Three-phase power sockets with grounding contact

A three-phase outlet is designed to connect consumers of electrical energy to a network voltage of 380 volts. It should be noted that three-phase sockets are also actively used to connect powerful single-phase consumers, for example, stoves or hobs. Most of these electrical appliances are capable of operating at a voltage of 380 or 220 volts, with a three-phase connector being used in both cases. The difference is only in the connection diagram.

Design

Since the connection of consumers to the network voltage of 380 volts involves the use of three phase wires (L1, L2, L3), as well as zero (N) and protective (PE) wire, the design of the three-phase connector is significantly different from bipolar devices designed to connect single-phase consumers.

It should be noted that the terms “three-phase” and “three-pole” are not synonymous. Each pole of the device represents an independent path of electric current. Therefore, an ordinary bipolar 220V socket, equipped with a grounding contact, is a three-pole.

The main components of a power outlet, designed for a voltage of 380 volts, are:

1. The base of the body.
2. Protective cover.
3. Mechanism.
4. Sealing ring.

Currently, three-phase electrical connectors are used with four or five contacts of a needle or knife type. The choice of one or another model of such equipment is carried out based on the characteristics of the connected consumer.

To connect three-phase electric motors to the 380V network, as well as other symmetrical loads, a three-wire wire can be used. To connect consumers that create an unbalanced load, a five-pin outlet is used, equipped with a zero and ground contact.

There are also 380 volt devices with 7 connectors (each phase has its own zero, as well as a common grounding conductor), such devices are used in rooms where it is necessary to ensure a very high level electrical safety.

Minor changes in the design of three-phase outlets can be made based on their power, purpose, as well as the degree of protection against dust and moisture. There are sockets with protective curtains, inclined to 380 volts, devices equipped with a plug, flat, waterproof, etc.

Installation procedure

The basic rules that must be followed when installing such a device remain the same as when installing a bipolar outlet designed to operate on a 220-volt network.

The procedure for this may be as follows:

• Before performing any work in the electrical wiring, disconnect the voltage at the input electrical panel.
• To connect suitable wires from a 380V network to a power outlet, it must be disassembled. To do this, unscrew the bolts located on the front of the product body and remove its cover.
• The base is fixed to the wall. In order to achieve an even arrangement of the device case, a building level should be used. The mounting method depends on the material of the wall on which the socket is installed.
• The institution of the power supply cable to the base of the device is being implemented. In the case of open laying of such a cable, it must be enclosed in a corrugated tube. For concealed installation, you must first perform wall chasing. Any work with elements of the electric network voltage of 380 volts can be carried out only with the power off. Before inserting the cable into the outlet, a sealing ring is put on the corrugated tube, which is inserted into the corresponding grooves located on the base of the case.
• Insulation is removed from each core of the power cable at a distance of 10 mm from its end.
• The connection of the wires of the power cable to the terminals of the outlet is performed. For some consumers of electricity, an important condition for normal operation is to observe the correct phase sequence. This means that you should carefully monitor the correct connection of the phase wires to the contacts of the outlet. The insulation of the protective earth conductor is yellow with a green stripe. Most models of three-phase outlets have a marking on their case, which allows you to unambiguously determine which connector you want to connect a particular wire to. Phases are indicated by the symbols L1 (white color of the insulation of the wire), L2 (black or black and white), L3 (blue).

Advice! If the motor is connected incorrectly at the moment of voltage supply, it will start to rotate in the opposite direction. To eliminate this malfunction, it is enough to swap two adjacent phases in the outlet.

• A protective cover is installed.
• It checks the correct functioning of the device by connecting a consumer to it and applying voltage.

Three-phase outlet selection

Before buying a 380V outlet, you should clearly determine what technical and operational characteristics it should correspond to.

The main parameters of 380 volt devices are:

• Rated current. The value of this parameter is determined based on the total power of consumers connected to the device. Standard values ​​of rated currents for 380V sockets are: 16, 32, and also 64 A.

Important! When connecting three-phase consumers of the same power to the 380V network according to the "star" or "triangle" scheme, the currents flowing through them will be different. This should be considered when choosing an outlet, as well as the cross-section of the connecting wires.

• The phase current flowing in the electric circuit when the consumer is connected to the 380V network according to the "star" scheme (the most common connection method) is:

where cosφ is the power factor determined by the properties of the consumer.

• Number and type of contacts. Today, many consumers connected to a 380-volt three-phase network are supplied without an electrical plug. However, in some cases, it is necessary to select a socket for an existing plug.
• Degree of protection of the device case from dust and moisture (IP). This parameter is extremely important for products installed outdoors or in rooms with high humidity. In these cases, it is best to use devices that have a degree of protection of at least IP44.
• To connect portable electrical equipment, attention should be paid to three-phase cable sockets in a mobile version.

Installing a three-phase outlet in a 380V network is not too different from installing a single-phase two-pole device and can be performed even by a lay person. However, to ensure proper operation of consumers, you should pay increased attention to the wiring diagram in these devices. In addition, any work on the installation or repair of electrical equipment should only be carried out with the power off. The voltage of 380V is life-threatening, therefore, before performing any action with the wiring elements, be sure to verify its absence.