Introduction To Mechanical Energy Meters
Although there are many types and models of mechanical energy meters (also called inductive energy meters), their structures are basically similar, and they are all composed of measuring mechanisms, compensation adjustment devices and auxiliary parts (shells, racks, end button boxes, nameplates). The following are several commonly used mechanical energy meters.
(1) Long-life electric energy meter. The life of a mechanical energy meter in normal use mainly depends on the degree of wear of its lower bearing. Then from the time it is put into use to the time when the basic error of the electric energy meter is out of tolerance due to the wear of the lower bearing, the duration of the 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 structure of modern electric energy meter mainly includes: steel jewelry stone bearing, graphite bearing and magnetic bearing. Gem bearing can be divided into single gem bearing and double gem bearing. Double gem bearings have less 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 space. Magnetic bearings extend the life of the energy meter by reducing mechanical wear. At present, the long-life electric energy meter that is gradually popularized and applied mostly adopts a magnetic structure on the bearing.
Ordinary mechanical energy meters use single gem bearings, and the service life is generally 5 years. The bearing of the long-life electric energy meter can be extended to about 10 years due to the use of new materials and technologies such as magnetic bearings, graphite bearings or double gemstone bearings.
(2) Wide range electric energy meter. In recent years, due to the improvement of residents' living standards, more and more household appliances are installed with large capacity, but the possibility of using them at the same time is small. If the old single-range electric energy meter is selected, the rated current is too large. When the actual load is very small, the running current may be lower than 10% of the rated current of the electric energy meter, which makes the measurement inaccurate; on the contrary, if the rated current of the electric energy meter is selected too small, once When household appliances are used at the same time, the electric energy meter may burn out 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 measured safely and accurately. Therefore, the electric energy meters installed by residents in the reconstruction of rural power grids and urban power grids are generally long-life and wide-ranging electric 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 nameplate of a single-phase meter is marked with: 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 energy meter is within 10-40A, the accuracy can still meet the requirements of Class 2.0 . And 2.0 class, 220V, 10A ordinary electric energy meter, its overload capacity is generally only 1.5 to 2 times.
