Electrical4U Electrical4U publishes explanations, worked examples and reference material about electrical and electronics engineering. The site is designed for students, engineers, technicians and readers who want to understand electrical principles, machines, circuits, measurement, protection and control. The library contains more than 1,000 electrical and electronics articles. Topics include electricity, power electronics, electrical and electronic symbols, alternators, … Read more
Single Phase Three Phase Power Rating VA KVA MVA Primary Voltage V KV Secondary Voltage V KV Calculate For an ideal transformer, the ratio of primary to secondary voltages equals the turns ratio: Vs = Vp * Ns / Np where For the same ideal transformer, the current ratio is the inverse of the turns … Read more
What is an Electrical Resistor? A resistor is a passive component in a circuit which provides resistance to the flow of current. There are many different types of resistors. These resistors vary in their construction, power dissipation capacities, and tolerance to various parameters (such as temperature and light). The types of resistors include: Carbon Composition … Read more
Complex Power For a sinusoidal single-phase circuit, complex power is defined with RMS phasors. The voltage and current phasors can be written as V.ejα and I.ejβ, where α and β use the same angular reference. Under the passive sign convention, complex power is the voltage phasor multiplied by the complex conjugate of the current phasor: … Read more
A simple voltaic cell, also called a galvanic cell, can use zinc and copper plates in dilute sulfuric acid. A spontaneous redox reaction creates the terminal potential difference. When a load completes the external circuit, electrons move from zinc to copper. Conventional electric current in that external circuit has the opposite direction. The copper terminal … Read more
What Is an MCB? A Miniature Circuit Breaker (MCB) is a resettable overcurrent protective device for low-voltage circuits. It opens automatically when an overload or short circuit makes current exceed its time-current characteristic. IEC 60898-1 covers certain household and similar AC breakers with rated current up to 125 A, but that limit does not define … Read more
This collection covers electrical and electronics engineering, including circuit theory, power generation and delivery, electrical machines, semiconductor devices and control. The articles range from core definitions to system analysis and practical applications.
What is a Low Power Factor Wattmeter? A low power factor meter measures power factor, while a low-power-factor wattmeter measures active power accurately when voltage and current are far out of phase. The low power factor wattmeter is a modified electrodynamometer instrument designed to retain useful torque and limit phase error under those conditions. This … Read more
A bipolar junction transistor has emitter, base and collector terminals. In a two-port circuit, one terminal serves as the reference shared by the input and output. The selected reference gives three connections: common base, common emitter and common collector. Their current gain, voltage gain and impedances differ. The surrounding bias circuit still sets the operating … Read more
Select a JFET from its current datasheet, not from a typical value alone. Each parameter needs its test voltage, current, frequency and temperature. Absolute maximum ratings are limits rather than operating targets. Common JFET parameters include: Gate Cut Off Voltage Gate-source cutoff voltage is the VGS at which drain current ID falls to a small … Read more