Although there are many types and models of mechanical watt-hour meters (also called induction watt-hour meters), their structures are basically similar. They are all composed of measuring mechanism, compensation adjustment device and auxiliary components (housing, frame, terminal box, nameplate) . The following are several commonly used mechanical energy meters.
Long-life electric energy meter. The life of a mechanical electric energy meter in normal use mainly depends on the degree of wear of its lower bearing. Then the basic error of the electric energy meter is out of tolerance due to the wear of the lower bearing from being put into use, and the duration during this period is the life of the electric energy meter. The lower bearing of the electric energy meter has a great influence on the service life of the electric energy meter.
The bearing structures of modern electric energy meters mainly include: steel jewel bearings, graphite bearings and magnetic bearings. Gem bearing can be divided into single gem bearing and double gem bearing. Double jewel bearings have lower friction and better wear resistance. Magnetic bearings mainly rely on the repulsive force between magnets of the same polarity to suspend the rotating element in the space. The magnetic bearing reduces the mechanical wear and extends the service life of the electric energy meter. At present, most of the long-life electric energy meters that have been gradually promoted and applied use magnetic structures on the bearings.
Ordinary mechanical energy meters use single jewel bearings, and their service life is generally 5 years. The bearings of the long-life electric energy meter adopt new materials and technologies such as magnetic bearings, graphite bearings, or double jewel bearings, so that their life can be extended to about 10 years.