storms, 10% by trees, 10% by defective equipment and 4% of unknown origin.

Recently, we have undertaken a patrol of the overhead lines in question and have taken some actions to try to improve the situation.  We have removed some suspect tree limbs and will undertake a replacement program for our animal guards during the latter part of the year.

August 2012