Electronics FAQ – Your Multilingual Guide to Electronics

  How a VFD Converts AC to DC | VFD Working Principle Explained | AC to DC Conversion in Variable Frequency Drives | Power Electronics Basics Need for AC to DC conversion in VFD:  By doing this, the VFD drive kills two birds with one stone, i.e. frequency control and voltage control. Induction motor speed control requires two major things… Frequency control Voltage control AC is converted to DC. This can be done by a single-phase or a three-phase AC input supply. E.g. arrangement of a single-phase inverter. Frequency control :  DC is inverted to variable frequency three-phase AC. To reduce harmonics,  the  PWM   technique is used to generate a sinusoidal current through the induction motor. Voltage control :  Alone, changing frequency to control the speed of the induction motor is not enough because when the speed changes, back emf also changes. At low speed, back emf is reduced, and the motor draws more current, which heats up the motor.   Voltag...

  Why a Capacitor Is Called a Non-Dissipative Element – Capacitor Energy Storage, Lossless Element, Ideal Capacitor Explained A capacitor is called a   non-dissipative element   because it   stores electrical energy in its electric field without converting it into heat   during ideal operation. Unlike resistors, which   dissipate energy as heat , capacitors   absorb energy and return it to the circuit . In real life, small losses exist due to dielectric leakage and ESR, but ideally, a capacitor is considered   lossless . Dissipation means the generation of heat: In the above circuit, power is dissipated across R1 and R2. A capacitor does not generate heat:  In the same manner, we may think that power is dissipated across C and R, but in reality, power is dissipated across R only. Why? Because a capacitor simply charges and discharges through R. In short capacitor is just absorbing and releasing charge. No current flows through the capacitor b...

  Why the Voltmeter is Connected in Parallel and the Ammeter in Series | Explained with Illustrations Measurement principle: Ideally, a measuring instrument must not alter the reading being measured. Loading effect of measuring instruments:  What does it mean? E.g. a voltmeter must not load the (voltage) source to alter the actual reading. The above circuit shows how a reading by the voltmeter is altered due to the loading effect as the input impedance of the voltmeter comes in parallel to the load. Open circuit voltage measurement:  Another example is measuring the open-circuit voltage with a voltmeter. The internal resistance of the battery or voltage source and the input impedance of the voltmeter form a voltage divider. That will decrease the actual voltage being measured. Why a voltmeter must have a high input impedance:  The input impedance of the voltmeter becomes critical for the voltage sources that have high internal impedance. For example, various process ...