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» »Connection of a three-phase electric motor to a single-phase network
A 3-phase motor can be used to operate from a household AC network of one phase with a voltage of 220 volts. Alteration is possible, even if there is not much experience in electrical work with a minimum installation skill. The cost of additional circuit elements is small.
Connection of a three-phase electric motor to a single-phase network

Types of winding connections


The three-phase motor contains a stator - a fixed part with fixed wire coils. They are offset relative to each other in a circle by 120 angular degrees. The alternating current passing through the windings creates a changing magnetic field, pushing the moving part of the motor - the rotor, or, as they called it before - the armature.
There are two ways to turn on the windings among themselves:
Connection of a three-phase electric motor to a single-phase network

  • Star - the first ends of the windings are interconnected, and the phase conductors of the network are connected to the second leads of the coils.
    Connection of a three-phase electric motor to a single-phase network

  • Triangle - coils are connected sequentially one after another, the end of the third winding is connected to the beginning of the first. Schematically form a triangle, to the vertices of which the phases are connected.
    Connection of a three-phase electric motor to a single-phase network


Stages of the work:


1. Having carefully examined the electric motor, find a socket (usually an aluminum plate) with information about the parameters. No need to tackle the alteration of a motor with a power of more than 1 kW (1kW). The inscription DY 220/400 means that the motor can be turned on both according to the "triangle" (D) and the "star" (Y). The operating voltage is 220 volts single / or 400 three-phase. Terminals marked L (1 ÷ 3) for phase connection.
2. As a standard, the coils of a 3-phase electric motor are switched on by a “star”. Changing the position of the strip jumpers will create a “triangle” pattern.
3. After that, L1 is connected to the phase conductor, and on L3 - the neutral wire. We connect the middle terminal (L2) to a bias capacitor, the second terminal of which is connected to phase or zero. This determines the direction of rotation of the armature. A motor power of 100 W will require a capacitance of 8 ÷ 10 μF, for 0.25 kW a capacitor of 20 μF is needed.
4. It is convenient to quickly change the direction of rotation by switching the capacitor from the phase conductor to zero. The bipolar switch will supply power to the motor.

Connection to a single-phase network


Remove the cover of the motor junction box, gaining access to the jumpers.
Having previously unscrewed the fastening nuts, change the position of the jumpers by changing the connection diagram of the windings to a “triangle”. After that, tighten the nuts securely and replace the box cover, noting the connection wires of phases 1, 2 and 3.
Connection of a three-phase electric motor to a single-phase network

Determine the middle winding, cut the core, strip the insulation. Press the ends with the terminal lug, if any, connect the capacitor to the gap.
Connection of a three-phase electric motor to a single-phase network

Conveniently, reliably switch the circuit using terminal pairs. By connecting wires from the motor and the capacitor to the connector, ground, phase and zero are applied from the other end. Gently tightening the terminal screws will ensure reliable electrical contact.
IMPORTANT! The motor has a yellow-green conductor. It is connected to the housing. Connected through the third contacts of the cord plug and socket to ground, it protects against voltage breakdown over the mass of the motor.It is impossible to connect other wires of the electric network to it - only the yellow-green end of the power plug.
The operation of the circuit can be checked by connecting the wire from the capacitor to the phase and turning on the power 220. If all the parts are working, the motor must rotate the rotor in one direction.
Having removed the power, we switch the capacitor to the neutral conductor - the motor rotates in the opposite direction. Choosing the appropriate direction, leave the desired connection constant.
Connection of a three-phase electric motor to a single-phase network

Operational change of the side of rotation to the opposite, will provide a switch connecting the capacitor to phase or zero.
IMPORTANT! Changing direction is allowed only after turning off the power and stopping the rotor completely.

Security


Alteration of the electric motor is connected to 220 volt network operation. Careless handling, carelessness in work is associated with a threat to life or health. Do not leave connections without proper insulation. Restrict outsiders access to the installation until it is completed.

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Comments (11)
  1. Guest Victor
    #1 Guest Victor Guests February 11, 2019 18:28
    9
    “The inscription DY 220/400 means that the motor can be turned on both according to the" triangle "(D) and the" star "(Y). The operating voltage is 220 volts of one / or 400 three-phase." !!!!! Author edit this stupidity written by you !!! 220/400 - means 3-phase voltage !!! And no other way, if you have a 3-phase motor! Connection D-triangle at 220 volts of 3-phase or Y-star at 400 volts of 3-phase.
    1. Guest Vladimir
      #2 Guest Vladimir Guests February 13, 2019 10:53
      4
      Yes, everything is written correctly. Both connection and capacity calculation. The classic scheme of times when there were no frequency converters. The only drawback with this connection is that the motor power on the shaft decreases. Nowadays, whoever has "extra 10-15 thousand" buy a chastotnik with power from 1ph. 220v at the output of 3ph. 220v. and do not bother.
  2. Anatoly
    #3 Anatoly Guests February 12, 2019 3:44 p.m.
    6
    The author probably is not aware that there is a three-phase 220 v.
    1. Oksana
      #4 Oksana Guests March 26, 2019 08:56
      0
      This you do not know, three phase 220 does not exist. Three phase only 380, 660, 1020, etc. Yes, and there are three three-phase 127, but this is not with us
  3. Guest Yuri
    #5 Guest Yuri Guests February 18, 2019 12:04
    1
    The inscription 220/400 means the line voltage of the network when connecting the motor windings to a "triangle" and a "star", respectively. And not otherwise.
  4. Kiteblack
    #6 Kiteblack Guests February 22, 2019 22:00
    1
    "... An engine power of 100 W will require a capacitance of 8 ÷ 10 μF, for 0.25 kW you need a 20 μF capacitor ....: - aha - shchazzzzz! The capacity is selected individually for each engine. The lower the operating speed, the less is needed capacity. The criterion for the correct selection of the capacitor is the equality of the voltage at the phases under load. And, since the load is usually not constant, it is impossible to select the capacity exactly. Moreover, with a working capacity, even a low-speed engine will not start. In any case, you need a starting ten times higher than the working one. ..
  5. Guest Alexander
    #7 Guest Alexander Guests March 4, 2019 8:28 p.m.
    0
    The voltage of the capacitor, if it is designed to operate on alternating current (for example, MBCH), must be at least 250 V (during operation, it can exceed 250 V depending on the load).And if it is designed to work on direct current, it should be at least 400 V.
  6. Guest Alexander
    #8 Guest Alexander Guests March 5, 2019 19:28
    0
    The voltage of the capacitor, if it is designed to operate on alternating current (for example, MBCH), must be at least 250 V (during operation, it can exceed 250 V depending on the load). And if it is designed to work on direct current (for example, MBGO, K75-40), then it should be at least 400 V.
  7. Sergey Natalevich
    #9 Sergey Natalevich Visitors March 16, 2019 10:14
    0
    I offer 2 circuits for connecting a 3-phase electric motor to a single-phase network: https: //vk.com/doc387669230_491565223? Hash = 2b01762c95fac6f3b6 & dl = 2e57385317508f6ca6 https://vk.com/doc387669230_491573910ehae=f80
  8. Sergey Natalevich
    #10 Sergey Natalevich Visitors March 16, 2019 10:22
    0
    For capacitors: use K78-17 (450V 50Hz) or, as a last resort, K75-10 (250V 50Hz)
  9. Guest Alexander
    #11 Guest Alexander Guests July 26, 2019 11:31 p.m.
    0
    I look now at fact checkers and wonder if you are so smart, why don’t you publish such posts yourself, but to slander and justify anyone on the Internet ... yes, please, we will do it instantly!

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