Introduction To Mechanical Energy Meter
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 composed of measuring mechanism, compensation adjustment device and auxiliary components (housing, frame, terminal box, nameplate) . The following are several commonly used mechanical energy meters.
(1) Long-life electric energy meter. The service 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 jewel bearing and double jewel bearing. Double jewel bearings have lower friction and better wear resistance. The magnetic bearing mainly relies on the repulsive force between the magnets of the same polarity to suspend the rotating element in the space. As the magnetic bearing reduces the mechanical wear, the service life of the electric energy meter is prolonged. At present, most of the long-life electric energy meters that have been gradually promoted and applied use a magnetic structure 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.
(2) Wide-range electric energy meter. In recent years, due to the improvement of residents' living standards, more and more household appliances have been installed with large capacity, but the possibility of simultaneous use is small. If you choose an old-style single-range electric energy meter, the rated current is selected too large. When the actual load is very small, the operating current may be lower than 10% of the rated current of the electric energy meter and the measurement is inaccurate; on the contrary, if the rated current of the electric energy meter is selected too small, once If household appliances are used at the same time, the electric energy meter may be burnt due to overload. The wide-range electric energy meter can overcome the above problems. As long as the total current of the household appliances used is within the rated current range of the electric energy meter, it can be safely and accurately measured. Therefore, the electric energy meters installed by residents in the transformation of rural power grids and urban power grids are generally long-life, wide-range energy meters. The wide-range electric energy meter is also called the high overload multiple electric energy meter, and its overload capacity can reach 2 to 4 times. That is, the rated current of this electric energy meter is not a fixed value, but an elastic range. If the single-phase meter nameplate is marked: Class 2.0, 220V, 10 (40) A, it means that the overload capacity of the meter is 4 times; when the rated current of the electric energy meter is within 10 ~ 40A, the accuracy can still meet the requirements of class 2.0. However, the overload capacity of a 2.0-level, 220V, 10A ordinary electric energy meter is generally only 1.5 to 2 times.
