There are situations when equipment designed for 380 volts needs to be connected to a 220 V home network. Since the engine does not start, it is necessary to change some details in it. This can easily be done independently. Even though the efficiency decreases somewhat, this approach is justified.
Three phase and single phase motors
To figure out how to connect an electric motor from 380 to 220 Volts, we learn what the power supply to 380 volts means.
Three-phase motors have many advantages over single-phase household ones. Therefore, their use in industry is extensive. And the matter is not only in power, but also in efficiency. They also include starting windings and capacitors. This simplifies the design of the mechanism. For example, the fridge start-up protective relay monitors how many windings are cut. And in a three-phase motor, this element is no longer necessary.
This is achieved in three phases, during which an electromagnetic field rotates inside the stator.
Why 380 v?
When the field inside the stator rotates, the rotor moves as well. The turns do not coincide with the fifty Hertz network due to the fact that there are more windings, the number of poles is excellent, and also for various reasons, slippage occurs. These indicators are used to regulate the rotation of the motor shaft.
All three phases have a value of 220 V. However, the difference between any two of them at any time will be different from 220. This will turn out to be 380 volts. That is, the engine uses 220 V for operation, while there is a phase shift of one hundred and twenty degrees.
Because it is impossible to connect a 380 to 220 Volt electric motor directly, you have to use tricks. A capacitor is considered the easiest way. When the capacitance passes the phase, the latter changes ninety degrees. Although it does not reach one hundred and twenty, this is enough to start and operate a three-phase motor.
How to connect an electric motor from 380 to 220 V
To implement the task, you need to understand how the windings are arranged. Typically, the housing is protected by a housing, and a wiring is located underneath. After removing it, you need to study the contents. Often here you can find the connection diagram. To connect the electric motor to the 380-220 network, star switching is used. The ends of the windings are at a common point, which is called neutral. Phases are fed to the opposite side.
The "star" will have to change. For this, the motor windings must be connected in another shape - in the form of a triangle, combining them at the ends with each other.
How to connect an electric motor from 380 to 220: schemes
The diagram may look like this:
- mains voltage is applied to the third winding;
- then the voltage will pass to the first winding through the capacitor at a phase shift of ninety degrees;
- the second winding will be affected by the voltage difference.
It is clear that the phase shift will turn out at ninety and forty-five degrees. Because of this, the rotation will not work uniformly. In addition, the phase shape on the second winding will not be sinusoidal. Therefore, after connecting a three-phase electric motor to 220 volts succeeds, it will not be able to be realized without loss of power. Sometimes the shaft even sticks and stops spinning.
Working capacity
After a set of revolutions, the starting capacity will no longer be needed, since the resistance to movement will become insignificant. To discharge the capacitance, it is shortened by the resistance through which the current no longer passes. For the correct choice of working and starting capacitance, first of all, it must be taken into account that the working capacitor voltage must substantially overlap 220 volts. It should be at least 400 V. It is also necessary to pay attention to the wires so that the currents are intended for a single-phase network.
If the working capacity is too small, the shaft will stick, so the initial acceleration is used for it.
The working capacity also depends on the following factors:
- The more powerful the motor, the larger the capacitor rating will be required. If the value is 250 W, then a few tens of microfarads are enough. However, if the power is higher, then the face value can be considered hundreds. Capacitors are better to purchase film, because the electric ones will have to be further refined (they are designed for direct rather than alternating current, and can explode without alterations).
- The higher the engine speed, the higher the rating. If you take the engine at 3000 rpm and a power of 2.2 kW, then the battery will need from 200 to 250 microfarads. And this is of great importance.
This capacity also depends on the load.
Final stage
It is known that an electric motor of 380 V at 220 Volts will work better if the voltages are obtained with equal values. To do this, the winding connected to the network does not need to be touched, but the potential is measured on both others.
An asynchronous motor has its own reactance. It is necessary to determine the minimum at which it begins to rotate. After this, the rating is gradually increased until all the windings are aligned.
But when the engine spins up, it may turn out that equality is violated. This is due to a decrease in resistance. Therefore, before connecting the electric motor from 380 to 220 Volts and fixing it, it is necessary to compare the values with the unit running.
The voltage can be higher than 220 V. See to ensure a stable docking of the contacts, and there is no loss of power or overheating. Best of all, switching is done on special terminals with bolts attached. After connecting the electric motor from 380 to 220 Volts, it turned out with the necessary parameters, the casing is again put on the unit, and the wires are passed on the sides through the rubber seal.
What else can happen and how to solve problems
Often after assembly, it is found that the shaft does not rotate in the direction in which it is needed. Direction must be changed.
For this, the third winding is connected through a capacitor to the threaded terminal of the second stator winding.
It happens that due to prolonged operation over time, engine noise appears. However, this sound is of a completely different kind compared to the rumble when connected incorrectly. The vibration of the motor also happens with time. Sometimes you even have to rotate the rotor with force. This is usually caused by wear on the bearings, resulting in too large gaps and noise. Over time, this can lead to jamming, and later to damage to engine parts.
It is better not to allow this, otherwise the mechanism will become worthless. It is easier to replace the bearings with new ones. Then the electric motor will last for many more years.