Three phase meter: connection and operation
In houses, apartments, garages, as a rule, a single-phase power supply of 220 volts is provided. Each electric meter has an input and output phase with zero. However, sometimes there is a need to connect a three-phase meter, when electrical devices consume more than 10 kW of power - various machines, electric welding, etc.
Three Phase Power Benefits
- There are many electrical home appliances that only function from 380 V.
- Excessive load on a single-phase input can serve as a basis for voltage drops for your house or apartment, as well as for your neighbors. This, in turn, can reduce the service life of household appliances.
- There is no need to install a cable or wire of large cross section. After all, according to Ohm's law, with the same load of 380 volts, a large electrical power is supplied.
- Provided that the three-phase and single-phase electric motor will consume the same energy, the mechanical power of the latter will be much less.
Three-phase electricity meter can be direct and indirect inclusion. In the latter case, the connection is made through a current transformer. Indirect inclusion is used to account for electricity at high loads. Live connection is used in simple houses and garages, since in these rooms the load does not exceed 100 A, and the maximum power is not more than 60 kW.
The connection of the three-phase meter is carried out in a special electrical panel with a platform designed for fastening 3 screws.
A five-conductor cable consisting of three phases, a ground conductor and a zero is inserted into the electrical panel. Phase “A” is connected to the first contact, to the third contact - “B”, to the fifth one - “C”.
From the meter with the contacts 2, 4, and 6 phases go to the machines to electrical consumers. Zero comes to the seventh contact and comes out of the eighth. The ground wire is connected to the grounding bar of the electrical panel.
The old three-phase induction meter is connected in a different way. A jumper is installed on 1 and 2 contacts, the phase is connected to the first contact and from 3 contacts it goes to the load.The same should be done with the remaining phases, connected by jumpers on pins 4-5 and 7-8. Phase enters at pins 4 and 7 and exits pins 6 and 9. Then the zeros are connected.
The new three-phase meter can be connected to the data network in the control room. Connection to the low-current network is carried out through special contacts.
A more detailed wiring diagram can be found in the technical data sheet attached to the device or on the back of the contact cover.
To install a three-phase meter, you must write a statement to the company engaged in the supply of electricity. Connect this metering device to a qualified technician. This is not only a requirement of organizations supplying electrical energy, but also a safety standard. Unprofessional installation of the counter will cost a lot not only to the owner of housing, but also to the master himself.
The three-phase meter is installed in the place where the wiring passes. All the wires passing through the apartment are connected to the input terminals. The output terminals play the role of an electrical flow separator.
It is necessary to install a metering device only in places easily accessible for servicing, in special cabinets, on boards, panels, that is, on a rigid basis. In accordance with current regulations, the meter panel must be installed at a height of at least 1.3 m and at most 1.7 m.
After the three-phase electricity meter is installed, it should be sealed. This procedure is performed by a specialist organization that is engaged in the supply of electricity. After sealing, you can proceed to the installation of electrical wiring.
If a three-phase meter (price on average from 2,900 rubles) is installed where there is a danger of contamination or in a place accessible to unauthorized persons, then it is preferable to install it in a special cabinet. This cabinet at the level of the dial has a window and is locked with a key.
The presence of rations and twists in the wiring to the metering device is not allowed. The minimum wire size should be at least 2.5 mm2Aluminum wires not less than 4 mm2. During the installation process, near the metering devices it is necessary to leave the ends of the wires at least 120 mm.In rooms with a voltage of less than 380 volts, it is necessary to provide for switching off the device with a special switching device at a distance of 10 meters from the meter.
When installing the meter, it is important to ensure a strong and reliable contact of the connected wires. Tighten the terminal screws in 2 steps. When using a copper flexible wire it is recommended to perform tinning with solder in advance. It is advisable to use tin-lead solder, which will provide a more reliable grip. After six months of operation, it is recommended to call a specialist of the company engaged in the supply of electricity to check the contacts in the terminal row.
Installation and operation
- The inclusion of a three-phase meter should be made in accordance with the EMP (Rules for electrical installations).
- Operation is carried out taking into account the "Rules of technical operation of electrical installations of consumers" TKP 181-2009.
- It is necessary to turn on the metering device in accordance with its scheme and nominal data, which are located on the inside of the clamping block.
- Installation, dismantle, checking, repair,Opening and branding should be carried out only by authorized organizations and persons, in accordance with applicable regulations and in compliance with the sequence of phases.
- The three-phase meter (price depends on the manufacturer) takes into account electrical energy in kW / h.
- Transformation ratios that are not taken into account by the device are indicated on the additional panel mounted on the terminal block cover. On the primary winding of the transformer, the energy value in this case is determined by multiplying the instrument reading and the coefficient K.
- The metering window, in which the tenths of kWh / h are indicated, is separated by a comma and bordered with black. In counters 10-40A and 50-100A there are no shares of kW / h.
- The three-phase meter "Mercury" or any other device must pass a state calibration according to STB 8003-93 every 4 years without fail.
- Verification is carried out in accordance with GOST 8.259-2004.
- The presence on the metering device is not evidence of its operation, it is just the result of the calibration of the device at the factory.