How to connect an analog ammeter. How to connect an electronic ammeter to a charger

We all know that an ammeter is a device for measuring current, which is measured in amperes. It measures amperes, which means an ammeter.

But, in order to measure the current, it is necessary to correctly connect the ammeter to the circuit. Whether it is a permanent circuit or alternating current... After all, incorrect switching on of the device can lead to its failure.

The ammeter is connected to the electrical circuit in series

That is, we have a wire, an electric current flows through it from the source of this very current to the consumer, which can be an electrical device.

To measure the current with an ammeter, we need to de-energize (disconnect) the power supply. Then you need to break the chain - literally and figuratively. Roughly speaking, cut the wire.

We now have two wires. We take an ammeter, connect two halves of the cut wire to the device. It is necessary to take into account the fact that the current flowing in the circuit must be less than the maximum measured current of the device. The maximum measured current of the device must be written on the device itself or in the documentation for it.

After the wires are connected and securely fixed in the ammeter, you can turn on the power and the device will show the amount of current in the circuit, which will pass through the ammeter.

But no one does this, because the cut wires do not lead to good.

The ammeter has a small internal resistance, this is done so that it has a minimum effect on the magnitude of the measured current. When connecting an ammeter to an alternating current circuit, it does not matter where to connect the device.

When connecting the ammeter to the circuit direct current, if the arrow deviates in the other direction, or if it shows zero, you should change the polarity, swap the wires.

Connecting an ammeter through a shunt

If the current in the circuit turns out to be greater than the current of the device, then a shunt can be calculated and used to measure the current of a larger value. In this case, the chain will split into two branches. One will have a small resistance of the ammeter, and the second will have a large resistance of the selected shunt. The large current will be divided in proportion to the resistances and a small current will pass through the ammeter, and a large one through the shunt. ().

Current measurement with an ammeter through a current transformer or clamp meter

There are times when you need to measure the current in a cable, on a bus ... an insulated bus. A tire is a strip of a certain section through which a current flows, not a car wheel ...

Cutting a cable or bus can be costly and pointless. In this case, you can use a clamp meter or a current transformer.

The current transformer has two windings - the highest and the lowest, which are not interconnected. The current comes to the highest one, then an EMF () is created and a current flows in the secondary winding proportional to the number of turns of the windings. So, if there is a need to measure the current, then a "donut" is hung on the cable, it is also a TT. And already. The main thing here is to be properly instructed and not to get things done. It turns out that we remove the current with an ammeter from the secondary winding, converted to the lower side and safe for measurement and ammeter.

The same principle is used in the measuring clamp, only the ammeter and the CT are in the same case. And on top of that, the primary winding of the tongs is opened at the touch of a button on the case and then closed.

Catalog number: 3811010-AP111B

Specifications Ammeter Ap-111

Applicability

Tractors T-150 K, 158, DT-175S, 75 U, T-130 MG, PAZ-672, GAZ-71, 66-01, UAZ-469РХ, URAL-479

Ammeter Installation

On most vehicles, only the charge indicator lamp is used to monitor the operation of the power supply system, which does not monitor the status battery, the charging current, the voltage in the on-board network and, in addition, does not allow the determination of a number of faults in the circuits. Full information the operation of the generator and the battery can be obtained by equipping the car ammeter and a voltmeter.

Ammeter usually connected to a break in the wire going from the generator to the battery. For example, on VAZ cars between the terminals "B +" of the generator and "+" of the storage battery. Connection Ammeter must be made with a wire of a suitable cross-section. For example ammeter AP-111 it is necessary to connect with a wire with a cross section of at least 20kV, otherwise the wire will heat up. Myself Ammeter during operation, it may also heat up a little, because a shunt is installed inside it, on which, with a large current, heat is also generated, this is not a malfunction.

It is much easier to connect a voltmeter, wherever there is a "+". Accordingly, one contact is connected to the body, the other is more convenient to connect to the terminal of the ignition lock where "+" appears when the ignition is turned on. The figure shows a typical connection diagram Ammeter and voltmeter

Ammeter connection diagram and voltmeter:

1 - rechargeable battery

2 - generator

3 - mounting block

4 - ignition switch

5 - a control lamp of a charge of the storage battery, located in a combination of devices

6 - ammeter

Car drivers and trucks interested in how to connect an ammeter and voltmeter in the car. The need to install these indicators is due to the desire to have complete control over the condition of the battery and generator set. Most modern cars and previously released ones do not have such indicators installed by the manufacturer. True, in cars with on-board computers, it is possible to control the voltage in the circuits of the car, in other models the owners are engaged in installing the devices.

How to connect an ammeter and voltmeter in a car it is especially interesting for owners of used cars, since many components and assemblies, including the generator set, are already worn out, so they can work with violations. The control lamp signals only about the absence of on-board voltage, and this is clearly not enough. So, for example, if you do not notice the increased charging voltage of the battery in time, this can lead to its failure.

About the functions of these pointers

Each control or measuring device installed in the dashboard of the car informs the driver about the operability of a certain system of the car. This allows you to operate the machine without prejudice to its technical condition. However, the power supply system of many cars is deprived of the possibility of such control. Car owners try to solve such problems on their own by installing an ammeter or voltmeter, and some owners install both of these indicators.

An ammeter installed in the electrical circuit will indicate the electrical current consumed by the system. Based on these data, you can judge the battery charging process and timely identify and eliminate the problems that have arisen. The voltmeter also allows you to keep this process under the control of the driver, which increases the life of the electrical equipment. Here are the main reasons for installing these devices on a car.

What products are used?

Some time ago, finding and installing such a device was a big problem. Car enthusiasts installed ammeters from trucks on their cars, and those drivers who were on board with radio electronics selected measuring instruments themselves. The first domestic cars, in which the voltmeter took its permanent place on the dashboard, was the VAZ 2105, and a little later they appeared on other models.

Today, such a problem does not exist, since there is a large selection of such products in retail chains. Can be installed in a panel Digital Watch which simultaneously with current time show the voltage of the on-board network. There are electronic tachometers that, after pressing desired button perform the functions of a voltmeter. Such devices do not cause any particular problems for the owners.

Also today, car ammeters and voltmeters are on sale, and individual drivers independently adjust the devices that are used in electronic devices. The installation of such indicators is fraught with some difficulties, since it is necessary to select shunts for them, to calibrate or manufacture new scales. Therefore, we will not dwell on this.

How to install such indicators? We will assume that you managed to purchase an ammeter or voltmeter intended for use in cars, now we will consider the process of installing them. It should be recalled the peculiarities of connecting them to electrical circuits.

The ammeter is connected only in series between the current source and consumers, while the polarity of the connection must be observed, plus from the source to the plus of the device, and so on. The voltmeter is connected only in parallel to the power source, also observing the polarity.

We connect the ammeter

To begin with, work can only be started after disconnecting the battery. A significant current flows through this device, so you need to select wires of the appropriate cross section. It should be connected to a break in the wire that supplies power to the ignition switch. On the ends of the wires, you should install and crimp the terminals with pliers, otherwise, due to bad contact the connection point will heat up.

After installing the wires, check that the connection is correct. To do this, turn on the load, for example low or high beam. The ammeter should show a discharge, if it shows the opposite value, then the connection wires should be changed. Next, start the engine and make sure that the battery is charging.

Everyone should know the rules of how to connect an ammeter. So, for example, such knowledge is often used in drawing up tasks for experimental rounds of school Olympiads or laboratory work.

Let's start with the principle of the ammeter. The fact that it measures amperage is obvious simply from the name. It happens as follows: an electric current moving along the circuit also passes through the device. In this case, a torque is created, which becomes the cause of the deflection of the dynamic (movable) part by a certain angle. This deviation is directly proportional to the amperage. Further, this is displayed visually, for example, by moving an arrow or displaying a number.

Let's remember the concepts of parallel and serial connection. If you need to measure the current strength on some receiver, then its value must coincide with what passes through the ammeter. This is specific for a serial connection.

However, the connection method is not the only important condition for how to connect the ammeter. The resistance of the ammeter is of no less importance. If it suddenly turns out to be higher than the resistance of the receiver, when the device is connected, the system of the circuit will be disrupted, and the value of the current acting on the receiver will change.

When connecting to a gap, it does not matter whether to connect with the "plus" to the power source or the device. The main thing is to be consistent, not parallel.

There are several types of ammeters. Among them are analog and digital. With the help you can measure both direct and alternating current. However, for any of them, the rules for connecting the ammeter remain unchanged. One has only to check what current is measured by a particular device. This is indicated on the device itself. If the current is constant, "=" is indicated, if the variable is "~". This must be done without fail, otherwise the ammeter will not work.

In addition, safety rules must be followed when working with electricity. If you come into contact with bare wires and carelessly, there is a chance, if you get a non-electrical burn, then very unpleasant sensations. This is especially true for real installations, because in a school laboratory, as a rule, the circuit is powered by a battery, and the current is not too high.

Thus, a characteristic feature of the ammeter is its serial connection. This limits the number of ways to connect an ammeter.

Very often, novice radio amateurs ask the same question: - How to connect a universal Chinese voltmeter ammeter to a homemade charger or a regulated power supply? V Lately I am literally inundated with questions, how to connect, where to connect. Therefore, I decided to write a specially separate article in which I will tell you in detail how and how to connect a Chinese voltmeter ammeter to a charger or a homemade regulated power supply.

Today there are two popular Chinese, universal models of voltmeters ammeters with a built-in shunt, which all beginners and professional radio amateurs, without exception, love to buy in China on Aliexpress.

Let's take a closer look at two models of the most popular Chinese-made voltmeters and ammeters.

Both devices have five wires for connecting to the power supply. The first one on the left has three thick wires (black, blue, red) and two thin (black, red). Thin wires are designed to power the device: red plus, black minus. Thick wires: Black minus ammeter, blue ammeter output, red voltmeter input.

The second device also has five wires, three thin (black, red, yellow) and two thick wires (black, red). Thin wires are designed to power the device: red plus, black minus, yellow input of the voltmeter. Thick wires: black minus ammeter, red ammeter output.

Every Chinese universal measuring device (CUIP) has a built-in measuring shunt for an ammeter, and this is a big plus, because there is no need to "farm" anything, it is done according to the "set and forget" principle. In some KUIPs, the shunt is curved with the letter "M" and shiny, I got copies with a copper "P" shaped shunt. As I understand it, the shape and color of the shunt does not affect the quality of measurements.

The devices on the board have trimmer SMD resistors with which it is possible to correct the readings of the voltmeter and ammeter.

This figure shows a diagram of connecting a voltmeter of an ammeter of the first model to a charger from computer unit nutrition.

The device is powered from a separate power source in in this case This is a five volt phone charger that can be easily placed in the power supply case. The fact is that if you connect a voltmeter-ammeter to the regulated output of the power supply, then when the voltage drops below 4.5V, the device will simply stop working. The fan speed will also decrease, but at low voltage the radiators of the power supply unit will be a little warm and nothing terrible will happen.

With an output voltage of more than 12V, the L7812CV voltage stabilizer is turned on and thereby maintains a constant voltage on the fan of no more than 12V.

This figure shows a diagram of connecting a voltmeter of an ammeter of the second model to a charger from a computer power supply.

With a charger from a computer power supply, everything is clear. Let's look at the wiring diagram of a Chinese voltmeter ammeter of the first model to an adjustable power supply. The upper part of the diagram shows a regulated power supply with protection against short circuit consisting of a diode bridge, a capacitor, an LM317 voltage regulator, an MJE13009 transistor, a variable resistor and three fixed resistors.

In the lower part of the circuit, the fan and the Chinese voltmeter ammeter are connected through the L7812CV voltage regulator to the output of the diode bridge in parallel with the capacitor C1. The stabilized voltage on the fan and control unit is not more than 12V.

This figure shows a diagram of connecting a Chinese voltmeter ammeter of the second model to an adjustable power supply.

Many radio amateurs prefer to install in chargers and adjustable blocks power supply analog Chinese measuring devices (instrumentation) for many years have not lost their popularity. Therefore, I propose to consider the connection diagram of a classic dial voltmeter and ammeter.

This figure shows a wiring diagram for a voltmeter and ammeter with a built-in current-measuring shunt.

The voltmeter is connected in parallel to the power source, observing the polarity. There should be plus and minus marks on the device. The ammeter is usually connected to the gap in the negative wire after the voltmeter. You can also connect the positive wire to the break, the method of connecting the device does not affect the accuracy of measurements. The main condition is the observance of polarity.

Sometimes there are ammeters without a built-in current-measuring shunt. Then the shunt has to be bought separately. So that you do not have additional costs, before buying an ammeter, always check with the seller for the presence of a shunt inside the device. Sometimes the cost of a separate shunt is more than the cost of a device with an integrated shunt.

This figure shows a wiring diagram for connecting a voltmeter and ammeter with a separate current-measuring shunt to the power supply.

The shunt is always connected in parallel with the ammeter. Without it, the device will simply burn out. How to choose a shunt? If the device is rated for 10A, then the shunt must be 10A. Each shunt has a mark indicating what amperage it is rated for.

Well that's all, my article has come to an end, you now have new food for thought.

Friends, I wish you good luck and good mood! See you in new articles!

A miniature Chinese voltmeter can simplify the process of measuring the voltage and the amount of current consumed on a power supply or homemade charger. Its cost rarely exceeds 200 rubles, and if you order it from China through partnership programs, you can also get a tangible discount.

To the charger

Those who like to design chargers on their own will appreciate the opportunity to observe the voltages and amperes of the network, without the help of bulky portable devices. It will also appeal to those who work on expensive equipment, the operation of which can be adversely affected by a regular drop in mains voltage.

With the help of a Chinese ampere-voltmeter, which is no larger than a matchbox, you can easily monitor the condition electrical network... One of the perceptible problems faced by newcomers to electricians can be the language barrier and different wire markings from the standard one. Not everyone will immediately understand which wire to connect to, and the instructions are usually only in Chinese.

Devices for 100 V / 10 A are very popular among independent designers. It is also desirable that the device has a shunt to refine the connection process. A tangible plus this device is that it can be connected to the power supply of the charger or to a self-contained battery.

* The voltage of the power supply of the ammeter, voltmeter should be in the range from 4.5 to 30 V.

The connection diagram is as follows:

The black wire is a minus. It must also be connected to a minus.
The red wire, which should be thicker than the black one, is a plus and must be connected to the power supply accordingly.
The blue wire connects the load to the mains.

If everything was connected correctly, two scales should be highlighted on the display.

To the power supply

Power supplies play an important role, equalize the network readings to the desired state. If not properly operated, they can severely harm expensive equipment, causing overheating. In order to avoid problems during their operation, and especially in cases where the power supply is made by hand, it is advisable to use an inexpensive ammeter, voltmeter.

From China you can order the most different models, but for standard devices powered by home network suitable are those that measure current from zero to 20 A, and voltage up to 220 V. Almost all of them are small and can be installed in small power supply cases.

Most devices can be adjusted using built-in resistors. In addition, they are highly accurate, almost 99%. The scoreboard displays six positions, three for voltage and current. They can be powered either from a separate or from a built-in source.

To connect a voltmeter, you need to deal with the wires, there are five of them:

Three thin. Black minus, red plus, yellow to measure the difference.
Two fat ones. Red plus, black minus.

The first three cords are most often combined for convenience. The connection can be made through a special socket connector, or by means of soldering.

* The connection by soldering is more reliable, with slight vibrations, the socket mount of the device may come loose.

Step by step connection:

It is necessary to decide from which power source the device will operate, separate or built-in.
Black wires are connected and soldered to the minus PSU. Thus, a general minus is created.
In the same way, you need to connect the thin red and yellow contacts. They are connected to the power contact.
The remaining red contact will be connected to the electrical load.

If connected incorrectly, the instrument panel will show zero values. In order for the measurements to be as close as possible to the actual ones, the polarity of the supply contacts must be correctly observed. Only connecting the thick red wire to the load will give an acceptable result.

Note! Accurate voltage values can only be obtained from a regulated power supply. In other cases, the display will only show the voltage drop.

A popular voltmeter model that is often used by radio amateurs. Possesses the following characteristics:

Operating voltage DC 4.5 to 30 V.
Power consumption less than 20mA.
The display is two-color red and blue. Resolution 0.28 inches.
Performs measurements in the range 0 - 100 V, 0 - 10 A.
The lower limit is 0.1 V and 0.01 A.
The error is 1%.
Temperature conditions of work from -15 to 75 degrees Celsius.

Connection

Using a voltmeter, you can measure the current voltage in the power supply network. To do this, you need the following:

Connect the black thick wire to the minus of the power supply.
Red is connected to the load, and then to the power supply.

This wiring diagram does not require the use of a thin black contact.

If a third party power supply is used, the connection will be as follows:

The thick cords are connected in the same way as in the previous example.
Subtle red connects to the plus side of a third party source.
Black with a minus.
Yellow with a plus source.

This voltmeter, ammeter is also convenient in that it is implemented in an already calibrated state. But even if inaccuracies were noticed in its work, they can be corrected using two tuning resistors on the back of the device.

What are the most reliable digital voltmeters

The electrical equipment market is overflowing with manufacturers who provide a wide variety of choices. However, not every device brings positive emotions from use. For a large number of products, it is not always possible to find a reliable and inexpensive copy.

Trusted and reliable voltmeters include:

TC 1382. Inexpensive Chinese, the average price of which rarely rises above 300 rubles. Equipped with tuning resistors. Carries out measurements in the ranges 0-100 Volts, 0-10 Amperes.
YB27VA. Almost a twin of the previous voltmeter, it differs in wire marking and a reduced price.
BY42A. It is more expensive than previous models, but also has an increased upper measurement limit of 200 V.

These are the most popular representatives of this type voltmeters, which can be freely purchased for alteration on the radio market or ordered via the Internet.

Calibration of Chinese voltmeter ammeter

Over time, any technique wears out. Since the operation of measuring devices is affected not only by their own faults, but also by failures in the connected devices, sometimes it is necessary to make adjustments.

Most models have special resistors on their case. By rotating them, you can redo the zero values.

All measuring devices have a measurement error, which is indicated in the documentation.

Conclusion

The inclusion of inexpensive voltmeters in the circuit avoids problems with inappropriate mains voltage. For a small fee, you can find out if the equipment is working under the right conditions. To connect them, you need to know the marking of all wires and the location of the plus and minus of the energy source.

The word “meter” is associated with the measuring system. Current is measured in amperes. Therefore, an ammeter is a tool that measures amperage. To get correct results and not damage the device, you need to know how to connect an ammeter to an electrical circuit.

Varieties of ammeters

All devices are divided into two types: analog and digital.

Analog devices:

Magnetoelectric. A permanent magnet located in the instrument housing creates a magnetic field that interacts with magnetic field a freely moving coil while flowing over it electric current creating torque. The deflection of the arrow associated with the coil corresponds to the quantitative indicator of the current. The device is distinguished by high sensitivity and accuracy, but it is designed to control low DC currents. A shunt is installed to expand the measuring range;
Electromagnetic. They consist of an arrow attached to a magnet located inside the coil. When current flows through the coil, a magnetic field is created that attracts or repels the magnet in proportion to the magnitude of the current. Universal ammeters, which measure alternating current of industrial frequency and direct current;
Electrodynamic. They have two coils: fixed and mobile, which create magnetic fields. The reaction between these fields provides the deflecting moment of the moving system, which is compensated by spiral springs. They are used in alternating current electrical circuits operating at a frequency of 50-200 Hz and direct current;
Thermoelectric. Based on the principle that all conductors expand when heated. This expansion corresponds to the released energy, which, in turn, is proportional to the square of the current, regardless of its direction and nature. The current flows through a resistor in contact with a thermocouple connected to the needle of the ammeter. This indirect method is mainly used to measure high frequency currents;
Ferrodynamic. The principle of operation is similar to electrodynamic systems, but the moving coil is placed inside a magnetic circuit made of ferromagnetic materials, on which there are stationary coils. This creates a strong magnetic field, which increases the sensitivity of the device and its immunity to external fields.

Technological advances have provided digital ammeters with great versatility and performance. With digital instruments, reading errors are eliminated, since the readings are visualized in numbers. Since the mechanical parts are replaced electronic circuits, wear is minimized.

Important! The quality of a digital device depends on the quality of the circuits used.

Two of the most widely used handheld instruments are the multimeter and the clamp meter. They are available in analog and digital versions, but the latter are more common now. Clamp meters are very useful because they instantly measure current without breaking the circuit. These devices are controlled by a magnetic field around a current-carrying wire and have no coils to burn out.

Ways to connect an ammeter

The main feature of the device is that it must have a small resistance. This is necessary to ensure a slight voltage drop across it. For a perfect measurement, the device must have zero internal resistance, but this is unattainable. The ammeter is connected to the circuit in series, in contrast to the voltmeter. If you connect it in parallel with the power supply, the current will go in a virtually short-circuited path and can damage the device.

The ammeter connection diagram can be direct and indirect. In a direct circuit, the device is directly connected to the circuit between the power supply and the load.

The indirect scheme is implemented in two ways:

Installing the shunt parallel to the ammeter, when almost all the current is passed through the shunt, which has a small resistance, and a small part of it gets on the coil of the device. The relationship between the currents and resistances of the shunt and the device:

Ish / Ipr = Rpr / Rsh.

Thus, using calibrated shunts, you can expand the range of measured currents;

The use of instrument transformers. It is used for fixing large currents on high voltage electrical equipment. The current in the power circuits is converted by means of transformers into small quantities (usually 5 A). Measuring devices are connected to the terminals of the secondary winding.

Important! The terminals of the secondary winding are always closed to a resistor, and work in an open circuit is prohibited due to the fact that it may be under the phase voltage of the power circuit.

Shunt ammeter connection sequence

Circuits with current transformers are used in power plants. To connect ammeters in low-voltage circuits, amateur electricians, as a rule, use a circuit with shunts.

The sequence of steps for assembling the circuit:

Many ammeters are supplied with calibrated shunts. It is necessary to know the approximate range of the measuring currents. Knowing the current, the appropriate shunt is selected;
Fasten the shunt to the ammeter contact terminals;
Disconnect the current control device;
Open the power supply circuit and connect in series with the load (lamp, resistor, etc.) an ammeter with a shunt element attached to it, taking into account the polarity of the device (for analog devices) and source;
Apply voltage and remove data;
Switch off the power supply again, disconnect the ammeter and restore the normal circuit;
The value of one division of the device is determined based on the value of the current indicated on the shunt.

In the multimeter, the shunts are already built into the instrument. You just need to put the switch in the desired measurement range. This is done with the power removed.

Important! If the ammeter is included in the circuit to determine the charging current between the charger and the battery, then the "plus" of the charger is connected to the "plus" of the ammeter, and the "minus" of the ammeter with the "plus" of the battery.

Connecting a digital voltammeter

There is an interesting digital module for direct current, combining the functions of a voltmeter and an ammeter in one device. Voltammeters can simultaneously show both current and voltage when connected correctly.

An example of such a device– modelDSN– VS288, consists of:

the measuring device itself;
2-wire cable (ammeter input and output);
3-wire cable (instrument power and voltage measurement).

Measured range of ammeter:

from 0 to 100 V in voltage,
from 0 to 10 A on current.

Since the supply voltage of the device– 3.5-30 V, its switching circuit is different:

If necessary, connect the device to a circuit with a voltage between 3.5 and 30 V, general nutrition simultaneously used for the device. The black wire of the 2-wire cable goes to the minus, the red to the load and from the other load terminal to the plus. On a 3-wire cable: yellow and red - connected together at the positive source, and black - remains free;
If the voltage of the MT is greater or less than the power supply range of the device, then the voltammeter must be connected to the individual MT. A two-wire cable is connected in the same way, for a three-wire cable - red and black - go to the "plus" and "minus" of their IP, and the yellow one - to the “plus” of the main IP.

Each type of ammeter is connected according to the same principle, but with the obligatory consideration of the quantitative value of the measured current and the choice of appropriate instruments and devices for this.