The Electricity Basics
You can always go to Google, Wikipedia or some other source for this but let me try to explain it briefly. Electricity is an essential commodity for our society and should be treated with the utmost respect due to its lethal potential when used incorrectly.
Voltage
It is the electromotive force in an electrical circuit measured in a unit called Volts. You can’t see electricity so it is a difficult concept for some people. Comparing it to something you can see, it is analogous to water pressure in your home plumbing. With your tap shut off, the pressure doesn’t do anything but it has the potential. Voltage levels are standardized in Canada as outlined by the Canadian Standards Association (CSA).
- High Voltage transmission lines in the bulk electric system in Ontario operate at 500,000 and 230,000 volts
- A typical residential electrical service will be rated 240 volts with a split that provides 120 volts.
Current
Current is the flow of electrons and is measured in Amps. It is analogous to the flow of water in your plumbing at home.
- A typical 120 volt wall receptacle is rated for 15 amps in accordance with CSA
- It only requires 10 milliamps (0.01 amp) to shock a person and 100 milliamps (0.1 amp) to stop the human heart.
Power
In electrical terms it is an instantaneous measure of voltage and current in a circuit and called ‘watts’. It represents the basis for performing work measured at a specific instant in time. You will see this unit of measure when referring to generator capacity, light bulb size, heater rating etc.… In your home a typical wall outlet is rated for 15 amps at 120 volts which is 1,800 watts of power. A hair dryer may be rated at 1,500 watts. A common incandescent light bulb size is 60 watts. The LED high efficiency bulb will be 13 watts but produce the same amount of light as a 60 watt incandescent. When you go to larger devices you will see prefixes which represent multiples of 1,000 in order to eliminate the digits with least significance.
- 1 kilo-watt is 1,000 watts denoted as kW
- 1 mega-watt is 1,000,000 watts denoted as MW
- 1 giga-watt is 1,000,000,000 watts denoted as GW
- 1 tera-watt is 1,000,000,000,000 watts denoted as TW
- The power output rating of the original Sir Adam Beck generating station in 1921 was 1,123 Megawatts.
- The estimated total generating capacity in Ontario for 2017 was 36,495 Megawatts.
Energy
Energy is the unit of measure for power across time. It is a measure of work performed. Mathematically it is power multiplied by time. It is how residential ratepayers are billed for electricity use. The standard measure for electrical energy is hourly and is the watt-hour. If you leave a 60 watt bulb on for one hour it will consume 60 watt-hours of energy.
- The typical residential electricity user in Ontario consumes 750 kilo-Watt-hours (750kWh) of energy per month. It is measured and recorded by a Measurement Canada approved metering device.
- The energy used in Ontario in 2017 was approximately 132 Tera-Watt-hours (132TWh).
Utilization, Capability or Capacity Factor
Utilization, capability or capacity factor refer to the same measure. It is a measure of how much an asset is used over time compared to its rated capability.
- If a generator ran at its fully rated output all of the time it would have a 100% capability factor.
- A generator operating at half of its rated output all of the time would have a 50% capability factor.
It helps to know the basic terms since we are paying for energy and a couple of key factors influencing the cost are related to power (generator capacity, load demand) and utilization or capability factor (generators and TOU rates).
Derek Hughes
