380 volt electrical sockets are used in factories and construction, as well as in private homes, summer cottages or car garages, to connect welding machines, motors, compressors and equipment requiring three-phase voltage. In most cases, three-phase sockets are used to supply voltage to powerful electrical equipment. In apartments, such sockets are rare, but modern manufacturers strive to produce powerful home appliances. One condition - there must be three-phase wiring in the room.
Connection basics
Connecting a three-phase socket consists in connecting 4 (without a grounding conductor) or 5 cores, three of which will be phase, the fourth - zero, and the fifth (if any) - earth. When buying an outlet, you need to imagine whether the plug on the device will fit it. If not, it is better to buy a plug (it will be possible to change it on the equipment).
Before starting work, the voltage indicator must determine where the phases, zero and ground are located on the supply cable. It is important not to confuse, since the connectionphase to the zero or ground terminal will cause damage to the equipment and electric shock to a person. Then turn off the supply voltage, make sure that it is absent using a tester.
After all the work has been done, you should turn on the power switch, make sure there is no phase on the case, measure the voltage between the phases - it should be 380 V. The socket is connected correctly if all conditions are met.
Types of three-phase connectors
380 volt sockets are: four-pin - PC 32 and five-pin - 3P + PE + N. They differ in the connection scheme and the number of sockets for the plug. The 380-volt 4-pin socket circuit is the same as that of a five-pin one, the only thing is that the ground is connected not in the connector, but directly to the electrical equipment case, and therefore it is used only for stationary equipment. Five-pin - used for relocatable installations, and a plug is connected to them, connected by a flexible copper wire.
There are also imported sockets, but they are more expensive than domestic ones. Their use is determined by the requirements of the design, or the presence of an appropriate plug in the device.
Another important difference between sockets is a certain current for which they are designed. It is necessary that this value exceed the maximum current of the connected electrical equipment.
Also, sockets of contacts 32a are divided according to the method of installation into internal and external. Internal versions are in great demand, as they are easy to use, but their installation requires additional labor costs, namely: drillingholes in the wall for the socket, fixing it with alabaster and mounting the socket in the installation box.
Socket 3P+PE+N
If you need to connect mobile electrical equipment, for example - a welding inverter, compressor, machine, it is recommended to use a 380 volt socket 5 pins 3P + PE + N. This is usually needed in workshops, car garages and construction sites. How to connect this device?
First you need to disassemble the socket to get to the screw terminals. In this case, there will be five. According to the connection diagram of the 380 volt outlet, connect one of the three phases in a free order to the terminals marked as L1, L2, L3. The phase sequence only affects how the motor will rotate - clockwise or counterclockwise. If it later turns out that the rotor is turning in the wrong direction, it will be possible to swap any two phases on the switch, or on the starter. Zero is connected to the terminal labeled N. It should be noted that there is also a zero contact on the plug, it is necessary to combine them. A conductor connected to a protective earth loop is connected to the terminal marked with PE or the earth symbol. The PE socket is located near the guide recess, which prevents the plug from being inserted into the socket by mistake.
Socket PC32a
When it is required to connect stationary equipment to electricity (always in one place),for example, an electric stove, a 380 volt 32a socket is suitable. On the three terminals of the socket L1, L2, L3 - three phases sit down, on N - a working zero. There are modifications with four contacts, but this does not mean that protective grounding is not required, it is simply connected directly to the metal part of the electrical appliance case. According to the rules of electrical safety, permanent grounding is connected to stationary equipment, bypassing the socket and cord made of a copper stranded cable without insulation (for a visual assessment of its integrity). The thickness of this cord should not be thinner than the diameter of the core of the supply wire.
Obsolete connection method
In the past, it was possible to connect the phase and neutral wires to the socket terminals in any order, and this did not adversely affect the performance of electrical equipment produced according to the TN-C system. The only thing is that this caused inconvenience to the repairmen when troubleshooting. Today, electrical equipment is produced that is sensitive to incorrect connection of phases and zero, so it is important not to make a mistake when connecting, otherwise a malfunction and emergency situation may occur.
In Soviet times, four-wire wiring was used, including three phases and zero. Fixed-type three-phase sockets were connected, which were marked with phase and zero icons (zero was signed with a ground icon) on the front and back sides. The same designations were on the fork. These four-pin plugs and sockets are still in use today, connected by the TN-C type,only with grounding and with a five-wire power cable. Where three cores will be - three phases, the fourth - zero, and the fifth - grounding.
Modern connectivity
The new TN-S earthing system obliges consumers to connect electrical equipment with a power cable with five cores, one of which will be ground (PE), and the remaining four - as before: three phases (L1, L2, L3) and zero (N). Thus, 380-volt sockets appeared with five contacts, marked in the same form on both sides of the connector housing.
Screw method of fastening cores to socket
In order to connect the cores to the connector, you need to use one of the mounting options. The screw method is time-tested and very reliable. On the reverse side of the socket there are screw clamps into which the ends of the cable are inserted and screwed to the contact. Before this, it is necessary to prepare the veins. Strip them with a sharp knife, or a special tool for carefully removing insulation - a stripper. Put on the sleeve tips and crimp them with a hand tool - a crimper. If there are no crimping pliers at hand, you can use a soldering iron and tin the twisted wires. Thus, the machined ends of the cable can already be screwed to the socket.
Screwless mounting method
This is the most modern and convenient connection because it saves the electrician's time, reduces labor costs and allows you to correct the connection error.
First the cable is stripped if required. For your information - sockets are produced where the insulationit is not necessary to remove it, it breaks through with a special sharp clip. Then the wire is placed in the socket, according to the 380 volt outlet diagram. The next step is to simultaneously press the lever and push the core under the clamp, and then you just need to release the handle to fix the wire. Then you need to check the strength of the connection by pulling the cable.
There is a modification of sockets, where instead of levers on each contact there are holes for a flat screwdriver. Then, placing the wire in the socket, you should insert a screwdriver with a flat sting into the groove, and then lift the handle of the tool up. At this point, the insulation will cut through. It remains only to remove the screwdriver and check the strength of the contact by twitching the cable.
Connection diagrams
The connection plan is different for different types of 380V sockets. Characteristics and connection also vary. The scheme of a five-pin socket has already been considered above, now it is proposed to consider in more detail the connection of 4 pins.
Types of old sockets can be quite successfully used in a modern five-wire wiring system using TN-S grounding. In this circuit, leakage current protection is provided by the PE earth wire, which is connected to the central PE earth bar. This conductor connects directly to the electrically conductive part of the equipment case, and not to the socket's grounding contact, which is not present in this case.
Naturally, a three-phase device must befixed so as not to reconnect the ground.
Voltage test
To verify the accuracy of connecting the 380 volt outlet, it is recommended to use a multimeter switched on in the AC voltage measurement mode and use the circuit.
A value of 380 V should be observed between phases in free sequence. Between zero and each phase separately - 220 volts, as well as between grounding (protective zero) and each phase - also 220 volts.
Only when all the values are the same, you can start to operate the outlet to power electrical installations. In the event of a malfunction of energy consumers, the socket will perform the function of protection against electric shock.
There is another way to protect against current leakage - this is a special device called RCD (residual current device). It is connected immediately after the power supply, and behind it is a cable to the outlet. It will turn off as soon as there is a leakage in the circuit and this will prevent electric shock to a person.
By installing a differential machine, you can replace two devices - an automatic power supply and an RCD, since it performs the functions of these elements of the electrical circuit. Usually, when only a circuit breaker is present in the wiring from the old days, specialists replace it with a differential circuit breaker and all protection issues are resolved.
Checking plug connection
If everything is clear with the question of how to connect a 380 volt outlet, then how to check the connection of the plug whenchanged her too. You should again use the multimeter, but put it in the resistance measurement mode. The plug does not need to be plugged in yet.
The resistance of the motor windings is measured through the plug contacts. In other words, the resistance between zero and each phase contact is measured. All three values must match each other and be equal to some specific number, for example R.
Next, the series resistance of the two windings is measured. Simply put, the resistance is measured between two phase contacts in any sequence. You should get three identical values, twice as large (than in the first case), that is, 2R.
If all measurements meet the requirements, then the plug is connected correctly and can be safely inserted into the outlet.
The plug and socket are designed in such a way as to ensure the normal operation of transferring the rated current of the consumer or opening the circuit, but only after the circuit breaker has been turned off. Do not use them to stop the supply of voltage, in order to avoid the occurrence of an electric arc or spark. To turn off the electrical installation, first turn off the automatic power supply, and then unplug the plug from the socket. To turn on, first plug the plug into the socket, and then turn on the machine. The same sequence must be followed even in an emergency.
