Free Expert Guides on Power Systems, Circuit Design & Electrical Troubleshooting

Definition of Mutually Induced EMFDefinition: The electromotive force (EMF) induced in a coil due to the change in magnetic flux produced by a neighboring coil linked to it is termedmutually induced EMF. To understand this phenomenon, consider the following example:Take coil AB where coil B, having N2 turns, is placed in close proximity to coil A withN1turns, as illustrated in the figure below:Mutually Induced EMF ExplanationWhen switch (S) in the circuit is closed, current I1 flows through coil

Leakage Flux and Fringing Effect AnalysisDefinition: Leakage flux refers to the magnetic flux that deviates from the intended path in a magnetic circuit. This can be illustrated using a solenoid to distinguish between leakage flux and fringing effect:When current passes through a solenoid, most flux forms the main flux along the core axis, while a fraction leaks outside the coil without fully following the core path—this is leakage flux. In a long solenoid, leakage flux primarily occur

Definition of Series Magnetic CircuitDefinition: A series magnetic circuit is defined as a magnetic pathway composed of multiple sections with varying dimensions and materials, all carrying the same magnetic field. Consider a circular coil or solenoid with distinct dimensional parameters, as illustrated in the figure below:Series Magnetic Circuit AnalysisA currentIflows through a solenoid withNturns wound around one section of a circular coil, inducing a flux Φ in the core. a₁, a₂, a₃: C

Definition of Parallel Magnetic CircuitA parallel magnetic circuit is defined as a magnetic pathway with two or more branches for magnetic flux, analogous to a parallel electric circuit. Such circuits feature multiple flux paths with varying cross-sectional areas and materials, each potentially composed of different magnetic components.Parallel Magnetic Circuit AnalysisThe figure above depicts a parallel magnetic circuit, where a current-carrying coil is wound around the central limb AB. This co

Background of Transformer EMF Equation DerivationWhen a sinusoidal voltage is applied to the transformer's primary winding, an alternating flux ϕmis induced in the iron core. This sinusoidal flux links both primary and secondary windings, with its functional form described by a sine function.Mathematical Derivation of Flux Rate of ChangeThe following outlines the derivation of the transformer's EMF equation, with defined parameters: ϕm: Maximum flux (Weber) f: Supply frequency (Hz) N1: Number of

Transformer Resistance and Reactance RepresentationResistance DefinitionThe resistance of a transformer refers to the internal resistance of its primary and secondary windings, denoted as R1 andR2. Corresponding reactances are X1 andX2, withKrepresenting the transformation ratio. To simplify calculations, impedances can be referred to either winding—either primary terms referred to the secondary side or vice versa.Voltage Drops in WindingsResistive and reactive voltage drops in primary

AC Circuit FundamentalsAn AC circuit is defined as a circuit energized by an alternating power source. Alternating current (AC) is widely used for domestic and industrial applications due to its unique characteristics: unlike DC, both the magnitude and direction of current and voltage in an AC circuit vary periodically over time.AC waveforms typically follow a sinusoidal pattern, completing one cycle with equal positive and negative halves. This behavior is mathematically described as a function

Definition of Peak ValueThe peak value of an alternating quantity refers to the maximum magnitude it reaches within one cycle. Also known as the maximum value, amplitude, or crest value, this parameter for a sinusoidal quantity occurs at 90 degrees, as illustrated in the figure below. Peak values of alternating voltage and current are denoted by Em andIm, respectively.Average Value of Alternating QuantitiesThe average value of an alternating voltage or current is defined as the mean of all insta

Star Connection in Three-Phase SystemsIn a star (Y) connection, the similar ends (either starts or finishes) of the three windings are joined at a common point called the star or neutral point. The three line conductors extend from the remaining free terminals to form the phase connections.For a three-phase, three-wire system, only the three line conductors are connected to the external circuit. Alternatively, a four-wire system includes a neutral conductor drawn from the star point, as illustra

Plugging (Reverse Current Braking) in DC MotorsIn plugging (reverse current braking), the armature terminals or supply polarity of a separately excited or shunt motor is reversed while the motor is running. This causes the supply voltageV and the induced back EMFEb to act in the same direction. Consequently, the effective voltage across the armature during plugging becomesV + Eb—nearly double the supply voltage—reversing the armature current and generating high braking torque