Voltmeters equipped with a change-over switch EP27 and EP29 type are destined to measure phase-to-phase and line-to-line voltages in low voltage power networks. A switch installed on the left side of the dial enables the selection of the measured voltage.
They are particularly useful for measurements in electrical machine safeguard systems.
Moving-iron meters EB16 type are destined to measure a.c. current or a.c. voltage. They measure the true RMS value of a.c. voltage or a.c. current.