Electrical Engineering Lecture Review – Vocabulary Flashcards

120 key vocabulary flashcards extracted from the lecture’s multiple-choice review, covering transformers, power systems, machines, electronics, protection, and Philippine electrical standards.

High-tension (HT) winding location in a transformer

Placed away from the core to reduce insulation stress.

Low-tension (LT) winding location in a transformer

Placed nearest the core for better heat dissipation and insulation economy.

Capacitance of a short transmission line

Usually neglected because the line length is too small for significant charging current.

Ohm’s-law characteristic curve

Linear; current is directly proportional to applied voltage at constant temperature.

Overcurrent protective device operating quantity

Current flow (excessive current triggers the device).

Maximum bends in a rigid conduit run

Four quarter-bends (360° total) between pull points or outlets.

Suspension insulator

Preferred type for high-voltage overhead-line applications.

Torque angle (δ) continuously increasing

Indicates an unstable power-system condition.

Essential condition for Ohm’s Law

Conductor temperature must remain constant during measurement.

Primary-line outages (PH Distribution Code)

Included in reliability-index calculations for distribution assets.

Half-duplex communication

Only one party transmits at a time on the same channel.

Base-load plant economic feature

High capital cost but low operating cost to supply continuous demand.

Peak-load plant economic feature

Low capital cost and high operating cost; used during demand peaks.

Effect of earth on line-to-ground capacitance

Capacitance increases because of the earth’s presence as a return path.

Skin and proximity effects

Phenomena that raise the effective AC resistance of conductors.

π or T equivalent

Either network can model a two-terminal transmission-line section.

VHF television band

Includes Channels 2 to 13 (54 – 216 MHz).

ACSR total strand formula

For (n-1) layers around a core: 3n² – 3n + 1 strands.

Tidal power

Most advantageous method of generating electricity from sea water.

Minimum spacing between two grounding electrodes

1 800 mm (per Philippine rules).

Parallel resonance branch currents

Inductor and capacitor currents are equal in magnitude (opposite phase).

PEMC (EPIRA)

Philippine Electricity Market Corporation – spot-market operator.

Load-sharing increase for a paralleled alternator

Raise its prime-mover (input) torque while keeping excitation constant.

Open-circuit (no-load) transformer test

Determines core (iron) losses and magnetizing current.

Coal-fired plant

Example of a conventional energy source.

Stator back-emf magnitude in a synchronous motor

Set primarily by DC field excitation level.

Typical speed of hydro-plant alternators

Medium speed (300-600 rpm) because of water-turbine characteristics.

Loss-free RLC transient

Sinusoidal (undamped) oscillation of current and voltage.

Series RC circuit at very low frequency

Behaves almost as a pure capacitor.

Distributed armature winding (alternator)

Improves output-voltage waveform by reducing harmonics.

Corona effect

Causes increased energy (power) loss on high-voltage lines.

RMS of a pure cosine wave

0.707 × peak (same as sine).

Device 32

IEEE function number for a directional power relay.

Luminous flux

Rate of light energy emission; measured in lumens.

Peak-load plant efficiency

Considered secondary; ability to meet peaks is primary.

Battery electrolyte test

Specific gravity measurement indicates state of charge.

Opened shunt-field of a DC shunt motor

Motor speed rises dangerously high (runaway).

Ideal full-wave rectifier efficiency

Approximately 81 % (theoretical 80.6 %).

Dummy coil (DC machine)

Unused armature coil inserted to maintain mechanical balance.

Circuit-breaker insulating oil roles

Cooling, insulation, arc quenching – NOT an interrupter element itself.

Electric field inside a hollow conductor

Zero; charges reside on the outer surface.

Residual magnetism

Essential for building voltage in a self-excited DC generator.

Delta circuit with one open resistor

Total power reduces by one-third.

Oscillatory RLC transient condition

Occurs when R < 2√(L⁄C) (under-damped).

Wave winding (DC)

Series armature winding used for high-voltage, low-current machines.

Switchgear

Compact assembly of switching and protective devices.

ERC Technical Performance Standards exclusion

Collection efficiency is NOT part of technical performance indices.

Fast-start plant

Gas-turbine station reaches load quickest from cold condition.

Device 27

IEEE function number for an undervoltage relay.

Governor (alternator control)

Prime-mover mechanism adjusted to vary active power output.

Surge impedance (Z0) of a lossless line

√(L⁄C) where L and C are inductance and capacitance per unit length.

Series reactor (short-circuit)

Limits fault current by adding inductive impedance.

Cellular-transmitter maximum power

3 watts (per Philippine regulation).

Conductor size vs. voltage raise

For same efficiency, raising voltage n-times cuts conductor area to 1⁄n².

Transformer short-circuit test

Measures copper (I²R) losses and equivalent impedance.

Transmission power capacity vs. voltage

Proportional to voltage squared (P ∝ V²).

Undervoltage relay application

Commonly protects AC motors from low-voltage conditions.

Three-phase fault impedance use

Only positive-sequence impedance considered in calculation.

RTD (Resistance Temperature Detector)

Sensor that monitors motor-winding temperature while running.

FM main disadvantage

Higher system cost and bandwidth compared with AM.

Voltage-regulation design priority

Feeder circuits require careful regulation to maintain service voltage.

Fuse-rating selection factors

Branch full-load current and fault current – NOT system impedance.

Fiber-optic principle

Total internal reflection guides light signals.

Current vs. impedance (Ohm’s law)

Current increases when circuit impedance decreases, at constant voltage.

Electron pressure build-up

Represents voltage that drives current flow.

Line-to-line fault analysis

Uses positive and negative sequence impedances only.

Required power factor at distribution connection

Not less than 0.85 (per Philippine Distribution Code).

Surge arrester selection—ignored factor

Insulation level of equipment is NOT a selection parameter (voltage & current ratings, class matter).

Full-wave rectifier output frequency

Double the AC input frequency (60 Hz input ➜ 120 Hz output).

Lead-acid cell specific gravity

Primary indicator of state-of-charge.

CCD (Charge-Coupled Device)

Light sensor used in modern fax machines and scanners.

Standard candle luminous flux

12.57 lumens (1 candela × 4π steradians).

Satellite (communications)

Spacecraft that orbits Earth synchronously to relay signals.

Local action (battery)

Internal short-circuit caused by impurities in electrolyte.

Alternator voltage vs. lagging power factor

Generated EMF must increase as power factor becomes more lagging.

Commutator hardness

Mica insulation is harder than surrounding copper segments.

Conservator (transformer)

Oil-expansion tank accommodating volume changes with temperature.

Centrifugal switch (single-phase motor)

Disconnects auxiliary winding at ~70–80 % synchronous speed.

Paper-insulated high-voltage cable

Impregnated paper serves as primary dielectric.

Series RLC resonance

Current amplitude is maximum and power factor unity at resonance.

Cable length vs. capacitance

Capacitance doubles if cable length is doubled (all else equal).

Wye-delta starter equivalent tap

Approximately 58 % line voltage during start.

DC motor traction use

Series DC motors provide high starting torque for electric trains.

Silica-gel breather

Absorbs moisture from air entering a transformer conservator.

Alternator voltage vs. leading power factor

Generated EMF decreases as load becomes more leading.

Degaussing

Process of removing unwanted magnetism from metal parts.

Synchronous motor self-starting

Not self-starting; requires auxiliary means to accelerate to near synchronous speed.

Low magnetic permeability (steel)

Reason it is hard to magnetize despite high retentivity.

Ceramic capacitor

Modern dielectric material allowing high capacitance in small package.

Copper-wire ampacity vs. diameter

Doubling diameter increases current-carrying capacity fourfold.

Diode device type

Non-linear, unidirectional semiconductor component.

Bridge rectifier output frequency

Twice the AC line frequency (same as full-wave centre-tap).

Voltage build-up limit in shunt generator

Core saturation constrains further rise in generated voltage.

Slip-ring material

Copper alloy provides good conductivity and wear resistance.

Parallel alternators essential condition

Equal terminal voltage rating for safe synchronous operation.

Short-shunt compound generator series field

Excited by load current through the series winding.

Reluctivity

Reciprocal of magnetic permeability (measure of opposition to flux).

Square-wave RMS & mean values

These values are identical for a symmetrical square wave.

Half-wave rectifier max efficiency

Theoretical limit of 40.6 %.

Ideal transformer unreal assumption

Zero leakage reactance (no magnetizing drop) not achievable in practice.