Amometers

An amometer, more commonly ammeter, is an instrument used to measure electric current in amperes. Amometers are designed to present minimal resistance in the circuit; they are connected in series with the load so the same current flows through both. To measure high currents with low internal resistance, many amometers use a shunt—a precision low-resistance element that carries most of the current while the meter movement reads the voltage drop across it.

DC and AC variants. DC amometers typically use a moving-coil galvanometer with a multiplying resistor. AC amometers historically used moving-iron or electrodynamic movements; modern instruments often are digital true-RMS meters or use current transformers and shunts.

Types include moving-coil (galvanometer) for DC; moving-iron for AC; shunt-based meters; clamp-on amometers measuring current with a magnetic core around the conductor; digital amometers that display numerically; true RMS meters for accurate AC current measurement.

Performance. Accuracy is expressed as a percentage of full-scale deflection (class). Range selection can be manual or automatic. Burden voltage (voltage drop across the meter) should be minimized for most circuits, especially low- voltage or high-precision work. Calibration is required to maintain accuracy.

Applications. Amometers are used in electrical laboratories, power distribution, automotive, electronics manufacturing, and maintenance to monitor and verify current levels in circuits and devices.