Peak Load Demand

What is Peak Load Demand?

Peak load demand in an electricity system is the total amount of electricity required by all power consuming devices at the time when demand for electricity is highest. Peak demand periods are generally at predictable times of the day and are usually quoted as a fixed four hour period. A commonly quoted peak period is in the evening peak from 4 pm to 8 pm when people get home from work at the end of the day and switch on many electrical appliances simultaneously.

Power networks can have other peak demand periods at other times of the day, related to industry, business and the weather. A common industrial peak demand is 12 noon to 5 pm weekdays.

Electricity distribution companies are adopting TOU charges in an attempt to change consumer behavior, to reduce peak load demand during peak periods, as an alternative to upgrading costly power lines to manage the growing peak loads which occur less than 20% of the time

What can cause spikes in demand?

Spikes in power demand commonly occur during extreme weather events, hot and cold. Power distribution controllers are required to constantly monitor demand across power networks and have additional generating capacity available to cover the unusual events leading to spikes in demand.

Measuring Peak Demand

Power distribution companies are moving, more and more, to pricing electricity using Time Of Use (TOU) tariffs. These TOU tariffs are intended penalize customers who are heavy power users during peak load periods when power distribution systems are reaching their maximum carrying capacity. The introduction of Smart Power meters allows power companies to remote measure the amount of power consumed at different time periods, charged at different rates per kilowatt hour. It is already common in Australia for business to have at least three tariff rates for Off Peak, Shoulder and Peak periods.

Power quality logging is a very effective way to get a clear picture of a business’ electricity load profile over twenty four hours, matched against the different tariff periods they are charged. This can also be repeated over several days, or a business cycle.


Analysing a Business’ Power Demand Report

Load profile charts extracted from a power quality logging exercise can be marked up with relevant TOU tariff hours to reveal the business’ power consumption relationship to different tariffs. The power quality professional will include demand profile information in a comprehensive power quality report.

Business managers who can continuously monitor and measure the power demand in their business will become very aware of where and when the business is using electricity and, if necessary, can change operating procedures and processes to reduce overall power costs.

Solutions for Peak Demand charges

Electricity cost reduction does not mean reducing the quality of a business’ output, or the comfort of workers. Costs can be managed in a smarter way through knowledge gained and a ’Management By Objectives’ approach. An effective strategy for reducing power costs is to:

  1. Arrange for a complete audit of power consuming devices, noting their general age and condition,
  2. Then arrange to have a power quality audit which will help to identify power hungry devices and reveal any power quality issues within the business’ power circuits,
  3. Develop a business strategy prioritising a number of actions required to reduce overall power consumption.

Examples of actions that might be considered

  • Load shifting, moving some operations to off peak time periods,
  • Install permanent power monitoring with the capability of alarming and notifying when predetermined power consumption levels are exceeded during peak periods
  • Install power factor correction equipment to improve the efficiency of inductive loads,
  • Install harmonic power filters on circuits identified as having high harmonic disturbances,
  • Install motion sensitive and photo electric sensitive lighting systems,
  • Change out old power hungry machinery.