Power Technology Glossary Part 2
Breaking Current: The highest current which can, without doing serious damage to the device, be passed through a circuit breaker.
Bridge Rectifier: A type of rectifier consisting of four diodes connected so that they form a bridge.
Bucking: Reducing or compensating the effect of an undesirable voltage or voltage variation by creating an opposite voltage or voltage variation.
Buck-Boost transformer: A transformer providing simultaneous bucking and boosting capabilities.
Capacitor: An electrical device for storing electrical energy in the form of an electrical charge, used as a reactance in series- or parallel-resonant circuits.
Circuit Breaker: A device which is connected in a circuit to protect it from damage due to an overload.
Clamp Meter: An instrument for measuring current by clamping it around the circuit conductor.
Closed-Loop Control: A control system in which the output has a direct effect on the input.
Commutating: The process of alternately switching the current between two separate paths.
Core Balance: An output transformer that is designed to minimize the serious electrical distortion by using winding cores of equal magnetizing forces and equal electric resistance.
Delta Connection: The three-phase connection of electrical windings in which the three windings are connected end to end creating a closed delta.
Differential Protection: A protection system in which the current flowing into and out of an equipment is monitored to detect any abnormality.
Distribution System: A network of electrical lines, cables and other equipment for supplying electricity from generators to consumers.
Disturbance: Any sudden change in an electrical parameter, either temporary or permanent.
Drawout Circuit Breaker: A type of circuit breaker which can be withdrawn from one end of a vertical cabinet into the other.
Draw-through Air Circuit Breaker: A type of air-blast circuit breaker in which the arc quenching gases are drawn through the contacts by a fan after the breaker has been operated.
Dynamic Braking: The process whereby energy stored in a motor is dissipated by closing the armature circuit suddenly.
Earth Fault: An earth fault is an electric fault that exists between a conductor and the earth resulting in the current being conducted to earth.
Earth Leakage Currrent (ELC): An electric current that passes through an earth connection caused by a fault in the equipment or the insulation of the cables.
Electromagnetic Pickup: An electrical device which detects and amplifies small voltage signals generated by an external electromagnetic field.
Electronic Load: An electrical device used to vary the load in an electrical circuit.
Electronic Overload Relay: A relay which trips if the current drawn by a motor exceeds a preset value.
Energy Consumption: The amount of energy consumed by a device or system over a period of time.
Equalizing Current: A current whose magnitude and duration is determined by the need to equalize the voltage, or harmonics, between several separate sources of supply.
Fault Current: The maximum current which can flow in the event of a fault, such as a short-circuit.
Fault Level: The maximum fault current which can flow under operating conditions.
Frequency Response: The ability of a device or system to respond to and transmit a signal of a particular frequency.
Ganged Arrangement: A type of electrical arrangement in which two or more components are connected and controlled together.
Ground Fault: A fault in which current leaves a conductor and flows directly to the earth.
Ground-fault Current: The current which flows when a fault occurs between a phase conductor and the ground.
Ground Loop: A type of circuit which is formed when the return path for current is formed via the earth.
Ground Voltage Drop: The difference in potential between two points due to the current flow through the earth.
High Voltage: Any voltage over 1000 volts AC or 1500 volts DC.
Islanding: A term used to describe when a section of power system is disconnected from the larger system and will be operated as an independent network.
Insulation: An insulation layer between two conductors which prevents electricity from flowing.
Insulation Resistance: The resistance between two conductors which prevents the flow of electricity.
Power Factor: The ratio of active power to apparent power in an alternating current system.
Power Quality: The quality of power supplied by an electric utility company.
Power Supply: A device for providing electrical energy to an electric load.
Protective Relay: An electrical device which senses faults, abnormalities, or other hazardous conditions and causes an electrical circuit to be automatically disconnected from the power supply.
Reactance: The opposition to a signals passage caused by inductance, capacitance or resistance.
Rectification: The process of converting alternating current (AC) to direct current (DC).
Residual Voltage: The voltage remaining after a power system has been subjected to a fault or transient.
Ring Main System: A closed loop of runs of cables that forms a power distribution network.
Series Resonant Circuit: An electrical circuit in which the inductive reactance is equal and opposite to the capacitive reactance.
Single-Pole Switching: A switch which turns on or off only one of the two contact points of a circuit.
Sine Wave: An alternating current of a single frequency which has the same shape as a sine function.
Soft Starting: The process of gradually increasing the voltage applied to an electric motor in order to reduce the inrush current.
Soft Stop: The process of gradually reducing the voltage applied to an electric motor in order to reduce the outrush current.
Static Frequency Converter: A type of frequency converter that does not require a rotating component.
Substation: An installation designed to house two or more pieces of equipment for the purpose of distribution of electrical power.
Surge: An abnormal voltage or current in an electrical circuit.
Three-Phase Current: An electrical current which flows through three conductors, each at a different phase.
Thyristor: A semiconductor device which controls electric current by allowing the current to flow in one direction only.
Torque Ripple: The difference between the output of a motor under load and from a motor running at no load condition.
Transducer: An electrical device that converts one type of energy into another such as electrical signals into mechanical motion, or mechanical motion into electrical signals.
Transformers: An electronic device used to increase or decrease the voltage, current or impedance of an AC electrical circuit.
Transient Response: The time taken for a device or system to respond to a change in its environment.
Triac: A three-terminal semiconductor device which acts as a switch to control the flow of electrical energy.
Undervoltage Protection: A protection system that trips or opens circuit breakers when the voltage falls below a certain level.
Voltage Sag: A reduction in the supply voltage level.
Voltage Surge: An increase in the supply voltage level.
Waveform: The shape of an AC voltage or current as it varies over time.
Zero-Crossing Relay: A type of relay which operates when the alternating current passes through zero.
