Understanding Electrical Terminology

Electrical Terminology

• Alternating Current (AC) is an electric current that reverses direction at regular intervals.
• An Ammeter measures electrical current in amperes and is connected in series within a circuit.
• Ampacity represents the maximum current a conductor can handle before deterioration.
• Ampere-Hour (Ah) is a battery capacity unit, calculated by multiplying current in amperes by the time in hours.
  • A battery delivering 5 amperes for 20 hours has a 100 ampere-hour capacity.
• Ampere (A) measures electric current intensity; one ampere equals one coulomb per second.
• Apparent Power, measured in volt-amperes (VA), equals the product of RMS voltage and current.
• Armature refers to the moving component of generators/motors.
  • Armatures consist of conductors rotating in a magnetic field to produce voltage or force through electromagnetic induction.
  • Pivoted points in generator regulators are armatures.
• Capacitance is the ability to store electrical charge, measured in farads as the ratio of charge (coulombs) to voltage (volts).
• A Capacitor stores electrical charge, made of conductor pairs separated by an insulator, and filters voltage spikes.
• Circuit is a closed path that facilitates electron flow from a voltage/current source, in series, parallel, or combined configurations.
• A Circuit Breaker is a device that automatically halts current flow.
  • After overload/failure correction, it resets to restore service and uses protective relays to safeguard circuits from faults.
• A Conductor is a material allowing free electric current flow.
  • Conductive materials, like metals, have low resistance; copper and aluminum wires are common conductors.
• Corona discharge arises from fluid ionization surrounding a charged conductor.
  • Spontaneous corona discharges occur in high-voltage systems unless electric field strength is limited.
• Current (I) is electric charge flow through a conductor, measured in amperes, analogous to water flowing in a pipe.
• Cycle signifies the change in an alternating electrical sine wave from zero to positive peak, back to zero, to negative peak, and back to zero.
• Demand is the average power/related quantity over a specified period.
• Dielectric Constant measures how well a substance stores electrical energy in an electric field.
• Dielectric Strength is the maximum electric field a material withstands without insulation failure.
• A Diode is a two-terminal semiconductor allowing current flow in one direction when the anode is positive relative to the cathode.
• Direct Current (DC) flows in only one direction.
• Electrolyte is a substance that, when in solution, dissociates into ions and conducts electrical current, such as sulfuric acid in a battery.
• Electromotive Force (EMF) is a potential difference that can give rise to an electric current, measured in volts.
• An Electron is a negatively charged subatomic particle orbiting an atom's nucleus.
• Electron theory explains electricity's nature and "free" electron exchange between atoms; explains current flow direction.
• Farad measures capacitance; one farad equals one coulomb per volt.
• Ferroresonance (nonlinear resonance) occurs in circuits with nonlinear inductance and series capacitance with a disturbance.
  • It can cause overvoltages/overcurrents, risking transmission/distribution equipment and personnel.
• Frequency measures cycles per second in Hertz (Hz); 1 Hz is equivalent to one cycle per second, and 60 cycles per second is 60 Hz.
• A Fuse is a wire strip that melts and breaks a circuit when current exceeds a safe level, preventing further damage.
  • Fuses are replaced with the same size and rating after fixing the issue.
• A Generator converts mechanical energy to electrical energy.
• Ground serves as a reference point, a return path, or a direct connection to Earth in a circuit.
• Ground Fault Circuit Interrupters (GFCI) de-energize a circuit if ground current exceeds a limit, protecting personnel.
• Henry measures inductance; one henry causes of one volt if current changes at one ampere per second.
• Hertz (Hz) measures frequency, replacing cycles per second (cps).
• Impedance is a circuit's opposition to current flow with applied voltage, encompassing magnitude and phase in AC circuits.
• Inductance is a conductor's property where current changes induce voltage in itself (self-inductance) and nearby conductors (mutual inductance), measured in henries (H).
• An Inductor is a wire coil around an iron core, with inductance proportional to coil turns.
• An Insulator is a material resisting electric current flow, protecting equipment and life.
  • Insulative materials include glass, rubber, air, and plastic.
• An Inverter converts direct current to alternating current.
• Kilowatt-hour (kWh) is power (kW) multiplied by time (hours), with 1 kWh being 1000 watt-hours.
  • A 100W bulb used for 4 hours consumes 0.4 kWh of energy.
• A Kilowatt-hour Meter measures electrical energy use.
• Kilowatt (kW) equals 1000 watts.
• A Load consumes electrical energy, including lights, transformers, heaters, and electric motors.
• Load Rejection is a sudden load loss causing over-frequency in generating equipment.
  • Load rejection tests confirm the system's ability to withstand load loss and return to normal operation with its governor.
  • Load banks are used in these tests during commissioning.
• Mutual Induction induces voltage in a second coil by changing current in one coil.
• Ohm (Ω) measures resistance; one ohm occurs with one ampere of current flow and one volt of potential difference.
• Ohm's Law is the equation showing the relationship between current, voltage, and resistance (V=IR).
• An Ohmmeter measures resistance in ohms.
• An Open Circuit has broken continuity, blocking current flow, analogous to a closed valve in a water system.
• A Parallel Circuit has multiple paths for current flow, with each load receiving full circuit voltage, and total current equaling the sum of branch currents.
• Piezoelectricity is electric polarization in a substance (especially certain crystals) from mechanical stress (pressure).
• Polarity refers to the positive (+) and negative (-) ends of magnets or electrical components.
• Power is rate of electrical energy transfer, measured in watts.
• Power Factor represents the ratio of true power to the product of RMS values of current and voltage in an AC circuit.
• Protective Relay trips a circuit breaker upon detecting a fault.
• Reactive Power sustains electric/magnetic fields in AC devices, measured in VARs and existing when current and voltage are out of phase.
• A Rectifier converts alternating current into direct current by permitting current flow in only one direction.
• A Relay is a small electrical coil switch used to manage larger currents.
• Reluctance is the resistance a magnetic circuit offers to magnetic force lines.
• Resistance opposes electric current flow, analogous to friction in a water pipe, and is measured in ohms.
• A Resistor is a device, typically wire or carbon, that provides resistance to current flow.
• The Rotor is the rotating components in machines like generators, motors, or alternators.
• Self Induction creates voltage in a coil when its current changes.
• A Semiconductor's conductivity falls between insulators and metals, influenced by impurities/temperature.
  • Silicon is used to make semiconductors.
• A Series-Parallel Circuit contains components in both series and parallel arrangements.
• A Series Circuit provides only one path for electricity, with all current flowing through all loads.
• Service conductors/equipment connects the electrical supply network.
• A Short Circuit occurs when parts of a circuit contact, diverting current.
• Solid State Circuits use semiconductor devices like transistors/diodes/silicon-controlled rectifiers.
• A Transistor is a semiconductor with three connections, used for amplification and rectification.
• True Power is measured in Watts.
  • In DC or AC circuits with pure resistance, voltage and current are in phase.
• Vars measure reactive power, representing the imaginary part of apparent power in volts and amperes.
• A Variable Resistor is adjustable across a range of values.
• Volt-Ampere (VA) measures apparent power as a product and of rms voltage and current.
• Volt (V) measures voltage; one volt drives one ampere against one ohm of resistance.
• Voltage is electromotive force, analogous to water pressure, measured in volts.
• A Voltmeter measures electrical current force in volts, by measuring the potential difference between points in a circuit.
  • Voltmeters have high resistance and connect across points for measurement.
• Watt-hour (Wh) measures electrical energy, equivalent to one watt consumed for one hour.
• Watt (W) measures electric power, equivalent to one joule per second in a circuit with one volt and one ampere.
• A Wattmeter measures electric power in watts.
• Waveform represents electrical cycles graphically, showing amplitude variation over time.