It is easy to guess: there is an electric motor inside the meat grinder, supplemented with a speed control circuit. If we put aside the cases when it is necessary to replace the protective sleeve, clutch, repairing meat grinders with their own hands, it concerns the knowledge of the theory and practice of AC motors. In electric motors, collector structures with consumer electronics are more often used, asynchronous dominate in industry. Beginners will ask where the authors took the information. The answer is: according to the service information of the firm Ariston, since the 90s of the last century, collector motors have been replacing asynchronous in the consumer segment. Today, the percentage of the first reaches 85 total. On this rainbow note, we will begin consideration of AC electrical machines and control methods.
One often hears a statement: collector motors work equally well from AC and DC.Let's say more: the alternating current loses some of the power, passing the stator and rotor inductors, the inductance tries to delay the frequency.50 Hz too much for a simple wire coil with varnish insulation. Often the stator windings pull each separately as it is. You can power one. Power suffers, losses are reduced, reaching minimum sizes.
How easier to adjust the asynchronous motor. Found two methods used by meat grinders:
- Voltage amplitude change.
- Switching windings.
It is clear that the first method requires the inclusion of additional elements in the scheme. I wanted to notice about this! It was possible to read on the forum about the domestic speed controller of the induction motor, as if there were only resistors. The author hinted at the presence of a resistive voltage divider. But! When the active element works in linear mode - most regulators are built with thyristors - resistance is far from infinity or short circuit. Put radiators, protecting semiconductor keys, touch on the topic below. We want to bring to the attention of the reader: there will always be losses.
Low blood is not enough. The meat grinder device contains a motor with two windings, a starting capacitor, the rotor is represented by a drum, we see a 100% asynchronous motor with a squirrel-cage type squirrel cage rotor. Let's meet the circuit with the switching windings. As follows. One coil is wound around the periphery, switched on through a capacitor, providing the desired phase shift. The second is wound at an angle of 45 degrees around the circumference, the phase shift is devoid. One is divided by two unequal windings. Each can be included separately, in parallel( together).Gives three speeds.
Add a topic to asynchronous motors. The manual for repairing meat grinders will forget to mention a trifle: inside the windings, a thermal fuse is often installed, designed for 135 degrees. Foreign elements are more often decorated with the letter F, the figure has little to do with Fahrenheit. Unlike Elenberg transformers, where the braid honestly writes: inside the thermal fuse, asynchronous motors are often not mentioned. Call the windings: one suffers a break, patiently conduct an inspection on the subject of different elements hidden between the wire. It is not easy to do, believe me. The first glance shows only copper, the second - copper, the third - an element of protection is seen.
Thermal fuse found, should be soldered, ring out. With a positive test for breakage, get a new one, solder in place of the old one. Guess why you can not short out? Right! The next time, the non-thermal fuse will burn out - the induction motor, the hassle will increase. Similar radio elements are in many products, there are no special requirements. Surely there is a suitable copy on the flea market. Self tinkering beware. As is the case with the regulation of the speed of asynchronous motors. The method of dividing the voltage with a thyristor is suitable, in practice a current cut-off is used.
Let's describe the process:
- The supply voltage is supplied bypassing the brushes in series on the rotor and stator. The direction of movement of the shaft is determined by the direction of the windings.
- The current passes through a thyristor key controlled by a sum of voltages.
The commutation signal generation source predetermines the circuit complexity. Collector engines sparkle. When switching sections, an anti-EMF occurs. Directed opposite to the power supply. Apply feedback. Through a capacitor, the back-EMF diode is added to the control electrode of the thyristor. More amplitude, less open gateway. The motor starts, or the load increases - the speed decreases. The amplitude of the self-emf becomes smaller, the key current increases, the engine again goes into mode. There is no need to say how important it is to maintain consistency of turns, the schemes solve the named problem. It is clear that part of the power is lost on the key, the inevitable payment of stability. Through a variable resistor, you can separately adjust the speed. Who is interested - good options can be found here k88882.narod.ru/dom007.html.
We repair AC motors
The meat grinder is opened, we begin to inspect the engine. It is necessary to measure resistive input resistance. If a capacitor is seen in the circuit, we define it as a break, misinterpret it, considering it a breakdown. To repair the grinder, specify the proposed type of engine. Traditionally collector, it is easy to recognize, thanks to the characteristic drum, broken by segments, two graphite brushes fit diametrically. Asynchronous motors sell variants with a short-circuited, phase-wound rotor. In the first case, the rotating part is devoid of electrical contact with the stator, the power source, in the second - there is a pair of supply rings for the rotor windings.
The difference between the asynchronous motor with the phase rotor - the shaft has no segmented drum, there is no pair of brushes. Repair of electric meat grinders is carried out according to the type of engines. At asynchronous input is ringing anyway. Collector engine is not enough.
We call the section, rotate the shaft, measuring the resistance of each step. Values must be equal. The process stops - the turnover is completed. In collector engines, the stator is often placed on one coil. It is connected by a magnetic conductor with a rotor, is represented by a core with turns of wire. Repair grinders with their own hands will be a freebie. Even if the wire has burned in the center, always buy a new bundle with varnish insulation in the store, winding the volume you need yourself.
Use a device formed by two pairs of racks installed vis-à-vis on a long board. On each rotating axis. One contains a new coil, the second - a coil of wire. Here you wind the old choke to localize a break, how many turns to wind, what is the length of the wire. Most people use a pen, like an old street organ, it is allowed to use a screwdriver drive, a drill. Determine the speed so that it is convenient to lay the turns tightly. The second hand guides the shuttle from side to side, from edge to edge of the coil. In conclusion, we ring the coil, measure the electrical resistance.
Repair of asynchronous motors defined design. The stator can be repaired. The configuration of the rotor windings difficult( if any).However, if the forces are up to date, time, the desire to engage - it is impossible to stop the master. Let them be spent a day, the engine works again as part of a meat grinder.
- Direction of winding.
- Number of turns.
Three whales will help to properly position the wire, to unite with adjacent coils is allowed, with the help of soldering, imposing insulation in place of the electrical connection. The main causes of grinder breakage are the consequences of improper operation. Often there are two gross violations by users of household appliances:
- Exceeding the permissible time of continuous operation, the underestimation of the duration of rest. The parameters are not advertised by manufacturers, not all meat grinders contain protection against overheating. Users are deprived of information about the features. Mistresses lose blenders. The motor breaks easily.
- The second misstep is the ingress of hard bones under the auger. Repair Zelmer grinder is to replace the protective coupling. Sometimes it is necessary to purchase a set of spare parts.
Capacitors are lit, blown up( electrolytic on filters).Call, do a visual check: one side sticks out. The butt is pressed by a cross-shaped recess. Curved outward. The condenser burned out - consider it a favorable outcome. All successful repair!