The construction of electrical installations, their protection and maintenance costs a lot. For the correct mutual settlement of electricity consumers, regulatory authorities are required, who monitor the correct installation and operation of three-phase and single-phase meters electricity. Violations of installation and operation are punishable by fines from the power supply organization.
Content
- Variety of devices
- Advantages and disadvantages
- Characteristics when choosing
- Connection diagram
Variety of devices
To control consumption and metering of electricity consumption, special instrumentation is used, such as electric meters. They were developed and applied back in the 19th century and since that time control and calculations for the consumed electricity have been carried out by them. The classification of devices is divided according to the type of connection, measured electricity and design features.
In accordance with the type of connection, they are:
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Direct connection. The electrical power circuit is directly connected to the terminals of the device. Usually, such meters with a power of up to 5 kW, therefore, most of the devices known to all are meters of this type.
- Transformer connection. The power circuit goes through a special measuring transformer. An indispensable condition for such connections is the obligatory load of the output terminals of the transformers. An open circuit, connection to an electric meter, is unacceptable to prevent breakdown and fire at break points.
By the type of electrical energy being measured, there are single-phase and three-phase meters. The first are control and measuring devices that keep track of energy consumption in single-phase networks with a voltage of 220 volts at a network frequency of 50 Hz. Three-phase ones keep track of three phases in networks with a voltage of 380 volts at the same frequency. Modern developments of electricity meters are able to keep track of the consumption of electricity in one phase.
According to the features of the design, electric meters are:
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Induction or electromechanical. The account is carried out due to the rotation of the aluminum disk in a magnetic field by Foucault currents. The speed of rotation is proportional to the power consumption. The number of revolutions of the disk is recorded by a mechanical counter, which is graduated in kilowatt-hours. The gearbox is set in such a way that the display of 1 kilowatt-hour is equal to 1200 revolutions of the disk. - Electrical or electronic. They convert the analog, taken from the current transformer, into a digital signal of a certain standard. The electrical circuit keeps track of and storing indicators. In modern electricity meters, programmable processor circuits are used with memory stored inside a bis microcircuit. It is very convenient for simultaneous and sequential indication of the date, time, tariff, current at the moment of time, voltage and power consumption, as well as the tariff and the calculation of the amount to be paid.
Advantages and disadvantages
The only significant disadvantage of electronic meters in comparison with induction meters is low protection against lightning discharges, which leads to their failure with loss of data. Induction appliances with a mechanical counter are free from this disadvantage. This is the reason why in many organizations, along with electronic meters, they remain for additional control. mechanical in order to avoid data loss in emergency situations, especially in the summer during thunderstorm activity.
Electronic meters have a number of advantages over induction meters. Microcircuits of electricity meters are capable of storing information that cannot be erased from the moment of its manufacture. Even after the failure of the electricity meter, you can read the data from the microcircuit and have information about the consumption of electricity at any time. Electricity meters have a higher accuracy class and record high-speed power drops, and also take into account low loads with powerful sudden surges.
In addition, they have the ability to keep track of consumption according to a multi-tariff schedule, fix the date and time of electricity consumption. Electricity meters keep track of the quality of the supplied electricity at a time. Voltage, frequency and time are recorded. Based on these data, one can judge the quality of compliance with the contract on the part of not only the consumer, but also the energy supplying organization.
Electric meters record and store data of both active power consumption and reactive power. The information is stored in the non-volatile protected memory of the device and can be displayed on a special adapter via a convenient interface. Any attempt of unauthorized access to the data of the device memory, attempt to zero or introduction into the conversion circuit additional elements are fixed by memory with date and time indication, which more effectively protects the meter from theft electricity.
It is almost impossible for a highly qualified specialist to steal by any attempts to change the connection or change the network parameters without the ability to identify this attempt. This negates the possibility of electricity theft with timely control.
Electronic meters have the ability to remotely read information, warning about attempts of unauthorized access to the device. There is a possibility of programming according to a multi-tariff plan, taking into account the time, holidays and weekends. Electricity meters are much more compact and smaller in size, allowing them to be mounted in small electrical boxes along with other mobile equipment. The service life of the electricity meters of many manufacturers is more than 30 years. Verification intervals from 10 to 16 years.
Characteristics when choosing
In order to choose the right electricity meter, it is necessary to study the characteristics and operating conditions. Three-phase and single-phase electricity meters are used respectively in single-phase and three-phase networks. Even if a three-phase meter can take into account the consumption of electricity in a single-phase network, then it is economically unprofitable to use it for such purposes.
Rated voltage in single-phase networks is 220 volts, in three-phase networks 380 volts at a frequency of 50 Hz. These are the main parameters for main consumers. There are consumer networks with voltages of 110 and 127 volts. Also, meters designed for other voltages and network frequencies, which should be noted when purchasing.
The maximum and rated load current must correspond to the sum of all currents included in the network. Also, the frequently used load must match the rating. It is undesirable to use old meters with a rated current of 5 amperes, if the frequently consumed load is much higher. Even if it is allowed to operate the meter for a long time with a load current exceeding 200% of the nominal.
Accuracy class for household electric meters is 2.0. Electricity meters with greater accuracy (the figure will be smaller) will have a much higher price, and such accuracy may not make sense for an ordinary consumer.
The number of tariffs makes sense if a multi-tariff billing system is used in action. It makes no sense to purchase an expensive multi-tariff electricity meter that requires correct software settings and is difficult to take readings if the current tariff is the same. If there is an automatic system for commercial metering of electrical energy, then it makes sense to purchase a meter with this function.
The operating temperature of the electric meter must be within the operating temperature range specified in the technical documentation. If, according to the project, the meter must be installed in electrical boxes outside, then the operating temperature range must correspond to the climatic conditions.
If in summer or winter time this range goes beyond, then the electric box is equipped with an incandescent light bulb, a heating element or a cooling fan. There are special devices with automatic or manual activation.
Connection diagram
Any connection of a single-phase electric meter must be agreed with the controlling organization, checked and accepted by their employees. The meter must be connected with four wires:
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1 terminal - connection of the input phase wire. - 2 terminal - connection of the output phase wire, goes to the circuit breaker or plug-type block. From it to the load of consumption.
- Terminal 3 - connection of the neutral wire from the electrical network (cannot be connected to the ground of the box).
- 4 terminal - connection of the neutral wire to the load (connection with the grounding wire of the box is allowed).
The phase input wires are red or brown and are designated with the letter - L. Neutral wires in blue are designated by the letter - N. Ground wires in green, yellow or yellow-green color and letters PE. The ground wire must be connected to the box body, connected to the ground loop. It must be connected to the grounding pin of each outlet.
