🧠 Viva & Glossary Prep

The ratio of energy output to total energy input over a 24-hour period, accounting for core losses that occur continuously regardless of load.

An op-amp circuit that produces an output proportional to the antilogarithm (exponential) of the input. It is the inverse function of a log amplifier.

The distorting effect of the magnetic field produced by the armature current upon the primary field flux of a machine. It can either cross-magnetize or demagnetize the main field, significantly affecting the generated terminal voltage.

A method of DC motor speed control that varies the voltage applied to the armature. It allows speed adjustment below base speed at constant torque.

A free-running oscillator circuit with no stable state that continuously switches between two output levels, generating a square wave without any external trigger.

The voltage generated by a rotating motor that opposes the applied supply voltage. It increases with speed and limits armature current during normal operation.

The rated speed of a DC motor at full armature voltage and full field current. Operation above base speed requires field weakening.

A Verilog modelling style that describes circuit function using procedural blocks (always, initial), similar in structure to software programming.

The binary configuration file downloaded to an FPGA that programs its internal logic blocks and routing interconnects to implement a specific design.

A test performed on an induction motor with the rotor locked stationary to determine series impedance parameters such as leakage reactance and rotor resistance.

A step-down DC-to-DC power converter that reduces voltage while stepping up current. It typically uses closed-loop PID control to maintain strict voltage regulation against load variations.

A square matrix connecting nodal currents to nodal voltages in power system networks. Its diagonal elements are the sum of admittances connected to a bus, while off-diagonals are the negative of admittances between buses.

An empirical equation used to characterize the resistance-temperature relationship of Platinum RTD sensors (e.g., PT100) over a wide temperature range.

A two-stage transistor configuration where a common-emitter (or common-source) stage is stacked with a common-base (or common-gate) stage to improve gain and output impedance.

A MOSFET effect where drain current increases slightly with drain-source voltage due to shortening of the effective channel length. It causes finite output resistance.

The polynomial equation derived from a circuit's differential equation whose roots determine the natural (transient) response behavior of the system.

A property of a system indicating whether it is possible to transfer the system from any initial state to any desired final state in a finite time using unconstrained control inputs.

The condition in a magnetic core where increasing magnetizing current produces little additional flux, as most magnetic domains are already aligned. It causes nonlinear behavior.

The slow, time-dependent drift in sensor output under constant applied load, caused by mechanical relaxation in the sensing element or bonding material.

A system response that returns to steady state as fast as possible without oscillating. Occurs when the damping ratio exactly equals one (ζ = 1).

A circuit that copies (mirrors) a reference current to one or more output branches, regardless of load. Widely used for biasing in analog integrated circuits.

A Verilog modelling style that describes circuit behavior using continuous assignments and logic expressions, focusing on how data flows between signals.

A three-phase winding configuration where the phases are connected end-to-end in a closed loop with no neutral point. Line voltage equals phase voltage.

A control strategy producing an output proportional to the rate of change of the error (D-action). It anticipates future errors to dampen system oscillations, reducing overshoot and settling time.

A transistor (BJT or MOSFET) configured with its output terminal connected to its control terminal, forcing it to behave like a diode. Used in current mirrors and biasing.

Power lost in a conducting core due to circulating induced currents caused by a changing magnetic flux. It is reduced by using laminated core materials.

A low-cost, low-power system-on-a-chip microcontroller with integrated Wi-Fi and Bluetooth capabilities, widely used by students and engineers for IoT applications and sensor data acquisition.

A graph showing the relationship between the terminal voltage and the load current of a generator. It illustrates the voltage drop caused by armature reaction and internal armature resistance under load.

An efficient load flow method derived from Newton-Raphson by exploiting the weak coupling between active power and voltage magnitude (P-δ), and reactive power and voltage magnitude (Q-V) in high voltage networks.

A method of DC motor speed control that varies the field excitation current. Reducing field current weakens flux and increases speed above base speed.

The electrical angle (α) measured from the zero-crossing of the voltage waveform at which a thyristor is triggered into conduction, controlling the power delivered to a load or reactor.

Field-Programmable Gate Array — an integrated circuit containing configurable logic blocks and programmable interconnects that can be reconfigured after manufacturing to implement custom digital circuits.

An electronic circuit module that produces an analog output voltage whose magnitude is linearly proportional to the frequency of an input pulse train.

A dimensionless sensitivity parameter of a strain gauge defined as the ratio of fractional resistance change to the applied mechanical strain. Typical value for metal foil gauges is ~2.

An iterative numerical method for solving nonlinear algebraic equations, such as power flow. It updates one variable at a time using the latest available values, making it simple but slow to converge.

A transducer that varies its output voltage in response to an external magnetic field. Often used in contactless speed measurement to detect passing magnets attached to a rotating shaft.

Power dissipated in a magnetic core due to the energy required to repeatedly reverse the magnetic domains during each AC cycle. It increases with frequency.

An electronic device that emits or detects infrared radiation to sense its surroundings. It is widely used in object detection and proximity sensing by measuring reflected IR light.

A control strategy that produces an output proportional to the accumulated error over time (I-action). It uniquely eliminates steady-state error but may degrade stability and increase overshoot.

A plot of the power factor versus the rotor field current of a synchronous motor operating at a constant mechanical load. It peaks at unity power factor and drops symmetrically on both the under-excited and over-excited sides.

The reactance due to magnetic flux that does not link both windings of a transformer. It is modeled as a series inductance in the transformer equivalent circuit.

The voltage measured between any two line conductors in a three-phase system. In a star system, it equals √3 times the phase voltage.

The ratio of average load to peak load over a given time period. A high load factor indicates efficient and consistent use of electrical capacity.

An op-amp circuit that produces an output voltage proportional to the logarithm of the input voltage, typically using a diode or BJT in the feedback path.

The natural logarithm of the ratio of successive amplitude peaks in an underdamped oscillation. Used to quantify the rate of decay in a damped system.

A small memory block inside an FPGA that stores precomputed output values for a logic function. It is the fundamental building block of FPGA logic cells.

A highly non-linear, open-loop unstable system where an object is suspended in the air using magnetic fields, necessitating an active feedback controller (e.g., PD control) for stabilization.

The reactive impedance in a transformer equivalent circuit that accounts for the magnetizing current needed to establish core flux, represented as a shunt element.

The maximum peak value of the response curve measured from the desired steady-state value, typically expressed as a percentage. It indicates the relative stability of the system.

The multiplication of an inverting amplifier's feedback capacitance by the voltage gain, making it appear much larger at the input. It limits high-frequency performance.

A circuit with one stable state that produces a single output pulse of fixed duration when triggered by an external signal. Also called a one-shot.

A structured description of a circuit in terms of components (gates, flip-flops) and the connections between them, generated after synthesis.

A fast-converging iterative technique for solving nonlinear equations using the Jacobian matrix of partial derivatives to update state variables simultaneously.

Any linear two-terminal network can be replaced by an equivalent circuit of a single current source (In) in parallel with a single resistance (Rn).

The residual output voltage of a Wheatstone bridge or sensor when it should ideally read zero. It represents offset error in the measurement system.

A property of a system indicating whether its internal states can be completely determined by observing its outputs over a finite time interval.

A rudimentary feedback control mechanism that switches the output completely ON or completely OFF depending on whether the process variable is below or above a setpoint, often causing oscillations (chattering).

A state encoding method where each state is represented by a separate flip-flop with only one bit active at a time. Simplifies decoding logic in FSM design.

Also called the magnetization curve, it plots the generated voltage of a generator at no load versus its field current while driven at a constant speed, revealing the magnetic saturation behavior of the machine's core.

The range of output voltages over which a current source or mirror maintains accurate, constant current output without entering an incorrect operating region.

A system response that returns to steady state slowly without oscillating. Occurs when damping exceeds the critical value (ζ > 1).

A simplified single-phase circuit model used to analyze balanced three-phase systems by considering only one phase, with the neutral as reference.

The voltage measured across a single winding or phase of a three-phase system. In a delta system, it equals the line voltage.

A vector diagram representing sinusoidal voltages and currents as rotating phasors in the complex plane. It visualizes phase relationships and magnitudes in AC circuits.

A generic control loop feedback mechanism (Proportional-Integral-Derivative) widely used in industrial control systems to continuously calculate an error value and apply a precise dynamic correction.

The change in electrical resistivity of a material when mechanical stress is applied. It is the operating principle behind strain gauges and piezoresistive pressure sensors.

A diagnostic test performed on a transformer to determine the relative instantaneous directions of induced voltage in the primary and secondary windings. It is an absolute prerequisite for safely connecting transformers in parallel or in three-phase banks.

The process of adding reactive components (typically capacitors) to a circuit to bring the power factor closer to unity. It reduces reactive power and improves system efficiency.

A right-triangle representation of the relationship between apparent power (S), real power (P), and reactive power (Q). The angle between S and P equals the phase angle of the load.

A load bus where the active (P) and reactive (Q) power are known, and the voltage magnitude and phase angle are computed during load flow analysis.

A combinational circuit that outputs the binary code of the highest-priority active input when multiple inputs are asserted simultaneously.

The time taken for a signal change at the input of a logic gate or circuit to appear at the output. It limits the maximum operating frequency of a digital system.

A control strategy that produces an output proportional to the current error value (P-action). It helps decrease rise time but cannot eliminate steady-state error completely.

A generator bus where the active power (P) and voltage magnitude (V) are specified, and the reactive power (Q) and voltage phase angle are computed.

A switching device activated by rainfall. It typically features exposed conductive traces on a PCB that act as a variable resistor when bridged by water droplets, lowering the resistance.

The time required for a system's transient response to rise from 10% to 90% (typically for overdamped systems) or 0% to 100% (for underdamped systems) of its final steady-state value.

A dangerous condition in a DC series motor where loss of load causes speed to increase uncontrollably, as the field weakens with decreasing current.

The thermoelectric phenomenon where a temperature gradient between two dissimilar electrical conductors or semiconductors produces a continuous, measurable voltage difference.

The rise in temperature of a sensor or device caused by the power dissipated by the measurement current passing through it, leading to measurement error.

The time required for a system's response curve to reach and permanently stay within a specified tolerance band (usually 2% or 5%) of the final steady-state value.

The tendency of high-frequency AC current to concentrate near the surface of a conductor, reducing the effective cross-sectional area and increasing resistance.

A reference bus in load flow studies where the voltage magnitude and phase angle are specified, and it absorbs or supplies the necessary active and reactive power to balance the system.

The difference between synchronous speed and actual rotor speed, expressed as a fraction of synchronous speed. Slip is zero at no load and increases with load.

A device that estimates the volumetric water content in soil, commonly by measuring the dielectric constant or the electrical resistance between two embedded conductive electrodes.

A technique to convert a voltage source in series with a resistor into an equivalent current source in parallel with the same resistor, or vice versa.

A type of induction motor rotor consisting of conducting bars short-circuited by end rings, resembling a squirrel cage. It is robust, low-maintenance, and self-starting.

A three-phase winding configuration where one end of each phase is connected to a common neutral point. Also called Y-connection; line voltage is √3 times phase voltage.

A mathematical model of a physical system as a set of input, output and state variables related by first-order differential equations, primarily used for modern control theory.

An active filter topology using integrators and summing amplifiers that simultaneously provides low-pass, band-pass, and high-pass outputs from the same circuit.

A third-order empirical equation that accurately models the nonlinear resistance-temperature relationship of NTC thermistors.

Also known as a back-to-back test, it determines the maximum temperature rise, efficiency, and voltage regulation of two identical transformers under simulated full-load conditions without actually dissipating the load power.

States that in a linear circuit with multiple independent sources, the response at any element equals the sum of responses caused by each source acting alone, with all others deactivated.

The characteristic impedance of a lossless transmission line, calculated as the square root of the ratio of its series inductance to shunt capacitance (Zc = √(L/C)).

The power delivered by a transmission line when terminated by its surge impedance. At this loading, the line produces exactly as much reactive power as it consumes, resulting in a flat voltage profile.

Also known as the EMF method, it is a pessimistic method used to calculate the voltage regulation of an alternator. It lumps the effects of armature resistance, leakage reactance, and armature reaction into a single synchronous impedance.

The speed of the rotating magnetic field in an AC induction machine, determined by supply frequency and number of poles: Ns = 120f / P.

The process of converting an HDL description into a gate-level netlist that can be mapped to the target hardware's logic elements.

A simulation environment written in HDL that applies input stimuli to a design under test and observes outputs to verify correct functionality.

A robust temperature sensor consisting of two dissimilar metal wires joined at one end. It produces a temperature-dependent micro-voltage across the junction due to the Seebeck effect.

Any linear two-terminal network can be replaced by an equivalent circuit of a single voltage source (Vth) in series with a single resistance (Rth).

A shunt-connected compensator consisting of a reactor in series with a bidirectional thyristor valve. Its effective reactance is varied continuously by controlling the thyristor firing angle.

A measure of how quickly a circuit responds to change. For RC circuits, τ = RC; for RL circuits, τ = L/R. After one time constant, the response reaches ~63% of its final value.

The principle used by ultrasonic and certain optical sensors to measure distance based on the exact time it takes for a propagated signal to travel to an object and reflect back.

The temporary behavior of a circuit immediately after a switching event or disturbance, before it reaches its new steady-state condition.

A technique to measure total three-phase power using only two wattmeters. The algebraic sum of both readings gives total real power regardless of load balance.

A transducer that converts electrical energy into high-frequency sound waves and vice versa. It measures distance by calculating the time-of-flight of the sound echo from an object.

A system response that oscillates with decreasing amplitude before reaching steady state. Occurs when damping is less than the critical value (ζ < 1).

A plot of the stator armature current versus the rotor field current of a synchronous motor at a constant mechanical load. It resembles the letter 'V', exhibiting minimum armature current precisely at unity power factor.

A notation describing the phase displacement and winding connection (star or delta) between primary and secondary windings of a three-phase transformer (e.g., Dyn11).

A Hardware Description Language used to model, simulate, and synthesize digital circuits. It describes hardware behavior at register-transfer or gate level.

The percentage change in output voltage from no-load to full-load conditions. A lower value indicates better voltage stability under varying load.

An electronic circuit module that generates a continuous output pulse train whose instantaneous frequency is linearly proportional to the magnitude of the input analog voltage.