Three-phase meter "Mercury 230": feedback and connection diagram

The Mercury-230 counter is equipment that is designed to account for power and energy (reactive, active) in one / two directions in three-phase 3- or 4-wire AC systems (50 Hz) by means of measuring transformers. It has the ability to take into account tariffs for the zones of the day, losses, as well as the transmission of indications and information on energy consumption through digital interface channels.

Specifications

The meter "Mercury-230" has the following technical characteristics:

• The overall dimensions are 258х170х74 mm.
• The weight of the device is 1.5 kg.
• The time interval between verification is 120 months.
• Mean time between failures is 150,000 hours.
• The average operating period is 30 years.
• The warranty period is 36 months.

Functionality

The three-phase meter "Mercury-230" produces storage, measurement, accounting, output to the LCD and subsequent transfer via the interfaces of electric energy (reactive, active) for each tariff separately and in total for periods of time for all tariffs:

• From the moment when the readings were reset.
• At the beginning and for the current day.
• At the beginning and the previous day.
• On the beginning and for the current month.
• At the beginning and for each of the previous 11 months.
• On the beginning and for the current year.
• At the beginning and the previous year.

Accounting Parameters

The Mercury-230 counter is able to control 4 tariffs for 4 types of days in 16 time zones of the day. Monthly, this equipment is programmed in accordance with the individual tariff schedule. Within a day, the minimum period of the tariff is one minute.

Also, in power transformers and power lines, technical losses can be taken into account.

Measurement of parameters

In addition, the Mercury-230 meter can measure the following parameters in the network:

• Instantaneous values of reactive, active and total powers by the sum of phases and for each phase, indicating the direction of the vector of total power.
• Network frequencies.
• Angles between phase voltages, operating voltages and phase currents.
• Monitoring of energy and load power with transfer to a high-impedance state of the pulse output when the set points are increased.
• Power factors by the sum of phases and for each phase.

Logs of fixation

The following information remains in the journals:

• The time when the three-phase meter "Mercury-230" was switched on / off.
• Time to increase the established limits of capacity and energy.
• Time correction tariff schedule.
• Closing / opening time of the device.
• Time of occurrence / disappearance of phases 1,2,3.

Interface

The electricity meter "Mercury-230" can be presented with the following interface:

• PLC-I.
• IrDA.
• GSM.
• CAN.
• RS-485.

Information on the LCD display

The electric meter "Mercury-230" displays the following information on the LCD display:

• The current date and time.
• Network frequency.
• The power factor is a total of three phases and for each of them.
• Current and phase voltage in each phase.
• Evening and morning maximum of reactive and active power in the three previous months and in the current.
• The measured value of the total, reactive and active powers (the integration period is one second) in total for the three phases and for each with the indication of the quadrant in which the total power vector lies.
• The value of consumed reactive and active electricity in total for all tariffs and for each of them with an accrual result. The accuracy of the measurements is up to hundredths of kVAR / h and kW / h.

Direct connection

In this case, the meter is connected to an electrical line. Installation is quite simple - you just need to connect the ends of the cable from the input and output sides.

In this case, it is important not to confuse the switching of the wires:

• Terminal # 1 is input "A".
• Terminal # 2 is the output "A".
• Terminal # 3 is input "B".
• Terminal # 4 is output "B".
• Terminal # 5 is input "C".
• Terminal # 6 is the output "C".
• Terminal No. 7 is the input "zero".
• Terminal # 8 - output "zero".

During the installation, it is necessary to take into account all available limitations. Direct connection, as a rule, is used in networks with a current flow value not exceeding 100 A. Indirect calculations have shown that the installed capacity of electric energy consumers in this case should not be above 60 kW. The value of the current flowing through the meter "Mercury-230" Art, will be equal to 92 A with such a volume of consumption.

If you have a standard set of home appliances in your apartment or house - air conditioning, washing machine, TV and refrigerator - this connection scheme of the meter can justify itself. If, however, there is a heating boiler among the consumers, it is preferable to choose a different method of connection.

Semicolow connection scheme

A similar version of the connection is used when the installed power consumption of electrical energy above 60 kW. In this scheme, current transformers are used, the feature of which is that the primary winding is replaced by an electric wire.

As a result of the flow of current in the secondary winding along the conductor, according to the laws of induction, there is an electrical voltage. The indicator of this voltage is fixed by the meter. To calculate the amount of energy consumed, the conversion ratio must be multiplied by the meter reading.

To connect the meter "Mercury-230" AM in this way it is possible by various schemes, in each of which the current transformers will be used as a kind of source of information.

A ten-wire connection scheme is considered the most common. Its main advantage should be called the galvanic isolation of measuring and power circuits. The disadvantage of this type of connection is the large number of wires used.

The sequence of connection of the meter and transformers is as follows:

• Terminal # 1 is input "A".
• Terminal No. 2 is the end of the measuring coil "A".
• Terminal # 3 is output "A".
• Terminal # 4 is input "B".
• Terminal # 5 is the end of the measuring coil "B".
• Terminal # 6 is output "B".
• Terminal # 7 is input "C".
• Terminal # 8 is the end of the measuring coil "C".
• Terminal # 9 - output "C".
• Terminal No. 10 is the input of the "zero" phase.
• Terminal No. 11 is the "zero" phase on the load side.

By installing the meter to connect to the break of the transformer circuit, use special terminals, designated L1 and L2.

Another variant of connecting the meter using a semi-covarous scheme is the reduction of current transformers into a configuration reminiscent of a star. In this case, the installation of the metering device is easier, since fewer wires are required for installation, this is achieved by complicating the internal circuit. Such changes in no way affect the accuracy and quality of the testimony.

There is one more variant of connection with use of current transformers - seven-wire. To date, it has become obsolete, despite the fact that it can be found in real conditions. The main disadvantage is the absence of galvanic isolation of measuring and technological circuits. This feature makes this scheme dangerous in maintenance.

For metering devices that operate with the use of transformers, a special requirement is formulated in the regulatory documentation: between the meter and the electric wire it is necessary to install a contact pad or panel through which all the necessary connections are made.

If necessary, the secondary winding is shunted and the reference meter is connected to the measuring system. The presence of the pad greatly facilitates the installation. Equipment can be removed and replaced with another, without disabling the main power line.

Measuring transformers used in metering devices do not always have the specified parameters. After a certain time, they should be checked.

It is important to consider these details when taking readings. Semiclass connection schemes need additional attention. Sales organizations prefer to work with direct switching devices.

"Mercury-230" counter: indirect connection

Such a variant of connecting the meter is not used in the domestic sphere. The indirect scheme is designed to account for electrical energy on the tires of generating companies. These include nuclear, hydraulic and thermal power plants.

On the tires that depart from the generator, current transformers are installed. Data from the terminals of the transformers go to the meter, which records the amount of generated electrical energy. The latter through the switchgears, along the transmission lines, enters the consumers connected to the network.

Customer Reviews

The "Mercury-230" counter (the price is from 3 000 rubles) is used in the small-engine and household sector to account for the consumed amount of electric energy. This equipment is installed in rooms or enclosed cabinets, which provide additional protection against the adverse effects of environmental factors.

Consumers noted a number of positive moments that are typical for this meter:

• Compact overall dimensions.
• Small own energy consumption.
• Take out the sealing part out.

Accounting and distribution of electrical energy are complex technical tasks. Installation of electrical wiring and installation of meters must be carried out according to certain strict rules.