Monitoring a.c. powerlines, in both overhead and underground and primary and secondary applications, is useful to electric utility companies in order to anticipate outages which occur due to faulty equipment and overloads on a.c. powerlines and which result in loss of service for potentially a large number of end customers. The potential for an outage and for the loss of the greatest number of customers is increased during peak periods when power usage is at a maximum and delivery of continuous power is most critical. Outages caused by faulty and overloaded lines are expensive to repair, costly to the electric utility company in terms of dollars lost for lost service and in terms of damage to the utilities reputation and can be dangerous for utility company employees.
The effects of an unexpected outage as a result of a faulty or overloaded powerline are exacerbated if the powerline is underground. Replacing a damaged underground line requires more man hours and increased safety precautions due to the fact that the majority of work required occurs underground in cramped, sometimes wet, and always less than ideal conditions. As a result, repairing such a damaged underground line is even more costly, time consuming and dangerous.
Thus, a.c. powerline sensors which sense electrical conditions, such as power, voltage and current are very useful to electric utility companies in monitoring a.c. powerlines in order to better anticipate the likelihood of an unexpected outage occurring due to faulty and overloaded lines. If the electric utility companies are able to monitor the conditions on the powerlines, they are better able to perform maintenance on and replacement of powerlines which are likely to become deenergized as a result of an overload or fault, thereby lowering the number of unexpected outages. By replacing and maintaining such equipment the utility company can significantly decrease outage time to the end customer. The costs associated with repair or replacement of damaged cables will also be decreased. The cost of replacing or repairing damaged cables may be significantly greater in comparison to normal scheduled maintenance or replacement because of the overtime pay involved.
However, conventional commercial powerline sensors typically require an invasive electrical connection to the power circuit that is being monitored. This type of installation is expensive for the utility company, potentially dangerous for the installer and can cause a service interruption for the end user. Due to these limitations, powerline sensors have not been widely used in the electric utility industry.