An electricity meter is an integrating measuring instrument that is used to determine the amount of electricity flowing. With its help, it is possible to measure how much electricity was used by, for example, a household in a certain period of time. The value indicated by the meter is the basis for settlements with the energy supplier. The SI unit of measurement for this quantity is joule (J) - watt second. However, it is common to use kilowatt-hours (kWh) or megawatt-hours (MWh) to describe the energy consumed.
Electricity meter should be located in every house and assigned to each apartment in multi-family buildings. In the case of individual customers, the energy distributor is responsible for the installation of this type of device. He installs the equipment after technical acceptance of the electrical installation. This also means that the meter is owned by the distributor. It is the responsibility of the energy recipient to provide the device with adequate protection, e.g. against flooding or any mechanical damage.
As standard, the electricity meter is equipped with two seals. One is installed by the power company, the other by the Central Office of Measures. These elements are to prevent making any connections without the measuring device and guarantee the complete efficiency of the equipment. Breaking the seals or any maneuvering at the meter, which is supposed to lead to reading lower values than those that should actually be registered, may result in imposing high fines on the energy recipient.
The first precise electricity meter is considered to be a meter patented in 1883, which was constructed by the Berlin scientist Herman Aron. This device worked on the principle of a classic pendulum. Over time, it was replaced by the induction meter, which for many years was the most commonly used measuring device used to determine the consumed electricity. To this day, many households still use this type of equipment.
An induction electricity meter is essentially an induction machine whose aluminum disc moves under the influence of a vortex magnetic field created by two coils. In one of them, a current flows that is proportional to the current drawn by the consumer. In the second, the current is proportional to the voltage. Both coils are placed in such a way that the driving torque generated is proportional to the product of the instantaneous value of current and voltage, which in turn is balanced by the braking torque resulting from the rotation of the disc between the poles of the permanent magnet and is proportional to blade movement speed. Simply put – the counter measures each turn of the disc that corresponds to a certain amount of energy consumed.
Today, induction meters are gradually being replaced by more modern and precise meters. The biggest drawback of the older type of devices was the relatively frequent damage to the permanent magnet, which led to the misalignment of the equipment, and as a result to the device indicating incorrect values. Most often, these damages were caused by the energy consumers themselves, by attaching special magnets to the meter that inhibit the counting of subsequent units of consumed electricity.
It is now standard to install electronic electricity meters. Their operation is based on specially designed integrated circuits which, under the influence of the flowing current and the applied voltage, generate impulses in a number proportional to the electricity consumed. The value obtained in this way is appropriately converted into the energy indicated by the device.
The electronic counter is much more precise than the inductive model. It is also more difficult to manipulate its operation and falsify the actual value of the consumed current. This type of device is also usually smaller in size and easier to install in the desired location. The electronic energy meter has a simple digital display on the front. Modern models offer a number of additional functions, such as a sound signal informing about the opening of the terminal box cover. In addition, many modern counters are equipped with memory and store information about events related to device parameterization. There are even models that allow you to remotely read and regulate your energy bills in a pre-payment system.
It is also worth mentioning the so-called smart meters – they monitor consumption in real time and send information about the energy used directly to its supplier on an ongoing basis. This makes it easier to estimate future electricity bills.
The energy meter should be replaced after the validation date has passed. This period lasts eight or fifteen years, depending on the type and nominal power of the measuring device.
A new meter should also be installed if the previous one fails. If you suspect that the appliance is not working properly, report it to your energy supplier. They should inspect the meter within fourteen days. If it shows a failure, then the analysis is carried out free of charge. In other cases, you should expect a request for payment (from about PLN 50 to PLN 200).
If you suspect your meter is malfunctioning, do not attempt to repair or disassemble it yourself. Any violation of seals is connected with exposing oneself to high fines.