September 27, 2022

Anatomy of a Power Outage

Electricity is a service we often take for granted – until there is an outage. This is when we realize just how much we rely on it to power almost everything we do.

To understand a power outage, it helps to know how the electricity grid works. The main components are generation, transmission, and distribution.

  • Generation: As the name suggests, Ontario Power Generation (OPG) is an electricity generator. The organization makes power using nuclear plants, wind farms and solar farms, and by harnessing the force of water (hydro) from places like Niagara Falls. Hydro is actually a bit of a misnomer as it implies electricity is only generated by water in Ontario when in actual fact our electricity comes from a mix of sources.  Generators can also include individuals or businesses that have installed solar panels on the rooftop of their home or other building and plug into the grid to supply power.
  • Transmission: Following the generation process, electricity is transmitted over distances at high voltages using transmission lines. This is primarily Hydro One, who takes the power generated by OPG and transmits it throughout Ontario via the large electrical towers, underground cables and transmission stations located across the province.
  • Distribution: Once power has been transmitted throughout the province, it is the job of distributors like Elexicon Energy and other utilities to deliver it to the individual homes, businesses, and institutions they serve. Distribution substations take the power from the transmission lines and further reduce the voltage so that it is safe for use in the home, business or facility they serve.

When power fails

A power outage can be caused by a fault, disruption, or equipment failure at any point in the grid. When this happens, all services downstream of the outage get bumped offline. If a tower line topples over, as happened during the 2013 ice storm, everyone on that circuit loses power.

When there is a major power outage event as what happened on May 21 when severe storms produced an F2 tornado that swept through Uxbridge, it is all hands on deck as each part of the electricity grid was affected. Each organization activates their emergency restoration plan, collaborating to systematically prioritize the repair work.

Service restoration priorities

Image - Power Outage Restoration

The emergency restoration plans prioritize the repair work as follows:

  1. Hazardous situations – If there are downed, live power lines that have fallen across roadways, cars or homes, or if equipment has caught fire, these are tackled first to secure the area. The safety of the public as well as the field crews is a top priority.
  2. Critical customers – Next, power is restored to critical community services such as hospitals, fire, police, water treatment and other essential infrastructure.
  3. Major circuits – In surveying power disruptions, the goal is to restore electricity to the largest number of people as quickly as possible. The electricity providers identify the equipment that serves the most people and begin the restoration efforts there. Where possible, they temporarily reroute power from equipment that is still functional to those areas that are without until the local repairs are complete.
  4. Smaller areas and individual customers – Finally, equipment that feeds smaller areas or outlying individual customers is addressed.