In three-phase power supply systems, plugs and sockets are used that differ from household ones. Electric boilers and especially powerful machines are also being developed for three-phase voltage. To supply electricity according to the "delta" scheme, 4 wires are used - three phases (A, B, C) and protective earth (PE).
Content
- Features and types of three-phase sockets
- Connecting a three-phase socket and plug
In the case of a "star" circuit, a neutral or neutral wire is added - N. To enhance protection against electric shock, each phase connector is equipped with neutral conductors, along with a grounding conductor. The standards for the color coding of three-phase wiring are as follows: black, red and brown are used for the phases, for grounding - green with a yellow stripe, and for neutral - blue.
Features and types of three-phase sockets
Each manufacturer produces its own plug and socket options. Therefore, these elements must be purchased at the same time, otherwise parts from different manufacturers will not fit together.
There are two types of three-phase electrical connectors for sale:-
Power connectors RSh-VSh in black carbolite housings are used to connect industrial and household three-phase equipment, for example, electric stoves. Rated current - 25-30 amperes. Contact parts are flat, cylindrical or combined. Screw cable clamps are used to connect the wires. Thanks to the clamps, the connection becomes reliable. The sockets are protected from children by special curtains. Cost - from 100 rubles. - Power connectors SSI 125 manufactured by IEK are designed for a rated current of 32 amperes and have an IP 44 protection class. This allows the use of three-phase sockets in high humidity. They are attached to the wall with dowels. The wires are connected with clamping screws. This is not the most reliable option. It is recommended to use a connection with a ferrule and a pressure plate.
Connecting a three-phase socket and plug
In single-phase household outlets two wires are used - phase and zero (neutral). 3-phase are connected with four wires, the diameter of which must be at least 2.5 mm. If the load exceeds 10 kW, then the diameter of the wires of the power cable must be at least 6 mm. A three-pole circuit breaker is placed in front of the outlet for a tripping current of 40 amperes. And to protect against current leakage, residual current devices - RCDs are used.
Turn off the power supply before connecting the power connectors. Phases A, B and C are connected to contacts L 1, L 2 and L 3, respectively. The connection procedure determines in which direction the rotor of a three-phase motor will rotate. It is necessary to open the socket, insert the cable, and connect the wires to the corresponding terminals as securely as possible: black (L 1) - to A, red (L 2) - to B, and brown (L 3) - to terminal C. The neutral wire is connected to the N pin and the ground to P. E. The correctness of the connections is checked with a probe.
Then fasten the cable inside the socket. For stationary equipment, continuous grounding is required, which is laid with a green-yellow stranded copper wire. The cross section should be the same or slightly larger than that of the main cable. There must be no disconnecting devices in the circuit. Grounding helps to avoid dangerous electric shock if insulation breaks inside the unit. Wall socket should be securely fixed to the surface with dowels or screws.
To connect, disassemble the plug, insert the cable coming from the device into the housing, and attach the wires to the pins. Then fix the cable in the plug housing and assemble it.
The 380 volt socket is connected to a three-phase network through an automatic machine and residual current devices. Electrical safety rules prohibit the installation of switching devices in the neutral and grounding circuit. Each phase has its own RCD, so three of these devices will be needed. The pickup current should be 30 milliamperes. A lower value will cause false alarms, and a higher current will not provide sufficient leakage protection. Residual current devices are connected strictly between the machine and the outlet.
Remember the electrical safety rules. All work must be carried out when the voltage supply is disconnected. At 380 volts there is an increased risk of electric shock.
