Voltmetry

Voltmetry is the measurement of electric potential difference, known as voltage, in electrical circuits and systems. It covers methods for determining voltage magnitude, waveform, frequency, and stability, using instruments and procedures that aim for traceability to the SI volt. The term is sometimes used to describe the discipline within electrical metrology concerned with accurately quantifying voltage in both laboratory and field settings.

Historically, voltage measurement evolved from early galvanometers and electrostatic voltmeters to modern digital instruments. The volt is named after Alessandro Volta, and modern voltmetry relies on standards maintained by national metrology institutes and international bodies to ensure consistency across devices and laboratories.

Instrumentation includes voltmeters, multimeters, and oscilloscopes. High-impedance, low-load voltmeters minimize circuit disturbance. Direct measurement is common for DC voltages, while alternating voltages require rectification or true-RMS instruments, frequency response considerations, and phase information. Differential and isolated measurements address potential differences without grounding paths that would disturb the circuit. Accommodations such as voltage dividers and attenuators extend measurement range, while calibration and traceability require regular reference measurements against standard cells or calibration rigs.

Applications span electronics manufacturing, power systems, laboratory research, and electrical installation testing. Accuracy, resolution, input impedance, temperature dependence, and EMI susceptibility are common performance considerations. Safety, insulation, and isolation are important in high-voltage contexts.

See also: voltmeter, multimeter, oscilloscope, RMS, impedance.