VoltageFrequency

Voltage and frequency are two fundamental quantities in electrical systems. Voltage, the electrical potential difference between two points, is measured in volts (V) and represents the driving force that pushes electric charges. Frequency, the rate at which an alternating current completes cycles, is measured in hertz (Hz); for direct current, frequency is zero or not defined because the signal does not alternate.

In alternating current (AC) power systems, voltage is specified as a nominal value, such as 120 V or 230 V, with a frequency of 50 Hz or 60 Hz depending on the region. The actual voltage can vary with load, distance, and network conditions, and is stabilized by transformers, voltage regulators, and control devices.

Frequency refers to the speed of the AC cycle and is equally critical. Grid frequency is maintained at a fixed value (50 Hz or 60 Hz). If generation does not match load, frequency deviates. Utilities use primary and secondary control to restore frequency, drawing on reserves and automatic generation control. Large deviations can damage equipment and trigger protections.

Voltage and frequency influence devices: motors rely on frequency for speed and voltage for torque, while electronics adjust to variations. Accurate measurement and adherence to standards are essential for grid reliability and equipment safety; common instruments include voltmeters and frequency meters, and standards are set by regional and international bodies.