How to wire an angle grinder with a multimeter. Indicator as a way to check for short-circuit turns

Checking angle grinder stator for inter-turn short circuits video

An angle grinder is a construction tool used in cutting and edging various hard materials such as stone, metal, wood, etc.д.

The rotor is the part of the angle grinder motor that rotates during operation, driving other components and parts of the power tool. The quality of cutting and grinding and how long the machine will operate depends on the performance of this important part.

Control of the rotor is carried out in two ways. preventive inspection and by determining the cause of failure, if a breakdown has already occurred.

Checking and repairing the angle grinder’s armature with your own hands 1

Almost all appliances used in the home use asynchronous electric motor. An important advantage of this type of motor is that when you change the load on it, the speed does not change.

This means that if, for example, long and without stopping to cut stone with a household angle grinder, no external signs of motor overload will not be noticeable. The speed of the disc is constant and the sound is monotonous.

Only the temperature will change, but you may not notice it if your hands are wearing gloves.

The commutator of an asynchronous motor is sensitive to overheating

With inattention, the advantage can turn into a disadvantage. Asynchronous motors are very sensitive to overheating, excessive operating temperatures will cause the insulation on the rotor windings to melt.

At first the motor will run intermittently, and then. when an inter-turn short-circuit occurs. the motor will stop altogether. It is worth several times to overheat the angle grinder motor and, most likely, the armature will melt.

Also, the high temperature causes the contacts connecting the primary winding wires to the collector to desolder, leading to an interruption in the electrical current flow.

How to determine the angle grinder armature malfunction

Signs of breakage of the angle grinder armature are: increased brushes sparking on the motor collector, motor vibration at low speeds, the rotation of the working shaft in different directions. If these symptoms are present, you should stop working with the tool. it’s dangerous. Suspicions are easy to check with simple tests.

Visual inspection from the outside

Troubleshooting should begin with a visual inspection of the angle grinder:

• Perform a general inspection of the tool.
• Look for the integrity of the power cord, the presence of voltage in the socket.
• Check with the voltage indicator that the motor collector and the start button are energized.

Using an indicator, check the integrity of the electric circuit

Visually inspect the inside of the appliance

If there is nothing wrong with the power, but the angle grinder doesn’t work, you have to open the housing to get access to the motor. Disassembly is usually uncomplicated. But it is necessary to adhere to simple rules that will avoid trouble during the reassembly:

• Always disconnect the appliance from the mains before disassembling it.
• Remove the blade and guard from the spindle.
• Open the enclosure in a well-lit area, on a clean tabletop.
• Memorize the location of all the parts and assemblies before disassembling. It is recommended to make a sketch or take a picture of the inside of the appliance.
• Store screws and fastening screws in a separate location so they don’t get lost.

It is best to inspect the motor under a bright light so that all the fine details are clearly visible. The armature should rotate freely about its axis and correctly functioning bearings should not make a sound during operation.

There must be no sign of burned-out wiring on the armature and the windings must be intact, without rips. You can smell the rotor. If there is an inter-turn short circuit, the insulating varnish will burn and give off a lingering, specific smell.

But this diagnosis requires a certain amount of experience.

Run the wire with a tester

If the visual inspection does not yield obvious results, it is advisable to continue the examination with a multimeter.

With the tumbler of the mode switch in the ohmmeter position (200 Ohm range), you need two feelers to “probe” the two adjacent armature lamellae. If the resistance of the windings is the same on all turns, then the windings are intact.

If in any pair the tester shows a different resistance or an open circuit, there is a fault in that coil.

Check the continuity of the coils with a multimeter in resistance measurement mode

A wire break can occur between the winding and the core. You should carefully inspect the connection points between the coils and the collector lamellae at the bottom of the armature, visually check the soldering of the contacts.

Checking contacts with a light bulb

If you don’t have a tester you can get out of this situation with the help of a simple 12 volt bulb. The power can be any, optimally 30-40 watts.

12 volt battery voltage should be fed to the plug of the angle grinder, with a light bulb inserted in the gap of one wire. If the armature is intact, if you rotate the spindle by hand, the light bulb should burn without changing the brightness.

If the glow changes, it is a sure sign of an inter-turn short circuit.

If the bulb does not light, it may indicate the following:

• Brushes may freeze in the non-operational position. The retaining spring has failed.
• There is an interruption in the feeding circuit.
• A short circuit or break in the stator winding has occurred.

There are other ways to diagnose, but they require more sophisticated equipment, which is not usually used at home. An experienced technician will determine the fault with a high degree of accuracy using a “puncher” or a simple transformer with a cut toroidal core and one primary winding.

When the armature can be salvaged and restored with your own hands

If the damage to the armature is ascertained with certainty, the part must be removed from the motor. Disassembly of the motor must be carried out with extreme care, first removing the brushes and disconnecting the power terminals. The rotor and the armature support bearings and the motor cooling impeller are removed and form one piece.

If the armature is heavily wired and has become unbalanced due to overheating, it may be better to replace it completely. Balance problems are indicated by excessive vibration and an uneven hum when the machine is running.

How to rewind the armature. step by step instructions

If your armature is not out of balance and the only problem is a damaged armature, you can rebuild this armature by rewinding the windings. Rewinding a rotor at home requires a lot of patience and care.

Checking the armature with a multimeter

In order to do this check, you need to disassemble the angle grinder and gain access to the armature. You need to put the multimeter in the 200 ohm range and touch the two adjacent blades with the feeler of the device.

If all windings are the same, then the armature is fine. If the resistance on any winding has different values, then there is a fault. The armature winding case should also be checked.

Checking motor windings

An electronic rotor tester is a standard digital multimeter. Before you start testing the short circuit, you should check the multimeter and make sure it is ready for use. Set the switch to the resistance measurement and touch the probes to each other. The meter should read zeros. Set the maximum value of measurement and carry out the test:

• first check the rotor for an open circuit. By touching the black probe to the contact ring, the red probe should test the windings. The instrument pointer goes off, that means that the winding has an open circuit. The rotor should be rewound;
• measure the resistance to determine the possibility of a short circuit to the body. on the contact ring we attach the black probe, the red probe should be tested for short circuit on the rotor case. In the case of low reading of resistance value and sound signal, such armature must be given for repair;
• Carry out a probe test for inter-turn short circuit of the rotor windings. Fixing the probes on the armature contact rings. When the value on the scale of the device, from 1.5 Ohm to 6 Ohm, we checked the serviceable device. All other values on the scale indicate a malfunction of the multimeter.

That’s the end of the rotor check. It is worth recalling once again the basic steps to determine the fault. Before checking, the angle grinder or any other appliance should be de-energized.

Before measuring, visually inspect the housings, insulation and absence of soot on the stator and rotor.

When you disassemble the tool for the first time, write down all your steps. This will allow you to have a clue next time, to avoid unnecessary parts during assembly. If the brushes protrude beyond the edge of the brush holder less than 5 mm, such brushes should be replaced.

You can check the inter-turn short circuit with an electronic tester, i.e. a multimeter.

How to check the stator

The stator is the stationary part of the electric motor, designed to create the electromagnetic field in which the rotor (the moving part of the motor) rotates. Among the possible causes of failure of an angle grinder. angle grinder, “angle grinder”. is a breakage or short circuit of the coil winding (coil) of the stator.

Anchor and stator checker for electrical machines

Another device which can be used to check the stator of an angle grinder is the PUNS 5 machine armature and stator calibrator. The device has a light and sound alarm and makes it possible to detect winding short circuits, open circuits, measure the insulation resistance of the coils.

The device works in two modes. “armature” and “stator”. Switching between modes is done by means of a switch. The device is equipped with a convenient tool for installing and securing the motor to be tested. It consists of two legs attached to a shaft. The feet move freely along the shaft, allowing the distance between them to be varied, so that different sized motors can be checked. Checked with two feeler gauges. Indication of open or short circuit in the stator winding is made by special red LEDs and a sound signal. Please refer to the instruction manual of the device for details.

It is relatively easy to check the stator of an angle grinder thoroughly. But this can only be done with special appliances. Therefore, if visual inspection confirmed that the cause of angular grinder failure is a damaged stator, further inspection and repair is better to perform in a specialized workshop.

Possible causes

Factors that cause the stator to malfunction

Signs from which you can tell that the stator is defective:

• There is a smell of burning insulation.
• The case overheats.
• Smoke appears.
• The shaft rotation slows down or stops.
• The shaft unwinds automatically, the tool rapidly reaches full speed.

Wires of the winding are covered with a protective layer of insulating varnish. Overheating causes the insulation to burn and deteriorate. This causes a short circuit on the coils. The lacquer gives off a specific smell. Short-circuiting just one of the wires completely puts the angle grinder out of action.

Rules that will help avoid overheating the motor angle grinder:

• Turn off the unit after working at lower speeds, not immediately, but after about one minute.
• Take frequent breaks when working under load at lower speeds.

It is often possible to avoid replacing a faulty stator by rewinding its winding. Rewinding a damaged angle grinder stator coil can be done with your own hands, but it is still recommended to have this work done by a specialist.

How to correctly diagnose a defective Makita rotor stator and find the right brushes

All power tools start to malfunction over time. Malfunctions are divided into mechanical and electronic. uncommon electronic malfunctions. are faults related to brush failures. In second place: failure of the armature bearings. Stator or rotor failure is less frequent. How to correctly troubleshoot the stator, rotor perorator Makita two thousand four hundred 50 and 2070, change the brushes? And here the principle diagram of the Makita 2450, 2470 peorator will help us.

How to repair or replace the brushes perorator Makita two thousand four hundred and fifty and 2470

That you need to change the brushes peoratora, lightning overpowering sparking in the area of the rotor header, the smell of burning, heating brush holders. A new or repaired peorator has a spark under the brushes is moderate, of unchanged length and no spark breakage in the circle. Bearing wear, rotor or stator insulation damage indicates clearly the spark across the entire collector circumference. Occurrence of such a spark indicates burnout of the collector plates, failure of the rotor or stator.

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How to check the stator of an angle grinder. causes of failure, inspection tools

The stator is the stationary part of the electric motor, designed to create the electromagnetic field in which the rotor (the moving part of the motor) rotates. Among the possible causes of malfunction of angle grinders, is a breakage or short circuit of the coil winding (coil) of the stator.

Possible causes

Factors contributing to stator failure:

Signs by which you can tell if the stator is faulty

• The stator begins to smell like it is burning.
• The housing overheats.
• Smoke appears.
• Shaft rotation slows down or stops.
• The shaft spontaneously unwinds, the tool sharply picks up maximum speed.

The winding wires are covered with a protective layer of insulating varnish. Overheating causes the insulation to burn and break down. This causes a short circuit in the coils. Varnish gives off a peculiar odor. A short circuit in just one of the wires completely puts the angle grinder out of commission.

Rules that will help avoid overheating of the angle grinder motor:

• Turn off the device after working at lower speeds, not immediately, but after about one minute.
• Take frequent breaks when working under load at reduced speed.

It is often possible to avoid replacing a faulty stator by rewinding it. Rewind a damaged stator coil angle grinder stator can do with their own hands, but it is recommended to entrust this work to a specialist.

Disassembling the angle grinder

How to check the stator of an angle grinder (angle grinder)? Start with the disassembly of the device. You will need a screwdriver to do the job.

• Remove all unnecessary parts from the surface where the angle grinder is to be disassembled.
• Remove the blade.
• Remove the screw that secures the hood.
• Remove the screws that secure the plate.
• Slide the hood to the side of the cord.

The stator is on the outside of the motor, on top of the rotor. To get the stator you must first remove the brushes, then remove the gearbox and only after that pull the armature from the angle grinder housing. The rotor must be taken out of the stator before checking.

Visually inspect the clutch in bright light. First of all, it is necessary to carefully inspect the coil and make sure that there are no visible tears on it.

If the inspection does not reveal the cause of the malfunction of the stator, you will need a special device to check.

Short circuit indicator test

A winding breakage or short-circuit in the winding can be detected with the short-circuit indicator (IC). Other names. indicator of inter-turn short circuits or indicator of defects in the windings of electrical machines.

• power supply;
• housing with an LCD display, sockets for connecting accessories;
• connecting wires;
• a large inductive sensor;
• Small inductive probe.

The principle of operation of the indicator is based on the induction of pulse electromotive force in the tested winding. If shorted turns are present, the magnetic field pulse from the short-circuit current flowing through them is recorded.

How to check the stator of the angle grinder with the IDVI device:

• Inspect the indicator for inter-turn short circuit. Check up if there is no any external damages, integrity of connecting wires and sensors.
• Connect the power supply.
• Press the power button and check that the appliance is in working order.
• If the indicator of winding defects was left in the cold for a long time, keep it at room temperature for at least 2 hours.
• Switch off the power supply to the angle grinder.
• Choose the big or small one depending on the stator size.
• If the angle grinder‘s data sheet does not specify the rated voltage per coil of the winding, it must be determined using the formula: The rated voltage of the entire coil divided by the number of turns.
• Switch on the unit.
• Set the amplitude of the impulse test voltage on the indicator to be higher than that received during the calculation.
• Pressing the sensor against the surface of the winding, check all the slots one after the other, waiting 3-4 seconds at a time. When a short circuit is detected, the device will beep and the corresponding inscription will appear on the display.
• If no short-circuited turns are found, then set the next (higher value) amplitude on the instrument and make sure that there is a safety margin of insulation of the winding.
• Switch off the unit.

With the winding fault indicator you can check the insulation condition between the stator and rotor coils as well as between the stator coil and the angle grinder housing. If it is not possible to buy a ready-made device, you can make a simpler indicator of short circuits yourself.

Checking with a multimeter

You can use a multimeter to check if the stator is in good working order. This is a universal measuring device. With it you can measure several electrical quantities: voltage, current, resistance.

The unit consists of a housing with a display, switch and sockets and two cords with probes (plus and minus).

always connect the minus probe to the bottom socket and the plus probe to the middle or top socket, depending on the current to be tested.

To check the stator of an angle grinder (angle grinder), it is necessary to set the multimeter to the value of resistance from 20 to 200 ohms and alternately bring the feelers of the measuring device to the windings. If the resistance is the same everywhere, the coil is fine.

If the device shows a different resistance at some points, the coil is short-circuited or one of the coils is broken. Use an ohmmeter to test the stator in the same way.

It differs from the multimeter only in the fact that this device can only measure the resistance.

Analyser for checking armatures and stators of electric machines

Yet another device you can use to check the stator of an angle grinder is the PUNS 5 machine armature and stator checker. The device has a light and sound alarm, allows you to detect winding short circuit, breakage, measure the insulation resistance of the coils.

Angle grinder preventive maintenance

Preventive maintenance of the angle grinder includes the observance of the certification requirements during its operation, periodic maintenance and scheduled repairs. First of all, it is necessary to strictly observe the ratio of work cycles and breaks recommended by the manufacturer. It is also necessary to periodically clean the inside of the angle grinder housing from dust, timely change brushes and perform lubrication of the gearbox. In the event of persistent vibrations and abnormal sounds during operation of the angle grinder, immediately carry out an internal inspection of the mechanical part and carry out the necessary repairs.

In contrast to the usual quick-clamping nut angle grinder is quite an expensive device. And how long can it last and is it possible to repair it in case of failure? If anyone knows the answer to this question, please share the information in the Комментарии и мнения владельцев.