How to check the generator contact rings by multimeter. How to check the car generator multimeter

Thus, the testing of the generator for performance does not constitute a great difficulty. The main thing is to understand the essence of the processes occurring in the device. Principal problems that happen to the generator are simple and standard. Armed with a multimeter and knowledge gained, you can easily find a malfunction in the generator.

Watch how to check the generator by a multimeter, on video

The main source of power in the car is the generator, it represents such a "mini-power station". Incorrect or unstable work This node is fraught bad (AKB). The resulting generator does not provide charging, therefore, the onboard network of the machine will work on the acb of which is not enough for a long time. As a result - the battery is completely discharged, the engine "stalls" somewhere outside the city, and you have a new "headache" and the need to replace the generator.

In order to prevent such a scenario, it is necessary to regularly monitor the state of this device, as well as the charging that it gives. If you notice any interruptions in your work, you need to check the generator, and how to do it now you will learn.

But before this I consider it necessary to talk about the precautionary measures and certain rules that need to be observed when checking this electrical appliance in order not to damage it.

!!! It is impossible:

• Check the operation of the generator by short circuit, that is, "on the spark".
• Connect the terminal "30" (in some cases "B +") with "mass" or terminal 67 (in some cases "D +").
• To allow the operation of the generator without the included consumers, especially undesirable operation when the battery is disabled.
• Perform the welding works of the car body with connected wires of the generator and battery.

• !!! Important:
• Check is performed using a voltmeter or ammeter.
• Value check is made voltage not higher than 12 V.
• In the case of replacing the wiring of the electric generator, it is necessary to select the wires of the same cross section and length.
• Before checking the device, make sure that all connections and proper tension drive belt. The belt is correctly stretched, which, when pressed for a middle with an effort of 10 kg / s, begged for no more than 10-15 mm.

How to check the generator multimeter or voltmeter?

Check voltage regulator

1. In order to check the voltage regulator, a voltmeter is required with a scale from 0 to 15 V. Before checking, you should warm the engine for 15 minutes on medium turns with the headlights.
2. Clean the voltage between the outputs of the "mass" of the generator and "30" ("B +"). The voltmeter should show a normal voltage for a particular car. For example, for the VAZ 2108 it will correspond - 13.5-14.6 V. If the voltage is lower or higher - most likely the regulator requires replacement.
3. In addition, you can check the adjustable voltage, for this, connect the voltmeter to the terminals. It should be noted that the result of such a measurement will be inaccurate if you are sure that the wiring is 100% proper. The motor has to work on medium turnover of close to the headlights and other electricity consumers. The voltage size must coincide with a certain value for specific model Auto.

Checking the diode generator bridge

1. Turn on the voltmeter into the AC measurement mode and connect it to the "mass" and the climb "30" ("B +"). The voltage must be no more than 0.5 V, otherwise there is a probability of malfunction of diodes.
2. To test the breakdown on the "mass", you need to turn off the battery, as well as remove the generator wire, which goes to the terminal "30" ("B +").
3. After connecting the device between the "30" terminal ("in +") and the disconnected of the generator wire. If the discharge current device exceeds 0.5 mA, it can be assumed that there is a breakdown of diodes or isolation of the windings of the generator diodes.
4. The capacity of the recoil is checked using a special probe, which is an addition to the multimeter. It represents something on the semblance of clamping or ticks, which covers the wires, measuring the current strength that passes through the wire.

Verification current return

1. To measure the return current, you need to cover the wire with the probe, which goes to the "30" clamp ("B +").
2. Then, boot the engine and measure, during measurement the motor should work on high revolutions. Turn on the electrical appliances in turn and measure for each consumer separately.
3. Then count the readings.
4. The following test must be carried out with all the simultaneously included consumers of energy. The value of the measurement should not be lower than the amount of the readings of each of the consumer, when you measured each of them in turn, the discrepancy is allowed to be 5 A in a smaller side.

Checking the generator excitation current

1. To check the excitation current of the generator, boot the motor and give it high speed.
2. Position the measuring probe around the wire connected to terminal 67 ("D +"), the testimony on the device will correspond to the magnitude of the excitation current, on a good electric generator it will be equal to 3-7 A.

To check the excitation windings, you will need to remove the scanner and voltage regulator. It may be necessary to clean the contact rings, also check if there are no cliffs in the winding or closures on the "mass".

- This is an integral element of each car. In this article, you will read about such a part of the generator as an anchor, the causes of its malfunction, and learn how to check the anchor of the generator.

What is the anchor of the generator?

The generator anchor includes the following parts:

Excitation winding with a pole system;

Magnetic circuit, or anchor core

Collector

The magnetic pipe consists of electrical steel sheets, the thickness of which is 0.5 mm. It is inserted on the shaft, and if the diameter of the anchor is too large, then on the cylindrical sleeve. The collector includes a number of copper collector plates from each other. They collect it separately, and then complete the insulating sleeve on the shaft.

The winding is made in the form of individual sections, the endings of which are soldered into special protrusions of collective plates. Using the reservoir, the winding section is connected to each other sequentially, creating a closed circuit. There are loop and wave winding anchors. In the loop windings, sections conclusions are attached to a number of collector plates, and the sections are connected to each other on the collector. In the wave windings, the conclusions of the sections are connected to the collector, and the sections are connected to each other as if waving. The number of collector plates is equal to the number of winding sections.

How does an anchor rotate?

The rotation of the generator anchor in the airspace between the poles occurs with the help of bearing shields and the bearings planned on the shaft. The bearing shield located on the side of the collector is called front. In the middle of the rear bearing shield and core on the anchor shaft, the fan winner is installed. It is necessary for cooling the generator. For the inflow of fresh air and removal of heat in bearing shields there are holes. They are closed with protective covers with a grid. Holes located in the front bearing shield are also needed to maintain a collector and brush node.

Anchor generator, DC network and pole windings are connected using brushes. These brushes are on the belt holders, and they, in turn, are fixed on special fingers. Fingers are fixed on the traverse, which is attached to the front bearing shield or to the bed. In the belt holders, you can adjust the pressure of the brushes to the collector using springs.

The number of brush fingers is equal to the number of poles. At one half of the poles positive polarity, the other is negative. Brush half of one polarity is interconnected by niches. The brush node divides the generator anchor winding into a number of parallel branches, the number of which depends on the type of winding.

The total electric network of the car and the generator are interconnected by the box of the conclusions in which the terminal board is located with the labels of the output of the available windings. For lifting and moving the generator on top of the beds, a ry-bolt is installed. The manufacturer's plate is fixed on the bed housing. It shows the winding information and the main characteristics of the generator.

The significant disadvantage of DC generators is relatively high complexity and insufficient strength of the brush-collector assembly in need of permanent maintenance. The generated current in anchor of a powerful generator is very high and cannot be removed from the brushes. Remove it from fixed coils. Because of this, there is a stator in powerful generators instead of anchor, and instead of the inductor - the rotor.

The most common breakdowns of the generator anchor

The most common breakdowns of the generator anchor:

Wear of contact rings;

Breakdown of the shaft bearing;

Short winding closure.

Defects that are not subject to repair: wear collector to a diameter of 86 mm; Wearing the keypads more permissible, if the groove has already been previously expanded, and the thread breaks more than 2 threads on the end of the shaft.

Generator Anchor Checking

First you need to conduct an external inspection of the generator anchor. In the absence of flaws, with an external inspection, you can proceed to the internal. First you need to check the winding on the quality of isolation between the turns, and even between the winding and mass. When checking, you need to use the tester or the control light. It is connected to the usual industrial network of alternating current with a voltage of 220 V. One wire from the check light is attached to the shaft of the anchor, and the second in turn is triggered to the collector plates. There should be safe insulated tips on the wires. If there is a closure of the winding of the anchor on the "mass", the control lamp will light up.

To check the inter-touch closure, an induction device is used (Fig. 1). The core of the device is made of transformer iron. Power The coil occurs due to industrial alternating current. The generator anchor is put in the prism of the core and, rotating around the axis, the metal plate is attached to its gland.

If there are no intersensile closures, induced in the anchor winding electromotive force balanced, and, therefore, there will be no current in the winding. In the case of the presence of the intersensive closure, the electromotive force in short-circuited turns is induced. The excited alternating current forms another alternating magnetic field on the area with short-circuited turns. If this field is available, there is a certain vibration of a metal plate attached to the anchor gland. Vibration plate indicates the presence of short-circuited turns. Anchors that have this defect to be rewound. And the anchors whose windings are working, are subject to the following check.

1 - appliance core; 2 - coil; 3 - Metal Plate

Fig.1. Scheme of induction device

Repair anchor generator

The extension surface of the shaft of the generator anchor under ball bearings is repaired by plastic deformation (rolling). Anchor put in centers turning machine, and worn necks are treated with a pump at a step, equal to 1-1.5 mm. The diameter of the neck becomes larger at the expense of a metal that swallows from the created depression. At the end of this processing, the necks are grinding to the desired size. Before grinding, the shaft and correction of the centers will be carried out. If keystalls were worn out, that is, more permissible parameters, then milling new grooves at an angle of 180 ° in relation to the old one.

Requirements for a repaired shaft: The beating of the shaft sock during inspection in prisms with respect to the necks can not be greater than 0.05 mm; Iron beating Anchor can be up to 0.05 mm; The sparkled shaft can be corrected by the press. In the event that the size of the fusion of iron anchor is greater than permissible parameters, iron anchors need to be sharpened before the repair diameter.

The worn collector is repaired before eliminating defects; The collector diameters should not be less than 86 mm for the generator. After the collector crawled, you need to cut through the mikanite insulation among the plates to a depth of 0.8 mm; The width of one groove should be 0.6 mm. To cut through the insulation, use a desktop horizontal milling machine and a six-sided disk mill, the diameter of which is 12mm. The mill is not treated with grinding and sharpening, but applied to process 5-6 collectors. At the end of the insulation milling, the collector is very well polished with a small grain sandpaper, and then blown with dry air to remove the mikanite and copper dust.

Iron anchors need to be painted with nitroglyphthalic varnish, and the winding is covered with insulating varnish. After that, put them dry into the drying cabinet with a temperature of 110-120 ° about ten o'clock. Restored anchor must be checked for closing the winding between the turns and on the body.

The car generator is the main source of energy in the on-board network and when it or fails, you will not drive for a long time on the same battery. That is why it is so important to control the operation of the generator.

The full range of generator checks includes:

In most cases, it is not difficult to check the car generator with your own hands, because on what kind of car you did not check, the principle is the same. But still, many car owners are often wondering: how to check the generator by a multimeter or undergraduate means?

How to check the generator without removing the car

There are two ways using a multimeter and without it. The first, relatively new, is that, and the second, old and verified, almost in the opposite - the battery terminal must be removed on the engine running.

1. Verification of the battery multimeter first occurs at rest - the voltage must be within 12.5-12.8 V. Then you need to measure the testimony already on launched engineIf 13.5-14.5 is observed at 2 thousand turns, it means everything is in order. With that on new cars even 14.8 in quite normal, as manufacturers assure - the abundance of electronics affects. In conclusion remains check voltage under load, that is, connecting consumers - stove, headlights, heated, radio. Failing within 13.7-14.0 V is considered to be permissible, but 12.8-13 in already talk about a malfunction.
2. The second way, like many "grandfathers", simple and trouble-free, but at the same time rather dangerous and requiring accuracy. According to statements, it works both on vases and on relatively new cars, like Aveo. What is the essence - weaken the bolt of fastening the minus terminal of the AKB key to 10, start the engine and give a small load by turning on one of the consumers, such as headlights. Then remove the terminal when the motor running is if it does not stares and the headlights are not a meal, it means that everything is fine with the generator, otherwise you can be sure that it is broken. Trying such a method should be at your own risk.

It is extremely unwittingly to allow the operation of the generator with the disconnected consumers, especially the battery. This can lead to a relay controller malfunction.

Finding out that there is a malfunction, you should dismantle and check the removed generator with a multimeter, a light bulb and visually. The check is subject to each of its elements separately.

First of all, it is worth making sure that the generator belt is well stretched, and the bearings are not broken. Foreign noises and a very hot generator talk about wear of bearings.

How to check brushes and contact rings

For the start of the ring and the brushes visually inspect, and their condition is estimated. For example, the minimum residue is measured (min. the height of the current-piece brushes do not 4.5 mm, and min. Rings diameter 12.8 mm). In addition, they look at the presence of workings and furrows.

Brushes extracted from the brush knot of the regulator

Generator Rotor Contact Rings

How to check the diode bridge (rectifier)

Checking the diodes is made by measuring resistance and detection of conductivity. Since the diode bridge consists of two plates, then check one immediately and then another. The tester should show the conductivity of diodes is only in one direction. Now a little more details: one tester probe is kept on the "+" terminal, and then alternately check the conclusions of the diodes, and then change the probe (in one case there should be great resistance, and there is no other). Then we act in the same way and with another part of the bridge.

It should be noted that the resistance should not be zero, as it says that the diode is punched. The punched diode of the bridge and then when there is no resistance in both sides.

Checking a diode bridge

Checking contact rings

At least one the unsuitable diode leads to the failure of the entire diode bridge And gives an abbance of the battery.

Checking the generator may be required when sunbathing the battery charge lamp on the instrument panel, and this means that the battery is charging. Each driver is useful to know how to check the generator and its details that will be described in detail in this article.

No charge rechargeable battery It can occur not only by the fault of the generator, and for example, due to the failure of the regulator relay. And before checking the generator, you should first make sure that the regulator relay is good.

How to check the regulator relay different types I wrote in detail here in. And about the generator device and its main faults can be read. The generator and the serviceability of its some parts can be checked without the generator disassembly or disassembly and the methods of verification will be described below.

If, when checking, some of the malfunction of the generator will be detected, it will be possible to eliminate them as described here in, about the repair of the generator.

Check generator in parts.

Stator check Generator. The generator stator is checked separately after generator disassembly. All conclusions of the stator must be disconnected from the diodes (valves) of the rectifier block.

First, you visually make sure that the lacquer of the stator winding wires has no traces of overheating (and even more so melting), which can occur with a short closure in the rectifier valves. The stator with traces of melting isolation should be replaced.

Checking the generator using the stand .

Checking on the stand allows you to most accurately determine the operation of the generator and the correspondence of its characteristics nominal. To assemble the stand, you will need to fix the electric motor with a plug on the welded frame from angle (or profile tube), then fasten the generator on the same frame so that the pulley of the electric motor rotates the pulley of the generator using the belt.

Reostat 4 will still need (see the connection circuit on the left) Voltmeter 3, the control 12-volt light bulb (3 W) 1, ammeter 5, switch 6, and automotive 7 (the generator itself is 2 in the figure). Everything connects according to the scheme in the figure.

Before checking the generator, it is necessary to clean the contact rings of the generator from the tax, and the brushes must be well sorted in shape to the contact rings. After connecting all the components of the stand according to the figure, turn on the electric motor and the retail 4 set at the output of the generator voltage equal to 13 volts. Then brought the rotor of the generator rotor to 5000 rpm.

With such revolutions, we give the generator at least two minutes, then measure the strength of the recoil current. A serviceable generator of front-wheel drive vases (VAZ 2108 - 09) The current will be at least 55 amps. Have more powerful generators of foreign cars the rate of current returns more, and how many exactly ampen - this can be clarified in specifications Specific generator.

1 - Generator, 2 - Voltmeter, 3 - Control Light Bulb, 4 - Reostat, 5 - Ammeter, 6 Switch, 7 - Battery.

The walls for checking generators of foreign cars are almost the same, only the findings of imported generators have other notation (D and B +), as in the figure just above.

If it turns out that the current is less than laid, this indicates the faults in the winding of the stator or the generator rotor, or the damage to the diodes, or the wear of the contact rings or brushes. In this case, the disassembly and testing of windings and diodes will be checked, as described above.

Checking the voltage at the output of the generator is checked during rotor revolutions 5000 rpm. In this case, we set the recoil current of 15 amps and measure the voltage at the generator output. It must be 14.1 ± 0.5 volts, at a temperature of 25 ± 10 ° indoors where the stand is located.

If the voltage has a different value (less or more than 14.1 ± 0.5 volts), then the regulator should be replaced with a new or obvious and re-repeat check. If the replacement of the relay does not help and the voltage will still differ from the norm, it means that the regulator is not in the relay, but in the windings of the stator or rotor, or in the faulty diodes of the rectifier block.

Checking the generator using an electronic oscilloscope .

The electronic oscilloscope is not far from all, but it allows the shape of a rectified voltage curve quickly and accurately check the operation of the generator and determine the nature of the damage. Therefore, it makes sense to write this method of checking the generator.

To check the scheme should be collected as shown in the picture on the left. Then, disconnect the total output wire of three additional diodes from the terminal in the voltage regulator relay and wind the tip of the disconnected wire with a tape (so that it does not corner on the generator body).

Next, to the terminal in connect the wire from the battery (see Figure) through the control light 1. Now the excitation winding will be powered only from the battery. Include the electric motor of the stand and we achieve the rotor of the generator rotor approximately 1500 - 2000 rpm. Then the switch 6 turn off the battery from the generator terminal 30 and with the help of the 4 amp of the recoil current.

We check the voltage on the oscilloscope on the generator terminal 30. With good rectifier diodes and a serviceable stator winding, the straightened voltage curve has the shape of the uniform teeth of the saw as in Figure A (see Figure just below).

A - generator is good.
B - Diode breaks.
B is a break in the diode chain or in the stator winding.

If there is a break or short circuit in the rectifier diodes or a break in the stator winding, then the curve form will be with uneven teeth with deep depressions (see Figure B and B).

When the terminal 30 was checked and made sure that the curve shape is normal, you should check the voltage on the plug 61 or on the tip of the wire, which is disconnected from the plug in the regulator relay. These points are a common output of three additional diodes that feed the excitation winding during the operation of the generator.

And here the shape of the voltage curve should have the right shape of the teeth. If the shape of the curve has an irregular shape of the teeth, then this indicates the failure of additional diodes.

More about checking and restoring the generator and the relay of the foreign car regulator can be read.

Well, finally, several warnings that are important to know each driver.

• The minus wire from the battery should always be connected with a mass, and the plus wire is connected to the generator terminal 30. Reverse (erroneous) Connecting the battery instantly causes the increased current through the diodes of the generator rectifier and the diodes will fail.
• You can not allow the operation of the generator with a disconnected battery, as it causes the occurrence of short-term overvoltages on the terminal 30 of the generator and it will damage the voltage regulator and others electronic devices Onboard network of a modern car.
• It is strictly forbidden to check the health of the generator on the spark, even a short-term connection of the terminal 30 of the generator with a mass. At the same time, a high current flows through the diodes of the rectifier block and they fail. You can check the operation of the generator only with a voltmeter and ammeter.
• The generator rectifier diodes cannot be checked by a megommeter (it is too large for voltage diodes) or voltage of more than 12 volts. Since the diodes are punched with such an inspection (a short circuit occurs).
• It is also prohibited to check the wiring of the machine with a megommeter or lamp, powered by voltage of more than 12 volts. If such wiring is necessary, you should pre-disconnect the wires from the generator terminals.
• Checking the insulation resistance of the generator generator winding with increased voltage can only be on the stand, but necessarily with the phase windings disconnected from the rectifier.
• For body work Using electric welding, it is necessary to disconnect the wires from all terminals of the generator and battery.

That's it seems to be all. Of course, the generator check is not such a simple matter, but with a competent approach and the availability of appropriate knowledge, it is quite possible to identify any malfunction and eliminate it without the help of an autoelectrician, success.