For electric drive purposes, the rotor may be in direct connection with the mechanism or through gearboxes or other mechanical energy transmission systems. There is no need to be afraid, because in the volt network it is impossible for a critical voltage to arise that would damage the motor windings. If you turn on two starters at the same time, a short circuit will occur - a short circuit on the power contacts of the starter.
The rotor is a bearing-supported structure with an impeller for ventilation. And if there are six terminals, then the motor can be connected according to any circuit. How to connect an asynchronous motor
For example, if it is written on the unit that the rated current that can flow through its windings is 6 amperes, then the capacity of the working capacitor will be 76 µF. In the photo you can see screw pumps with additional fans on electric motors.
Thus, connecting a three-phase motor to a three-phase network can be done in various ways. You can select the capacitor capacity for connecting a three-phase motor to a single-phase network based on the table below.
The circuit diagrams are quite simple.
In the circuit, a single-pole circuit breaker is used to turn on the electric motor, but its use is not necessary; you can turn on the electric motor directly to the network through an outlet using a regular plug or, for example, turn it on through a regular light switch. If you connect a European motor with a star, it will immediately burn out under load. The easiest way is to connect the electric motor through a frequency converter designed for power supply from network B. Triangle diagram.
Connecting a 220V electric motor with a triangle and a star. Demonstration of work. Which type is better?
Using a frequency converter
When the float closes the circuit, the starter coil circuit will close and the electric motor will turn on; when it opens, the power to the electric motor will be turned off. That is, you can only connect to it an electric motor that has a supply voltage of 2. In a three-phase network, usually these are motors with six contacts in a junction box, the windings of which can be connected either in a star or in a triangle. This condition has a negative impact on the insulation of wires. But this only means that the jumper mechanism is already implemented in the engine itself.
The delta connection is made to the second starter, and the star connection is made to the third. It functions as a locking element and prevents the circuit from breaking when the START button is turned off.
The principle of operation of the circuit is a little more complicated, let’s look at it in dynamics. Connection to a single-phase network A three-phase unit can be successfully connected to a single-phase network.
The duration of the work cannot be predicted. The fact is that a three-phase network does not always have the usual voltage in V.
Below you see the brno and the terminal blocks that are installed in it. This means using winding pin switches to obtain a choice of one of two winding connection options.
In this case, it must be installed in the gap between the third contact of the triangle and the neutral wire. Connection to a single-phase network To connect a three-phase electric motor B to a single-phase network B, a circuit with phase-shifting starting and operating capacitors is most often used. How to connect a magnetic starter. Connection diagram.
Triangle connection and its advantages
The principle of the “triangle” connection is to connect in series the end of the winding of phase A with the beginning of the winding of phase B. And then, by analogy, the end of one winding with the beginning of another. As a result, the end of the phase C winding closes the electrical circuit, creating an unbroken circuit. This scheme could be called a circle, if not for the mounting structure. The triangle shape is given by the ergonomic placement of the winding connection.
When connected by a “triangle” on each of the windings, there is a linear voltage equal to 220V or 380V.
The main advantages of using the triangle scheme:
- Increasing the power of electrical equipment to the maximum value;
- Using a starting rheostat;
- Increased torque;
- Large traction forces.
Flaws:
- Increased starting current;
- When running for a long time, the engine gets very hot.
The “triangle” method of connecting motor windings is widely used when working with powerful mechanisms and the presence of high starting loads. A large torque is created due to an increase in the self-induction EMF caused by large flowing currents.
Connecting a three-phase motor to a single-phase network using a triangle diagram
Connection diagrams
They are recommended for connection to our volt networks using the delta method only. On the main K1 - power is connected to the stator windings.
Connection diagrams When a three-phase motor is connected to the network, then each of its windings is powered from one phase.
Therefore, if there are three phases, it is recommended to connect the appropriate three-phase equipment. Do the same for the other terminals.
When starting an asynchronous motor, the first and second groups are closed. Switch SA1 is responsible for reverse. There are two options here: Nominal voltage 3xV - you're in luck and use the circuits above. There are two connection schemes: Star.
Now you know how to connect a three-phase motor to Volt, as well as what is needed for this. The circuit consists in the same way as in the non-reversible circuit, the only thing that is added is a reverse button and a magnetic starter.
The middle one must be permanently connected to the working capacitor. To prevent this situation from happening, the magnetic starter is additionally equipped with auxiliary contacts, which are called self-retaining. Phase power is connected to the node points of the ends of the windings. But it is worth considering that a non-latching switch must be installed in the wire that is connected between them. To prevent this, the magnetic starter is equipped with another additional contact connector, the so-called self-retaining contact.
This is the same if you twist an aluminum wire with a copper one. In this article we will look at ways to connect an electric motor to achieve its maximum power and performance, while ensuring its safety from a technical point of view.
But it exists, so it makes sense to say a few words about it. It forces the rotor, which is located in the magnetic field of the stator, to rotate. This condition has a negative impact on the insulation of wires. How to simply connect a three-phase motor with a triangle and a star to a 220 network, through a capacitor.
Optimal choice of motor connection
The conversion of a “star” into a “delta” in an asynchronous electric motor, as well as the ability to repair the motor windings, and, compared to other motors, low cost, combined with resistance to mechanical stress, have made this type of motor the most popular. The main parameter that characterizes the advantage of asynchronous motors is simplicity in design. With all the advantages of this type of electric motor, it also has negative aspects during operation.
In practice, three-phase asynchronous electric motors can be connected to the network in a star and delta configuration. A “star” connection is when the ends of the stator winding are wrapped around one point, and a 380-volt network voltage is applied to the beginning of each winding; schematically, this type of connection is indicated by the sign (Y).
Read also: Direct acting pressure reducing valve
If the “triangle” option is selected in the switching box for connecting the electric motor, the stator windings must be connected in series:
- the end of the first winding - with the beginning of the second;
- connecting the end of the “second” to the beginning of the third;
- the end of the third - with the beginning of the first.
Using a star-delta circuit
General rules for connecting an electric motor through a capacitor.
The connection of electric motor B to B is made through a capacitor. But sometimes you need to make electrical measurements.
In this case, it does not really matter which of them closes the contacts first. Such a machine can turn off the engine only in the event of a short circuit or jamming, which often does not provide the necessary protection.
Attention, magnetic starters K2 and K3 should not be turned on at the same time, otherwise an emergency shutdown of the circuit breaker will occur due to the occurrence of an interphase short circuit. With the triangle option, all ends of the windings are connected in series to each other. Opposite phases are supplied to the free ends of the windings.
See also: What does the letter l on a switch mean?
Connecting a 380 to 220 electric motor with your own hands: diagram
The ends of the windings in the diagrams are numbered from left to right. This is the topic that this article is devoted to. Why is it better to select starting capacitors empirically, starting with the smallest?
If the engine power exceeds that indicated above, then you will also need a starting capacitor. This value increases sharply at start-up, which negatively affects the winding. In this case, it will be possible to achieve only a percentage drop in power.
Possible connection diagrams for electric motor windings
Selecting a capacitor There are no universal capacitors that would fit all units indiscriminately. To implement the intended use parameters, a number of starters K1, K2, K3 are used.
The main reason is that the contacts of the button are burnt, because when starting the engine, a starting load with a large current appears. What is it used for? Related topics:. These circuits precisely determine the temperature conditions of the windings and the load on the insulation. Connection diagram for a four-pole RCD in a three-phase network without using a neutral
Star connection and its advantages
Each of the three working windings of the electric motor has two terminals - the beginning and the end, respectively. The ends of all three windings are connected to one common point, the so-called neutral.
If there is a neutral wire in the circuit, the circuit is called 4-wire, otherwise, it will be considered 3-wire.
The beginning of the terminals is connected to the corresponding phases of the supply network. The applied voltage on such phases is 380 V, less often 660 V.
The main advantages of using the star scheme:
- Stable and long-term non-stop operation of the engine;
- Increased reliability and durability by reducing equipment power;
- Maximum smooth start-up of the electric drive;
- Possibility of exposure to short-term overload;
- During operation, the equipment housing does not overheat.
There is equipment with internal connection of the ends of the windings. Only three pins will be output to the block of such equipment, which does not allow the use of other connection methods. Electrical equipment made in this form does not require competent specialists for its connection.
Connecting a three-phase motor to a single-phase network using a star circuit
