Motor connectionSuppose that there is an electric motor for 380 V, but it was necessary to connect it to one phase. Given that the user is not an electrician, for him this procedure will seem very difficult. But this article can help in this matter by providing some necessary information on this topic.

How to connect the engine 380 V to 380 V, it will be possible to find out below. There should be no difficulties with this. But with the connection of a three-phase motor to one phase, questions may arise. Therefore, this procedure will be described first.

Before you make a connection, you should remember the fact that you should not expect full working power from a three-phase electric motor operating on one phase. A three-phase motor may well work on single-phase support, but its power will equal in the best case. 70% of his real possible power. In addition, there will be problems with the selection of working capacity at a constantly changing load.


  • 1 How to connect the engine 380 to 380
  • 2 380 V motor connection
    • 2.1 Star-delta scheme
  • 3 How to connect a 380 V to 220 V electric motor
    • 3.1 Wiring diagram
  • 4 findings

How to connect the engine 380 to 380

Instrumentsthat will be needed during the connection process:

  • soldering iron
  • arrow voltmeter
  • screwdriver

Materials used in the work:

  • electric motor 380
  • working capacitors
  • starting capacitor
  • 220 V start button
  • tin
  • acid or rosin
  • insulating tape

380 V motor connection

You can connect a three-phase motor to a single-phase network, using the star-delta scheme.

Star-delta scheme

Motor connection according to the schemeIn many domestic electric motors, the star circuit has already been assembled, which in this case involves only the realization of a triangle. This implies the connection of three phases and the formation of a star from the remaining six ends of the winding.

Star triangle has a very important advantage. The fact is that when using this circuit, the electric motor realizes its maximum power in operation. The main disadvantage of such a scheme is its complexity. Most often, this scheme is used by amateur masters.

To meet such a scheme somewhere in production is very problematic, since it is rarely found in such conditions. This circumstance is explained by the fact that, due to the complexity of the scheme, it is very difficult, and senseless, to organize such a laborious connection.

The difference of individual schemes star and triangle is that in the first case six connection terminals are used, while in the second - three. If you take into account the characteristics, then you can see the fact that the engines with a star are much quieter. But this plus can be blocked by a significant minus of electric motors operating with such a connection. The minus is the reduced power of work when connected to a single-phase network - about 50% of the nominal. An electric motor connected to a single-phase network using a triangle circuit works louder, but the power is significantly higher and amounts to approximately 70% of the nominal one.

The video below describes the principle of connecting a three-phase electric motor using a delta circuit.

How to connect a 380 V to 220 V electric motor

How to connect the motor correctlyFirst, before connecting, you should decide on capacitors. In the named connection, two types of them are used at once:

  1. Launchers
  2. Workers

The first type of capacitor will be used to start the engine. And just for that. When the engine picks up the required number of revolutions, the starting capacitors are excluded from the electrical circuit. If this does not happen, it will lead to serious consequences. In other words, it will entail that the engine will simply burn as a result of current skew in the two windings of the electric motor.

The main work is designed for working capacitors. In order for the capacitor to work properly and for a long time, you should follow three very important rules that will help ensure efficient operation working capacitors:

  1. All working capacitors should be connected to each other only in parallel.
  2. The total capacity of the working capacitor should be determined by the special relation: per 100 W of power of the electric motor 7 microfarads of the working capacitor.
  3. The rated voltage of each capacitor is at least 300 volts.
  4. Following these rules, it is possible to significantly extend the work of working capacitors and not only them. The operation and durability of the engine also depends on the operation and operation of the capacitors when they are included in the electrical circuit. In the best case, the engine will stop working within one process or it will not start at all if the connection is incorrect. In the worst case, the electric motor will burn and the user will have to wrestle with how to make up for the loss.

It is very important to know that the capacity of the starting capacitors must necessarily be three times larger than the capacity of the working capacitors.

It should be borne in mind that the calculation of the capacitance of the capacitors is performed at nominal power, therefore, if the engine will work underloaded, then he will warm up and you need to reduce the capacity of the working capacitor in order to reduce the current in the winding.

If the capacity is less than required, the power that the electric motor will develop will be low.

It should be remembered that capacitors even after switching off retain dangerous voltage at their terminals. To avoid accidental contact, you should always make fences around capacitors. It is recommended to always discharge the capacitor before you start working with them.

We must not forget that the connection is three-phase 3 kW motor home to standard wiring is strictly prohibited. Such a connection will lead to knocking out traffic jams and machines. It will also be possible to melt the insulation on older wires or in cases with incorrectly selected current protection.

Wiring diagram

  1. Engine wiring diagramFirst you need to connect the capacitors. As mentioned above, this should be done by connecting them in parallel. This is a very important point.
  2. Then you need to connect a bunch of capacitors with two wires to the motor and to the AC network.
  3. In the third stage, you should simply turn on the engine. This must be done in order to start to check whether it is spinning in that direction. If that is required, then no further action is required. Connection made. Otherwise, you should perform simple manipulations with the wires, namely, you should swap the wires of the connection to the winding.

For a more clear and illustrative explanation of the entire connection process below read the attached video. This detailed video instruction will help to understand the whole process and in all moments that are incomprehensible to the reader:


Connecting a three-phase electric motor to both a single-phase network and a three-phase network is not difficult in principle, especially if there is a large number of schemes, instructions and videos on this topic.

One of the main points in the implementation of connecting the engine to the power supply network is to comply with safety measures. It should always be remembered that all manipulations with the networks through which the current flows are already a certain risk. So you should avoid all contact with the elements that are energized.

If there are some concerns and doubts about the implementation of the whole procedure, but there is no experience, should consult with a professional in order to avoid equipment breakage and physical injuries, since it is better not to risk your health.