Electrical4U 
What is a Transformer Rating? A transformer rating is the nameplate apparent power, in VA or kVA, together with the rated voltages. Manufacturers size the windings for those voltages and for the current that follows from kVA = V × I (times √3 on a three-phase unit). Those figures are the continuous thermal duty, not … Read more
What is DOL Starter? A DOL starter (also known as a direct on line starter or across the line starter) starts a 3 phase induction motor by connecting it straight to the supply. In a DOL starter an induction motor is connected across its 3-phase supply, so the starter applies full line voltage to the … Read more
What is a Power System? An electric power system is a network of electrical components used to supply, transfer and consume electric power. Supply is generation (for example a power plant). Transfer uses a transmission line and a distribution system. Consumption includes homes (lights and air conditioning) and industry (large motors). One example is the … Read more
An electrolytic capacitor is a capacitor that uses an electrolyte to reach a high capacitance in a small volume. Aluminium types often span about 1uF to 50mF; tantalum and polymer parts use other bands. An electrolyte is a solution with a high concentration of ions. Aluminium, tantalum and niobium electrolytic capacitors are the three main … Read more
Core and Windings of Three Phase Core Type Transformer There are different types of windings used for different kinds of applications and arrangements. Windings are the conductors wrapped as helical, disc, cylindrical or crossover coils. Those turns produce ampere-turns. The core carries flux to the other winding so the two sides have different voltages. Mainly … Read more
What is Star Delta Starter A star delta starter is the most commonly used method for the starting of a 3 phase induction motor. In star delta starting an induction motor is connected in through a star connection throughout the starting period. Then once the motor reaches the required speed, the motor is connected through … Read more
There are different types of synchronous motors based on how the rotor field is produced. The two groups are non-excited rotors and current-excited rotors. Non-excited machines use steel, hysteresis material or permanent magnets. Current-excited machines use a DC field winding on the rotor. Non Excited Synchronous Motor The rotor in non-excited synchronous motors is steel … Read more
What is a Ceramic Capacitor? A ceramic capacitor is a common capacitor in an electronic circuit. Boards use it because the body is small and the dielectric is ceramic. The ceramic capacitor gets its name from its use of ceramic as a dielectric medium. Ceramic capacitors are the usual high-frequency capacitors in boards. The parts … Read more
Low power factor operation of an induction motor is the usual light-load and no-load condition. Induction Motors need magnetic fields to work, so they draw magnetizing current from the source. That current sets up flux in the air gap, often about 20% to 60% of full-load current and more on small machines. Magnetizing current does … Read more
The characteristics of a Zener diode are its forward and reverse current-voltage curves, especially the reverse knee. Ordinary diodes mainly conduct when forward biased, with a small voltage drop. In reverse they pass only a tiny current until breakdown voltage. Uncontrolled breakdown can destroy a rectifier. The Zener diode is rated to run in reverse … Read more