Single Phase Meters
Single phase meters are commonly rated for 240 V AC supply; the current ratings are 5/10, 10/20, 2.5/10 or 5/20 A or are for direct connection to the mains. They begin registration along with small load of about 6 W and record up to 4800 W. The major feature of a single-phase meter (electromechanical induction type) is its simplicity, compactness and robust design. It comprises a potential coil and a current coil. The potential coil is fitted on the center limb of an E shaped electro-magnet and linked across the supply mains.
Same, the current coil consisting of a few turns of heavy gauge copper wire is wound on two limbs of a U shaped electro-magnet. The two fluxes, produced through the voltage (pressure or potential) coil and current coil, set up a mechanical torque on the non-magnetic aluminium disc (that is located among the 2 coils) causing it to rotate. A brake magnet of C shaped alloy steel is given to control the movement or rotation of the disc set up through two fluxes. The disc rotates through the narrow air gap of the C shaped magnet and eddy currents are set up, that interacts along with the field and exerts braking effect.