Electrical Terminology

Alternating current (AC)

Electric current that reverses its direction of flow at regular intervals.

Ampere (A)

The unit of measurement for electric current.

Cycle

Electric current flowing in one direction and then reversing its direction.

Demand

The size of any load, expressed in kilowatts, averaged over a specified period of time.

Direct current (DC)

Electric current that flows in one direction only.

Distribution system

The wood poles, conductors, and transformers that deliver electricity to customers. It transforms high voltages to lower, usable levels. Electricity is distributed at 120/240 volt (V) for most residential customers and 120 V to 600 V for the majority of industrial and commercial customers.

Electric current

The flow of charged particles (electrons) through a conductor (for electricity, a cable).

Energy

The ability to do work. Electrical utilities sell electrical energy to their customers who, in turn, convert this energy into a desirable form – such as work, heat, light or sound.

Export load

Any electricity that is generated in excess of provincial needs and is sold to out-of-province energy markets.

Firm power

Power (electricity) that must be supplied as agreed under contract, even under adverse conditions.

Frequency

The number of completed cycles that an electric current or voltage goes through in one second. In Manitoba, the electric current completes 60 cycles in one second (60 hertz).

Generator

A machine that converts mechanical energy – such as a rotating turbine driven by water or steam or wind – into electrical energy.

Gigawatt (GW)

The unit of electrical power equivalent to one billion watts or one million kilowatts.

Interconnections

Power lines that interconnect one electrical utility's power system with another.

Kilovolt (kV)

The unit of electrical pressure, or force, equivalent to 1,000 volts (V).

Kilowatt (kW)

The unit of electrical power equivalent to 1,000 watts (W).

Kilowatt-hour (kWh)

The unit by which electrical energy is measured. For example, ten 100-W light bulbs switched for on for one hour would use one kilowatt-hour (1,000 W for one hour).

Load

The amount of electricity required by a system or piece of equipment at a given instant.

Megawatt (MW)

The unit of electrical power equal to one million watts or 1,000 kilowatts (kW).

Ohm

The unit of measurement of electrical resistance against the flow of electric current.

Peak load

Record of maximum amount of electricity used in a given time period.

Power

The rate of using electrical energy, usually measured in watts, kilowatts or megawatts.

Power grid

A number of interconnecting electrical power systems which link together electrical utilities covering a large geographical area.

Transmission system

The towers and conductors that transport electricity in bulk form from a source of supply to either local areas for distribution, or to power systems of out-of-province electrical utilities. Electricity is usually transported via transmission lines in amounts ranging from 66 kV to 500 kV.

Volt (V)

The unit of measurement for electrical pressure, or force, which causes electric current to flow.

Watt (W)

The unit of measurement for electrical power.