Registered Electrical Engineer - Supply & Distribution (China) - independent technical foundations flashcards

30 cards. Read the term and the definition here. The deck at the top of this page is optional.

Phasor

A complex representation of a sinusoidal quantity at one frequency with a stated magnitude and phase convention.

Impedance

The complex voltage-to-current relationship in a specified sinusoidal model, combining resistance and reactance with consistent units.

Admittance

The reciprocal of impedance for the stated circuit model, useful when combining compatible parallel electrical branches.

Complex power

A quantity formed from RMS voltage and the conjugate current, with real and imaginary components under a specified convention.

Displacement factor

The cosine of the relevant fundamental voltage-current phase angle, distinct from total power factor in a distorted-waveform system.

Per-unit base

A consistent reference power and voltage set used to normalize network quantities before combining equipment data.

Prospective fault current

The current predicted at a specified fault location under the modeled source and network conditions, distinct from normal load current.

Breaking capacity

A specified device duty related to interruption of fault current under defined conditions, not simply its continuous current rating.

Selectivity

Coordination intended to isolate the affected part of a system while limiting unnecessary operation of other protective devices.

Current-transformer burden

The secondary circuit load presented to a current transformer, which affects the performance of the specified measurement or protection system.

Residual current

An imbalance measured in a defined set of circuit conductors, interpreted according to the device arrangement and intended protective function.

Voltage regulation

A description of voltage change between stated operating conditions, requiring an explicit reference value and equipment model.

Slip

The difference between synchronous and rotor speed relative to synchronous speed for an induction-motor model with a stated sign convention.

Commissioning evidence

Recorded inspection, measurement and functional-test results supporting a defined installed-system requirement, including relevant limitations and unresolved defects.

Humidity ratio

The mass of water vapor relative to dry-air mass in a moist-air model, distinct from relative humidity.

Sensible heat factor

The ratio of sensible load to total load under the specified definition, useful for separating temperature and moisture effects.

Pump head

Energy added or required per unit weight of fluid, interpreted with the actual static, pressure and friction conditions.

Illuminance

Luminous flux received per unit area, measured in lux and distinguished from lamp output, surface luminance and electrical power.

Cause-and-effect matrix

A documented relationship between specified inputs, conditions and required system responses, used for design and commissioning of coordinated functions.

Measurement boundary

The explicitly defined physical or accounting extent of a measured quantity, needed to distinguish energy, demand and component or system performance.

System boundary

The chosen separation between a modeled system and its surroundings, determining which flows and interactions count as inputs or outputs.

Assumption

A stated simplification or condition used to make reasoning possible, which limits where the result can legitimately be applied.

Dimensional consistency

Agreement of physical dimensions across an equation, a necessary check that does not alone establish the correctness of its model.

Sign convention

A declared rule assigning positive directions or senses, required for consistent forces, moments, voltages, currents and coordinate calculations.

Free-body diagram

A representation of an isolated body with its external interactions, used to formulate the relevant equilibrium or motion equations.

Schematic

A functional representation of connections or relationships that need not reproduce the physical layout, scale or operating authorization of equipment.

Tolerance

A specified allowable range or deviation for a characteristic, distinguished from measurement uncertainty and from statistical process control limits.

Resolution

The smallest distinguishable display increment or input change under the device’s specified convention, which is not itself an accuracy guarantee.

Calibration

An established relationship between instrument indications and reference values under stated conditions, with associated uncertainty and traceability.

Repeatability

The closeness of repeated results under specified similar conditions, which does not by itself demonstrate freedom from systematic bias.