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Adequacy is the ability of the electric system to meet peak demand of customers at all times, taking into account any scheduled and reasonably expected unscheduled outages of system elements.

Bulk transmission system: The bulk transmission system is similar to the provincial highways, allowing for the movement of large amounts of electricity across the province. The bulk system, often referred to as the backbone, is comprised of high-voltage transmission lines that interconnect the large remote generating stations (in the Peace and Columbia), with the major demand (load) centres in the Lower Mainland and on Vancouver Island. Bulk transmission is 230 kV or higher.

Capacity: The amount of electricity that a transmission facility can transfer reliably at any given time.

Circuit: A conductor or a system of conductors through which electric current flows and can be automatically segregated by circuit breakers or fuses.

Conductor: A substance or body, usually in the form of a wire, cable or busbar, that allows a current of electricity to pass continuously along it.

Constraint: A restriction on a transmission system or segment of a transmission system that limits the ability to transmit power between various locations.

Contingency: An event occurring on the transmission system that results in the loss of a system element.

Current: Flows of electricity passing through a conductor, measured in amperes. Current can either be alternating (AC) or direct (DC).

Distribution: The delivery of low-voltage electricity from substations to homes and businesses in communities across BC.

Fault: An event occurring on an electric system where abnormally high current flows resulting in the operation of a protection device or such as a short circuit, or a total interruption of an electrical circuit.

Generation: The creation of electricity. Different generators use different fuels. Water is used at hydroelectric facilities; turbines capture wind energy to create electricity; and solar panels produce solar power. Other fuels, like wood waste from pine beetle infested timber, are also used to generate electricity.

Gigawatt: a thousand megawatts or one million kilowatts.

Gigawatt hour: One million kilowatt-hours - an amount of electric energy that will serve about 100 residential customers for one year.

Grid: The layout of an electrical transmission system.

Impedance: The opposition in an electrical circuit to the flow of alternating current (AC).

Interconnected system (also known as "interties"): The interties are high-voltage transmission lines that connect different transmission systems. The BCTC transmission system is interconnected to the transmission networks in Alberta and Washington State as well as other utilities in BC (e.g., Alcan and FortisBC). These interties provide access to other sources of generation, the opportunity for trade, improve the overall reliability of the system by providing backup resources and improve power quality.

Limiting element: The device in a system that has the lowest energy rating, thereby setting the maximum amount of energy that can be transferred.

Load: The amount of electricity required by a customer or group of customers as measured by an electrical metre.

Load forecast: The expected customer electricity requirements that will have to be met by the electrical system in future years.

Load shedding: Removal of pre-selected customer demand from a power system, as a result of the occurrence of an abnormal condition, in a effort to maintain the integrity of the system and minimise overall customer outages.

MW: Megawatt(s) = 1 million watts or 1000 kilowatts of real electrical power.

MWh: Megawatt hour(s). A unit of energy.

Path: A transmission line or set of lines that carry energy from one region to another.

Peak demand: The maximum load during a specified period of time.

Radial transmission: A transmission system that is not networked and does not provide multiple parallel flow paths.

Regional Transmission: The regional transmission systems are similar to regional road networks, moving electricity to where it is needed within specific geographic areas, such as between Lower Mainland communities or across Vancouver Island.

Reliability: Electric system reliability can be addressed by considering two basic and functional aspects of the electric system:

i) Adequacy: The ability of the electric system to supply the aggregate electrical demand and energy requirements of the customers at all times, taking into account scheduled and reasonably expected unscheduled outages of system elements; and

ii) Security: The ability of the electric system to withstand sudden disturbances such as electric short circuits or unanticipated loss of system elements.

Rights-of-way: The land rights acquired by a utility to allow the construction and operation of electrical transmission or distribution facilities.

Substation: Substations route and control electrical power flow, transform voltage levels, and serve as delivery points to industrial customers.

Thermal rating: The maximum amount of electrical current that a transmission line or electrical facility can conduct over a specified time period before it sustains permanent damage by overheating or before it violates public safety requirements.

Transfer capacity: The ability of interconnected electric systems to move or transfer power in a reliable manner from one area to another over all transmission lines (or paths) between those areas under specified system conditions. The units of transfer capability are in terms of electric power, generally expressed in megawatts (MW).

Transformer: An electrical device for changing electricity from one voltage to another.

Transmission: The movement of high-voltage electricity from where it is produced to where it is needed.

Transmission circuit: A set of wires energized at transmission voltages extending beyond a substation which has its own protection zone and set of breakers for isolation.

Transmission losses: The power lost in transmission between one point and another. It is measured as the difference between the net power passing the first point and the net power passing the second point.