Nowadays, asynchronous units are used mainly in motor mode. Devices with a power of more than 0.5 kW are usually made three-phase, lower power - single-phase. During their long existence, asynchronous motors have found wide application in various industries and agriculture. They are used in the electric drive of hoisting-and-transport machines, metal-cutting machines, conveyors, fans and pumps. Less powerful motors are used in automation devices.
Necessary
ohmmeter
Instructions
Step 1
Take a three-phase induction motor. Remove the terminal box. To do this, unscrew the two screws with a screwdriver that secure it to the case. The ends of the motor windings are usually brought out to a 3 or 6 terminal block. In the first case, this means that the phase stator windings are connected "delta" or "star". In the second, they are not connected to each other. In this case, their correct connection comes to the fore. Inclusion by a "star" provides for the union of the winding terminals of the same name (end or beginning) to the zero point. When connecting with a "triangle", connect the end of the first winding with the beginning of the second, then the end of the second - with the beginning of the third, and then the end of the third - with the beginning of the first.
Step 2
Take an ohmmeter. Use it when the leads of the induction motor windings are not marked. Determine three windings with the device, designate them conventionally I, II and III. Connect any two of them in series to find the beginning and end of each of the windings. Apply an alternating voltage of 6 to 36 V. To the two ends of the third winding, connect an alternating current voltmeter. The appearance of an alternating voltage indicates that the windings I and II were connected according to, if not, then the opposite. In this case, swap the terminals of one of the windings. Then mark the beginning and end of the I and II windings. To determine the beginning and end of the third winding, swap the ends of the windings, for example, II and III, and repeat the measurements according to the above method.
Step 3
Connect a phase-shifting capacitor to a three-phase asynchronous motor, which is included in a single-phase network. Its required capacity (in μF) can be determined by the formula C = k * Iph / U, where U is the voltage of a single-phase network, V, k is a coefficient that depends on the connection of the windings, Iph is the rated phase current of the electric motor, A. Note that when the windings of the asynchronous electric motor are connected by a "triangle", then k = 4800, "star" - k = 2800. Use paper capacitors MBGCH, K42-19, which must be rated for a voltage not less than the voltage of the supply network. Remember that even with a correctly calculated capacitor capacity, an asynchronous electric motor will develop a power of no more than 50-60% of the nominal.
