Connection and testing of single-phase electric motor

Single phase motors are used for various household appliances. They are in the pumps, washing machines. With your own hands, if necessary, you can repair and connect such a unit, check its winding. To connect a single-phase electric motor, you must select a circuit, and then follow the process exactly.

General view of single-phase starting device

General view of the single-phase starting device.

What is a single phase motor? In this case, the current creates a magnetic pulsating field with a different amplitude. It is this that when the engine starts, the resultant moment is equal to zero; without a special device, it simply does not begin to rotate. If the rotor is set in one direction or another (that is, its rotation is observed), then one moment begins to prevail over the other, the motor shaft continues to move.

The motor is started due to the appearance of a magnetic rotating field. The number of windings is two, the rotor is used short-circuited. Basically, single-phase motors are used for low-power devices, for example, for home appliances, for fans, pumps, and for drilling wells for water wells.

How to connect the ACI 80 C2 electric motor with your own hands

Connection diagrams of single-phase electric motor

Wiring diagrams for single-phase electric motor.

For example, a single-phase ACA 80 C2 motor connection is required. Let him have the following technical specifications:

  • rotational speed is 3000 rpm;
  • motor power is 2.2 kW;
  • The efficiency (efficiency) of this motor is 76%;
  • operation mode - S1;
  • cosφ = 0.9;
  • construction protection degree - IP54;
  • the motor can work in a network of 220 V;
  • for a working capacitor, the voltage is 450 V;
  • the capacitance of the working capacitor used is 50 μF.

Such a single-phase motor is usually used for small-sized machines that can be used in everyday life. A connection to the 220 V network is required. The installation parameters are indicated in the engine passport, they need to be paid attention to, since they set the conditions of use.

The connection of a single-phase electric motor is carried out in the following way:

Single phase motor connection

Connecting a single-phase motor.

  1. The motor design consists of 2 windings, which are shifted relative to each other strictly by 90 °. Start (auxiliary) is denoted Z1, Z2, the working winding - U1, U2. The main winding is connected to a single-phase network, the starting one - through the provided working capacitor. It is important not to be mistaken at this stage, for the single-phase asynchronous motor it is necessary to disconnect the auxiliary winding immediately after the start. In this type of motor, such a winding should always be energized, i.e. Do not turn it off. This is required for the reason that the engine has a rotating type of magnetomotive force.
  2. The capacitance of the capacitor is 50 microfarads, it is indicated in the passport of the motor. Of course, it is possible to calculate the capacity independently, but a complex formula is used for this, and considerable experience is required in such calculations, therefore it is better to pay attention to the indicated technical characteristics at once.
  3. Next, it is necessary to connect the starting capacitor parallel to the working capacitor, its capacity is determined only by experience by obtaining the highest value of the starting torque. It is optimal to take a capacity of approximately 2-3 times greater than the capacity of the worker.
  4. The start capacitor is connected using a time relay, although such a circuit may seem complicated. But it is more reliable, different quality. It is allowed to use a simpler scheme, for example, using a conventional start button.

For a single-phase motor, short-circuited rotors are used. Next you should pay attention to the terminal block, which has 6 pins. To perform a direct connection, a voltage supply of 220 V is applied, it is applied to terminals V1 and W2. Jumpers are placed between terminals V1-U2, U1-W2.

If a reverse connection is required, then it is necessary to apply alternating voltage of 220 V to the same terminals that were used earlier, but the jumpers are placed in the following way: U1-V1, W2-U2.

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How to check the operation of the unit

Connection diagram of a single-phase electric motor with direct start-up winding

Connection diagram of a single-phase electric motor with direct start-up winding.

Before starting the assembly, it is necessary to perform an engine performance check. To do this, the motor is first turned on, operated for 15 minutes. If the motor body is very hot, then the reason for this may be:

  • bearing tightness;
  • severe deterioration of the structure;
  • bearing pollution;
  • capacitor capacitance too large.

In this case, the motor needs to be shut off, reduce the capacitance of the capacitor, or perform work on cleaning, repairing the engine, i.e. troubleshoot.

Before turning on a single-phase motor, it is important to check its winding.

Before this, it is necessary to determine which winding is used. Two-phase windings are usually used, which consist of 2 parts:

  • starting winding;
  • main winding.

Such a system is necessary in order to ensure the start of rotation of the rotor. It is for this value that all single-phase motors can be divided into the following categories:

  • single-phase electric motor with a working capacitor;
  • motor with start winding.
Single phase capacitor motor switching circuit

The connection circuit of single-phase capacitor motors: a - with a working capacity Cp, b - with a working capacity Cp and starting capacity Sp.

For example, the unit has 3 outputs, measurements show the following values: 10 Ohm, 25 and 15 Ohm. After the measurements have been carried out, it is necessary to determine the network wires for which the readings will be 10 and 15 ohms. In this case, the 10 ohm wire will be mains, and the 15 ohm wire will be the starting wire, connected via the network.

A variety of single-phase motor windings can also give the following indications: 10, 10 and 20 Ohms. Typically, a similar electric motor is used for household washing machines and other equipment designed for the home. Starting and working windings have the same value, they are performed as for three-phase units.

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Using a magnetic starter to properly connect

It is possible to connect a single-phase electric motor using a special magnetic starter. It is necessary to choose it so that the contact system can withstand the load perfectly while the motor is running. For example, all starters are divided into several types, the greater the value, the more current can pass through the magnetic starter. Such types include (PML series):

Laying windings in the stator of a single-phase electric motor

Laying windings in the stator of a single-phase electric motor.

  • 1 value - 10 A;
  • 2 value - 25 A;
  • 3 value - 40 A;
  • 4 value - 63 A;
  • 5 value - 80 A;
  • 6 magnitude - 125 A;
  • 7 magnitude - 200 A.

When the starting value is specified, it is necessary to choose a 220 V control coil, it can be applied to 380 V - it all depends on the type of equipment. The circuit for the magnetic starter is assembled, then the power unit is connected, 220 V input is made to the contacts. The electric motor is turned on, and the “Start-Stop” button must be connected using the starter’s power contacts.

For example, the phase for the “Stop” button is connected for a closed contact, and for the “Start” button, a connection is made with an open-type contact, and then it is started up on the starter coil. Zero should be connected to the second terminal of the coil of the magnetic starter, for fixing a special block is used, which supplies power to the coil.

When using equipment on electric motors, great attention should be paid to their connection, the choice of an appropriate circuit. Magnetic starters are also used for connection, it is recommended to check the winding before operation.

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