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Voltage Reduction Tests: Ensuring Reliability and Peace of Mind

Wiarton Willie’s recent Groundhog Day prediction of six more weeks of winter may find you dreaming of enjoying those hot sunny summertime days relaxing on the deck, sunbathing on the beach or taking a refreshing dip in the pool. And yet we all know, energy usage usually goes up on days of extreme heat with temperatures of 30°C or more, especially for those of us who use air conditioning, which puts increased strain on the electricity system. So what happens when there is a high demand on electricity combined with limited supplies of reserve power? There is a potential for blackouts.

But don’t fret! To prepare for the high electricity demand days of summer, help prevent the occurrence of rotating blackouts and maintain reliability of Ontario’s electricity system, the Independent Electricity System Operator (IESO) conducts routine voltage reduction tests. Since the next test is planned for March 6th, here’s what you need to know about how voltage reductions and testing affect you.

What is a voltage reduction?

A voltage reduction is one tool used by the IESO in emergency situations to maintain provincial grid reliability when demand on the electricity system exceeds the available supply. Voltage reductions lower the demand on electricity quickly, which minimizes the likelihood of service interruptions.

Are voltage reductions only used on days of extreme heat?

Voltage reductions can be used during a variety of unplanned situations and emergencies to maintain the reliability of Ontario’s electricity system. For example, on July 9-10, 2013, the IESO implemented a five percent voltage reduction in the Toronto area to protect transmission equipment while electricity was being restored to the communities affected by flash flooding.

How do voltage reductions and tests affect consumers?

Voltage reductions have minimal or no noticeable impact on the general public, because the voltages are still within established industry standards for electrical equipment used by residential, commercial and industrial consumers. Thus, you should not notice any impact on your electricity usage during voltage reduction tests.

Why are voltage reduction tests important?

Since all consumers will be impacted during a real voltage reduction event, voltage reduction tests provide test participants the opportunity to identify and fix equipment problems before an unplanned event. Broad participation leads to a better quality of test, which helps support the reliability of the electricity system.

What is the purpose of voltage reduction tests?

The IESO uses voltage reduction tests to:

  • measure and analyze how much power can be reduced through two levels of reduction;
  • identify and address any equipment problems among test participants caused by reduced voltage;
  • help keep IESO and market participants’ staff familiar with emergency procedures, and identify any deficiencies that may need correction.

How often are voltage reduction tests conducted?

Routine voltage reduction tests have been conducted approximately every 18 months for over 20 years in Ontario.

How long do voltage reduction tests last?

The IESO conducts two province-wide tests, a three percent voltage reduction and a five percent voltage reduction, which last approximately one hour each.

What is the impact of voltage reduction on the electricity system?

The amount of relief provided to the electricity grid is expressed as a percentage of Ontario’s demand. The last voltage reduction test exercise in August 2016 achieved the following results:

  • the three percent voltage reduction test resulted in an average reduction of 1.48 per cent in Ontario demand;
  • the five percent voltage reduction test resulted in an average reduction of 2.2 per cent in Ontario demand.

Can consumers request an exclusion from voltage reduction testing?

Alectra Utilities customers with concerns about public health and safety, potential damage to equipment, undue injury to the environment, or possible loss of production may request a temporary exclusion from voltage reduction tests a minimum of three days in advance. Visit the IESO website for more information about temporary exclusions from voltage reduction tests.

Emergency planning, training and testing including voltage reduction tests help the IESO maintain reliability of the provincial electricity system, which gives us all the peace of mind that we’ll have the power we need, whenever we need it.