The motor is tested with a tester in hand. Usually, all contacts are called, resistance values are measured. With a small level of knowledge about the internal structure of the collector and asynchronous motors it is possible to determine the failure. Often the security system fails. This is especially true of household appliances. Before you check the grinder engine, just wait a short time. In some models, there are temperature relays that do not allow the device to turn on until the motor cools down. Today we will talk how to check up the electric motor.
What you need to test the motor
Of course, you will need a set of screwdrivers with various bits. A modern manufacturer protects its own products. Toaster, hair dryer or multicooker - to open the case you need more than one size and type of nozzles. Used conventional screws under the cross, TORX, asterisk and others. The part is non-standard, but with patience the right head will be found. Fit sets of bits of different configurations.
Most engines - no frills in the design of fasteners. Usually heads are made under hexagons, crosses or splines. As for the brushes of the collector electric motors, the replacement is made with the help of an improvised tool. It will take patience.
Electric motor type
When it comes to a meat grinder or vacuum cleaner, the engine inside is a collector. On the shaft there is a sectional drum for switching the rotor windings, over which the current collector slides. It looks like a cylinder of copper color, the side of which is divided into rectangles. Included with the home appliance are spare graphite brushes. And the maintenance of such an electric motor is reduced to their replacement, periodic cleaning of the copper drum. If graphite builds up between the sections, sparking increases, a circuit may occur between adjacent windings.
Collector electric motors are used because of the high torque at the start. Their speed is easily regulated by changing the cut-off angle. If two sharply differing modes are required, this is ensured by different stator windings. When spinning, the electric motor starts to work at full. Specific motors can differ significantly from typical ones. For example, they say that the collector engine has only two contacts, because the current flows continuously through the windings.
In practice, not only the washing machine's motor has two switch-on options, controlled by a special relay( abrupt change in the speed of operation at the same supply voltage), but there are tachometer leads. This is a sensor that measures the revolutions of the shaft to correct the current cut-off angle. In addition, collector motors are often supplied with spark ignition schemes and speed adjustments as the shaft load changes:
- Sparks are extinguished through varistors. Their resistance drops sharply with increasing voltage. Being connected in parallel to the brushes and shorted to the motor housing, they close the circuit( right through the casing) during abrupt voltage surges. The described property protects the windings from the vagaries of the power grid.
- As for the adjustment of the rotational speed under the load on the shaft, it has long been noted that with increasing resistance to rotation, the level of sparks rises. A special circuit tracks this and reduces the cut-off angle, as a result the shaft speed increases again. So fine adjustment under insignificant deviations of turns from nominal is made. This technique is often found in food processors, where the grater is capable of chopping cabbage or making idling. As for, for example, vacuum cleaners, in the simplest models there is only extinguishing of sparks.
Let's talk, how to understand, there is a device with a collector or asynchronous motor nearby. As it is easy to guess, the first are very noisy. However, blenders are not so much noticeable. Collector engines are used where there is a large load at the start. We loaded the blender, turn it on. There is resistance to the rotation of the shaft, which is required to overcome. An asynchronous motor would have to significantly complicate the design, mass-dimensional characteristics would suffer greatly. Therefore, mainly in household appliances collector engines.
This applies even to powerful kitchen hoods. Although the simplest models are asynchronous motors with a single winding. This type is found in fans. Finally, DC motors are often present in computer technology. The language does not turn to be called asynchronous, although the principles of operation are similar. The blade is so light that induction induced by permanent magnets is enough to rotate. The start comes from random air turbulences. The video is uploaded to YouTube, where the coil field is replaced by permanent magnets, and the fan( !) Still turns. In such engines, the fault is monitored by the winding of the windings, there is nothing more to break here.
So, the conclusions:
- In household appliances for the most part collector engines are used. Exception: fans, hair dryers, low-power kitchen hoods.
- Collector engine is characterized by the presence of graphite brushes. Sectional copper drum produces this type. If these signs are absent, the motor is asynchronous.
- Maintenance of the collector engine is reduced to work with brushes and section drum. In asynchronous burn only windings and thermal fuses.
Start of repair of the motor.
. If the type of engine is determined, you can begin to determine the number of phases. By the way, industrial-type asynchronous motors are often performed in ribbed high-power cylindrical bodies - an additional key feature. Brushes are fragile, collector engines are trying not to apply here. As for asynchronous, copper is not afraid( as opposed to graphite) shaking, plants are mainly equipped with them. Raising torque at the start and improving other characteristics, special design solutions are used. For example, the rotor winding is performed in two layers. The bottom one works exclusively at the start, while the low frequency induction currents. When the shaft is unwound, the auxiliary layer is turned off from the work process. Of course, the same happens when the speed is reduced.
A massive steel case usually indicates that the motor is asynchronous. Consider: dust in the workshop would have a negative effect on the quality of brush contact with the surface. Although in vacuum cleaners the air flow is immediately used to cool the windings, do not forget that thorough filtration is performed. If you take the best Dyson models, there the quality of cleaning is such that it is allowed not to change the HEPA steps during operation. We are talking about particles of 5 microns in size. Conclusion - if the collector engine is used in adverse conditions, special measures are taken.
Maybe you should separate the brushes from the room at all? But during the work of the equipment a lot of heat is released. Forced cooling required. Otherwise, it would be extremely easy to determine the breakdown - the overheat protection circuit would constantly break down: relays and thermal fuses. Either the windings are lit. Read the instructions in the papers. As a rule, there is a mass of indications. Therefore, it is easy to determine what has broken.
If you take meat grinders, the authors like to cite examples from the products of the Polish company Zelmer, where in the model range the appreciation is conducted on the basis of security. For example:
- The cheapest meat grinders go without protection. Yes, the collector is equipped with varistors, the fact of the presence of a fine adjustment circuit of turns is not excluded. But the engine is virtually defenseless in front of an inexperienced housewife. The instruction prescribes to observe the duration of the operating cycle. The period of work is limited, then a pause is supposed( 2-3 times longer than the period of activity).If the prescription is not met, the windings are burning, you have to look for ways to troubleshoot. But the situation here is sad, you have to either replace the engine or rewind the coils. You can understand what is broken in an uncomplicated way: remove the brushes, ring the stator winding first, then through the rotor sections. The conclusion is simple - where the gap, there is a breakdown. The trouble is complemented by the inability to rewind a single section. In general, a fun weekend is guaranteed. And the price of the new engine bites.
- The second( by increasing cost) type of meat grinders is equipped with thermal fuses. These are fusible elements, burning when the temperature reaches, say, up to 135 degrees( often this value appears in the transformers of power units).This is a standard element, it will be found everywhere, starting with floor fans and ending with washing machines. The thermal cutout looks like a blister on the insulation that protects the winding. Sometimes the element is mounted on a specific part of the body( in transformers - magnetic) with the help of a clamping loop of thin steel. Because repair, as a rule, begins with checking the fuse. His task is just to not get up the task to ring the electric motor with a multimeter. The fuse burns, the windings remain intact.
- Finally, expensive appliances( for meat grinders, food processors, blenders, etc.) are supplied with temperature relays. Analogue fuse, only reusable. Inside there is usually a bimetallic plate( there are tablets, other types of sensors), which opens the contact when the temperature has reached a critical one. It's funny that on selected household appliances there is a button for the forced operation of an electric motor, which allows you to bypass the described protection. If you can not wait to practice to understand how to check the motor with a tester, use this booster in pleasure. We believe that the price of a meat grinder does not need to try to speed up the cooking time of cutlets for the arrival of guests. The protection on the relay will turn off when the temperature enters permissible limits. Convenience of equipment in the absence of need with a watch in hand to track the duration of the operating cycle.
If the readers expected to find in the review detailed instructions on how to check the electric motor anchor at home, perhaps some individuals were upset. Authors consider that it is much more important to understand where to look for a malfunction. You can argue with foaming at the mouth, how to check the engine of the washing machine, and it does not pay attention that the pressure switch has failed. And his testimony simply does not allow the equipment to start. Similarly, before checking the refrigerator engine, familiarize yourself at least approximately with the device of the start-up relay, which is responsible for the correct switching of the windings at the start and after the acceleration of the shaft. As for questions of dialing, this is a short matter. It is much easier than winding a section on the rotor of a Bulgarian collector engine.