How to check the motor of an electric screwdriver by a multimeter. Damage to the electric part
How to check the electric motor: stages of verification and clarification of faults
When checking the electric motor for serviceability, it should be borne in mind that not all types of motors can be checked in this way. There are a variety of options for the performance of electric motors, most problems can be diagnosed using a multimeter. At the same time, it is not necessary to be a specialist in this area.
Modern electric motors can be divided into several groups:
- Three.Phase asynchronous with a short.Closed rotor. This model is very popular, since the device is simple and is diagnosed when using a conventional measuring tool.
- Asynchronous condenser, short.Term coated with one or two phases. This version is installed in household appliances, the device can eat from a regular network 220 V. Today, such an electric motor is also widespread, it is found in almost every house. In this case, a check for a malfunction is carried out when using a standard tester. A single.Phase model has efficiency and practicality in application.
- Asynchronous, equipped with a phase rotor. The phrase of this motor is carried out quite often, which is associated with a more powerful starting moment. This model is installed on various production equipment and various large equipment. An example will call taps, lifts or various machines.
- Collector that feed from direct current. An audit of such a device is carried out quite often, used in various cars for fans and pumps, janitors. A similar electric motor can burn for various reasons, timely check allows you to determine the problem.
- Collector with alternating current. A manual electric tool was very widespread. To transmit rotation, a collector engine is installed, which can be checked using a megommeter.
Before checking the electric motor with a multimeter, its visual inspection is carried out. Even with a naked eye, you can determine the burned winding or serious mechanical damage. However, if the design has no defects visually, then a special measuring tool should be used.
Dismantling of corner grinders
To check the closure at the stature and rotor, you need to disassemble the engine of the household tool. Consider the implementation of this operation to search for a malfunction of the corner grinder.
- Remove the protective casing by unscrewing one screw on the clamp;
- Unscrew 4 screws and disconnect the gearbox with the engine from the handle of the corner grinder;
- Then, from the side of the gearbox, we unscrew 4 bolts and disconnect the gearbox, along with the engine rotor;
- The stator has remained in the case connected to the power button and power.
Having dismantled and disconnecting the parts necessary for checking, we proceed to their external inspection for the intervaling check.
The principle of operation and the main nodes
Before starting the repair of a screwdriver with your own hands, it is necessary to understand the principle of its work and what parts it consists of. The main difference between a screwdriver and another power tool is the use of a mechanism that stops the rotation of the working part of the device. This happens when the resistance is as configured for the tool. This value is unstable and can adapt. There are two varieties of the device:
Regardless of the variety of the device, the principle of action is the same for them and is built on the transfer of the rotational moment. He determines which fixed tool will be able to tighten the screwdriver. To increase the rotating moment in the devices, gearboxes with a large gear ratio are used, but the speed of rotation is reduced. In screwdriver operating from the network of alternating current, the value of the rotational moment correlates with the power consumption of the tool. The main parts underlying the screwdriver device, whether it be makita, hitachi or bison, as follows:
- Electric motor;
- Push button;
- Revolution control regulator;
- The electronic unit;
The electric motor rotates with the set speed of the spindle, using a planetary gearbox for this. The torque is regulated by the coupling, and a clamping cartridge or a hexagonal holder is put on the spindle. This cartridge is installed in a shift device called “Bit”. Screwed by a screwdriver by an electronic circuit and switching a reverse.
Reverse occurs due to a change in the polarity of power. A single.Phase collector electric motor of continuous current is used as an engine. Such an engine is designed to connect to the AC network. The winding of the excitement is connected sequentially to the anchor winding and is divided into two parts. One turns on to the anchor, and the other after it.
The tool uses a planetary type gearbox. The reducer includes sunny and ring gears, satellites, drive. The shaft of the electric motor rotates the solar gear, which transfers the torque to the torch, and they already directly affect the drive.
The gearbox is produced by a single and two-stage. In the second case, a double drive associated with the shaft is used. The design of two drove and satellites is located in the middle of the ring gear. It is fixed through special grooves on the case. Along the entire perimeter, the ledges of the ring gear rest against the spring.Loaded balls through the ring. The load regulation mechanism acts on the ring through the controlled spring, the effort of which changes by rearranging the regulator.
The revolutions are controlled using a pulsed circuit collected on a microcircuit with a wide-mulse modulation (PWM). The controller controls the field transistor operating in the key mode. The frequency of pulses changes using a variable resistor. The resistance of the resistor depends on the effort that is applied to the button.
Screwdriver clutch is a rattle. If the load on the cartridge exceeds the permissible value, then the load regulator is triggered. The force of the spring becomes insufficient to hold the ring gear, and it leaves the balls. The electric motor begins to rotate the gear of the idle. When switching to the electric drill mode, this gear is turned off and does not participate in the work.
As a power source, the battery with a voltage of 12 V or 18 V is most often used. It characterizes the power of the device.
The battery consists of several elements installed in one case and connected in series. The case has a special latch that allows you to quickly extract the battery.
How to call the electric motor multimeter
The electric motor is the main component of any modern household electrical engineering, whether it be a refrigerator, a vacuum cleaner or another unit used in the household. In the case of any device failure, it is first necessary to establish the cause of the breakdown. To find out if the engine is in good condition, it must be checked. It is not necessary to carry the device to the workshop for this, it is enough to have a conventional tester. After reading this article, you will learn how to check the electric motor with a multimeter, and you can cope with this task yourself.
Which electric motors can be checked by a multimeter?
There are different modifications of electric engines, and the list of their possible malfunctions is quite large. Most problems can be diagnosed using the usual multimeter, even if you are not a specialist in this area.
Modern electric motors are divided into several types that are listed below:
- Asynchronous, for three phases, with a short.Circuit rotor. This type of electric power units is the most popular thanks to a simple device that provides easy diagnosis.
- Asynchronous capacitor, with one or two phases and a short.Closed rotor. Such a power plant is usually equipped with household appliances, which is enlisting from a regular 220V network, the most common in modern houses.
- Asynchronous, equipped with a phase rotor. This equipment has a more powerful starting moment than engines with a short.Closed rotor, and therefore it is used as a drive in large power devices (lifts, taps, electric shoes).
- Collector, direct current. Such engines are widely used in cars, where they play the role of a drive of fans and pumps, as well as glass windows and wipers.
- Collector, alternating current. These engines are equipped with a manual power tool.
The first stage of any diagnosis is visual inspection. If even the burned windings or the broken parts of the motor are visible with the naked eye, it is clear that the further check is meaningless, and the unit should be taken to the workshop. But often the inspection is not enough to identify problems, and then a more thorough check is needed.
Repair of asynchronous engines
Asynchronous power units for two and three phases are most common. The order of their diagnosis is not exactly the same, so you should dwell on this in more detail.
There are two types of malfunctions of electrical units, and regardless of their complexity: the presence of contact in the wrong place or its absence.
Capacitors for electric motors
The composition of a three.Phase motor operating from alternating current includes three coils that can be connected in the form of a triangle or star. There are three factors that determine the performance of this power plant:
The closure on the case is usually checked using a megammeter, but if it is not, you can do with an ordinary tester, putting on it the maximum value of the resistances. Megaom. There is no need to talk about high accuracy of measurements in this case, but approximate data is possible.
Before you measure the resistance, make sure that the engine is not connected to the mains, otherwise the multimeter will become unusable. Then you need to calibrate, putting the arrow on zero (the probes must be closed). Check the serviceability of the tester and the correctness of the settings, briefly touching one probe of another, it is necessary every time before measuring the size resistance.
Attach one probe to the electric motor body and make sure that there is a contact. After that, remove the device’s readings, touching the engine with the second probe. If data is within the normal range, connect the second probe with the withdrawal of each phase alternately. A high resistance indicator (500-1000 or more MOMs) indicates good isolation.
How to check the insulation of windings is shown in this
Then you need to make sure that all three windings are intact. You can check this by calling the ends that go into the box of the electric motor conclusions. If a cliff of any winding is detected, the diagnosis should be stopped until the malfunction is eliminated.
The next checkpoint is the definition of short.Closed turns. Quite often, this can be seen during a visual examination, but if outwardly the windings look normal, then the fact of a short circuit can be established by unequal consumption of electric current.
Two.Phase electric engine
Diagnosis of power units of this type is slightly different from the above procedure. When checking a motor equipped with two coils and sales from a conventional power grid, its winding must be raised using an ohmmeter. The resistance indicator of the working winding should be 50% less than that of the starting.
The resistance to the case must be measured. Normally it should be very large, as in the previous case. The low resistance indicator indicates the need to rewind stator. Of course, to obtain accurate data, such measurements are best carried out using a meter, but such an opportunity at home is rare.
Checking collector electric motors
Having dealt with the diagnosis of asynchronous engines, we proceed to the question of how to call the electric motor by a multimeter if the power unit belongs to the collector type, and what are the features of such checks.
DIY electric screwdriver renovation rules
The three main reasons that lead to the fact that you have to repair an electric screwdriver with your own hands are:
- If the battery is not working or not charged.
- The inclusion button does not function.
- The electric motor shields were worn out or the anchor burned down.
Any electric screwdriver has the following basic elements in its design:
How to check the engine and button with a multimeter
To determine the performance of the button and engine, the multimeter is used.
To perform the diagnosis of the motor, gearbox and wiring connecting the part with the trigger button, disconnect, and then measure the resistance of the anchor winding. If there are no indications, this reports the break in the winding. If the numbers on the screen are very low, a short circuit has occurred.
To check the button, the wiring connecting its input terminals with the battery with a multimeter, twisted, and tester probes are connected to the outputs. The device is transferred to the resistance measurement mode and included. If the values on the display are close to zero, the part is in good. With a breakdown, the screen shows infinity.
Consistent and parallel connection of elements
The battery of an electric screwdriver consists of separate elements. The electrical circuit of such elements can have a circuit of both parallel and sequential connection (rice.2).
You can check the serviceability of the elements after a certain time of their charge, there is, the presence of voltage on each element, or the battery in general, is checked. If when measuring the element voltage, the value on the display of the “multimeter” device will be a smaller indicator (for example, not 1.2V, but 0.8V), it means that this element is lost electrochemical properties in the process of operation. Such elements are subject to their replacement. Electrochemical elements for the battery
It is necessary to select in accordance with their technical characteristics, that is, by voltage and current. The indicator on the body of the extracted battery element for example is:
Performed by jumpers. With this replacement, you will need a soldering iron, solder tin and soldering acid.
This topic provides an example from its own practice.
So, in front of us in the photograph depicts an electric screwdriver bort.
Initially, to find a malfunction of an electrical screwdriver, you can check the overall resistance of its electrical circuit.
Before checking, the start button must be turned on, that is, fix the button, as shown in the photograph.
Then, the multimeter device measure the resistance of the electrical circuit of the electrical screwdriver.
To do this, the multimeter device is installed in the resistance measurement range, then touched the displayed contacts (on the handle) of the electrical screwdriver, as shown in the photograph, when measuring the display of the device indicates a resistance that is not comparable to the operation of this power tool. The resistance value here is the indicator. Short circuit. According to the display of the device, it is clear that this electrical screwdriver is faulty. But we need to establish a specific reason. What is the malfunction?
To find the cause of the malfunction, it is necessary to disassemble the electric screwdriver and check the diagram of electrical connections.
Scheme of electrical screwdriver
In this electrical circuit, as we may notice, the transistor consists.
The transistor is installed on a metal plate that serves to remove heat when heated. The transistor is checked for the presence of resistance between the transitions (emitter. Collector. Base). To check the transistor and do not focus on the type of transistor (N-P-N, P-N-P), two of any transistor legs are checked in both directions.
In this way, the lack of conductivity between the collector and the base of the transistor was established. But as a result of which transistor could fail? We diagnose for individual electrical connections, namely, for the electric motor of an electric screwdriver.
The photograph indicates an unacceptable resistance value for the electric motor. What exactly is the cause of the malfunction of the electric motor? We look further.
Electric motor of an electric screwdriver. Collector, working from direct current. On the end part of the electric motor cover there are graphite brushes. Graphite brushes in this example, in good condition. Here you also need to check the conductivity of contact connections (wire. Brush).
The rotor of the electric motor consists of windings interconnected sequentially. The stator of the electric motor is a permanent magnet with two poles, that is, the electric motor stator has no windings.
You can make sure that. Metal objects are attracted by the electric motor with the electric motor.
From this we can conclude that in a malfunction of the electric motor, there is a breakdown of isolation between the wires of the rotor windings.
Well, here is the reason for the breakdown of an electrical screwdriver, which is a malfunction:
It remains only to replace the corresponding details.
Electric screwdriver is a multifunctional power tool that helps with furniture assembly, small repair or in other tasks. But this device breaks over time. If there is no money for repair or purchase of a new device, you can try to fix it with your own hands. To do this, you should know what malfunctions are characteristic of this type of tools and understand how to correct them correctly.
Which electric motors can be checked by a multimeter
If there is no mechanical damage in the engine, which is usually determined visually, then its malfunction in most cases is due to the following:
Both defects are detected by a multimeter. Difficulties arise only when checking direct current engines: in most of them the winding has almost zero resistance and it has to be measured with an indirect method, for which you will need to collect a simple scheme.
- Three.Phase asynchronous engines operate with single.Phase nutrition.
- Asynchronous one- and two-phase with a short-closed rotor capacitor. Most of the engines of household appliances belong to this type.
- Asynchronous with phase rotor. Such a rotor has a three.Phase winding. Engines with a phase rotor are used where adjustment of the speed of rotation and lowering the starting current is required: in crane equipment, machines, etc.
- Collector. Used in manual power tools.
- Three.Phase asynchronous with a short.Closed rotor.
The popularity of the latest type motors is explained by a number of advantages:
Repair of an electric screwdriver engine
Before the assembly of the electric motor of an electric screwdriver using a thin wire that serves as a clamp, each brush is diverted in the brush holder, the lid is installed in the same place. At the same time, brushes release and envelop the housing at the edges, which contributes to the best pressing of the back cover.
If an electric screwdriver has been working for a long time, then this may be accompanied by the process of curvature of the shaft related to the gearbox due to strong loads and pressing the tool. The cartridge, blaming the shaft, sometimes causes a strong beating during the operation of the device. Supporting sleeve or shaft bearing can be very worn out. As a result of damage to the sleeve or only the bearing, and not only them replace the shaft.
Sometimes the engine is not possible for a certain fraction of a second, that is, its sharp stop occurs. This reason may be the failure of the gearbox. Often a malfunction occurs due to a breakdown of a pin that serves as a mount to satellite. It is possible to replace the drive or entirely a gearbox that may fail if the teeth of the gears are worn out.
If, after all the above operations, the malfunctions were not detected in the device, then it is necessary to verify the anchor condition and the serviceability of the engine brushes. In this case, the engine should be disconnected from the switch button, and then measure the resistance by attaching a tester of any kind to the engine wires. If the resistance in the circuit is completely absent, then this may indicate that the brushes are worn out. The malfunctions in the anchor of the engine are not excluded, which may be associated with the gap of the winding. At the same time, such types of problems can rarely meet.
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If the engine anchor is completely burned out, then the device engine is subjected to the full replacement. If only the engine brushes occurred, then it is better to make the repair of the device yourself. Before starting the repair, it should smoothly open the body of the engine of an electric screwdriver so as not to damage its edges. All stages of work related to the replacement of brushes are indicated above. It is possible that the anchor’s bushings were worn out at the expense of the magnet, which came off and began to contact with the anchor. Dripping a drop of special oil to the sleeve, you should turn off the engine to wait until the oil has dispersed through all the bushings. At the same time, he still requires replacement over time.