Glossary of Electric Utility Industry Terms
Impedance – The total of all resistance, inductive reactance and capacitive reactance in an electrical system or circuit. Each of these quantities reduce current flow; therefore, the more impedance there is, the less the current flow will be. Impedance is represented by the letter Z. (EUSO, CAEDS, EDS, IESO, System operator classes)
Independent System Operator – An organization responsible for the second-by-second operation and control of the transmission systems of several utilities. It is “independent” of each utility’s control, and serves each utility equally. (EUSO, System operator classes)
Inductance – The ability of a circuit or device to store energy in the form of a magnetic field. Inductance is measured in Henrys. One coil or device has one Henry when current changing at one Ampere per second produces 1 Volt. Henry is named after Joseph Henry (1797 – 1878). Joseph Henry was one of the scientists who discovered that magnetic fields can be used to produce alternating current. Inductance is represented by the letter L.
Inductive Reactance – A quantity that reduces current flow in an alternating current system. Alternating current produces an increasing and decreasing magnetic field. This increasing and decreasing magnetic field induces ( hence the term “inductive”) a voltage that impedes the ability of current to change direction. This characteristic of impeding current changing direction is inductive reactance. Inductive is represented by X L. X is for reactance and L is for inductance.
Inverter – An electrical device that converts direct current to alternating current.
Investor Owned Utility – An investor-owned utility (IOU) is an utility that is owned by its stock holders. The stock holders elect a board of directors and the board of directors hires upper management. IOU are regulated by the state regulatory commissions in each of the states in which the IOU operates. These state commission are called the Public Utility Commission, the Public Service Commission, the Bureau of Labor and Industry, etc.
IOU – See investor owned utility
ISO – See Independent System Operator.