How to connect an ammeter to take readings

Electric chains have become an indispensable attribute of modern life. They permeate almost everything, and people do not even think that it's worth to disappear the electric current, and our world will be subject to serious danger. What is a current, can it be measured and what will these readings give to an ordinary person?

The laws of current behavior are studied in school, and, in principle, every high school student knows about the directed motion of charged particles. This movement of electrons inside the conductor and received the name of electricity. But any movement in nature - let that movement of water in the river, movement of air masses or charges, can make certain useful work. And this is interesting from a practical point of view. Knowing the power, the duration of the impact, the direction of application of any force, you can use it to solve certain vital issues.

Therefore, scientists are so busy studying the environment and creating devices that allow everything to be measured and calculated. To obtain ideas about the current, the device was invented an ammeter. It allows you to determine the number of charged particles that per unit time pass through a known section of the conductor, that is, the current.

What is an ammeter, its types

An ammeter can measure the current in any electrical circuit. This device is easy to recognize, it is denoted by the Latin letter A. Since the current is of different magnitude, starting from milliamperes and above, there are different in power devices or universal, in which the measurement limit changes. And for a constant and an alternating current , different types of ammeters are needed.

According to the principle of device, devices can be:

• Electromagnetic design.
• Magnetoelectric.
• Thermal.
• Detector type.
• Induction.
• Electrodynamic system.
• Photovoltaic.
• Thermoelectric.

A magnetoelectric device can determine the current in circuits connected to a constant voltage. Detector and induction type - measure alternating currents. All other species can be universal.

High sensitivity and accuracy of indications are the ammeters of electrodynamic and magnetoelectric performance.

How to connect an ammeter to an electrical circuit

An ammeter of any type is connected in series to a load in an electrical circuit. Then through it passes the same current as through the circuit. In order not to influence the current, not to interfere with it, the device is made with a small input resistance. We must remember that by connecting the ammeter in parallel with the load (wrong connection), all the current will go through it according to the principle of least resistance. Forgetting how to connect an ammeter, you can simply burn the device!

Before selecting a device, you need to know the type of current - alternating or permanent. After this, taking the appropriate ammeter (in the marking of the scale, usually indicate the sign of the wave for the alternating voltage and the straight line for the constant) set the maximum measurement limit on it and only then think about how to connect the ammeter to the circuit. After this, it is necessary to read the instrument. If they are much smaller than the set measurement limit, for example, the arrow is in the first half of the scale counting from zero, then it is necessary to rearrange the limit one by one. More accurate are the readings when the arrow is located in the second half of the scale.

Measurement of DC values

Constant currents are present in many electronic circuits, especially for power supplies, various chargers. To repair such devices, masters need to know how to connect an ammeter. In practice, an ordinary person, not connected with radio electronics, can also apply this knowledge, for example, to determine how much the battery is holding the battery from the camera.

Take a fully charged battery. Suppose its nominal voltage is 3.5 volts (V). Pick up a light bulb at such a denomination and collect the diagram: the battery - the measuring device - the bulb. Write down what the ammeter shows. For example, a lamp consumes a current of 150 mA (mA), and the battery writes a capacity of 1500 mA (mAh), which means that a good battery should give a current of 150 mA for about 10 hours!

Measurement of alternating current values

Any household electric appliance is a load that consumes an alternating current. But, considering the issues of household electricity use, the important thing is the power, because they pay exactly for kilowatts (kW). What is an ammeter in this case? Instrument of indirect measurement. With the help of it, recognize the current and apply the formula:

P = IU (Ohm's law), where I is the current strength (A), U is the voltage (V),

Calculate the power (P) (W).

For example, the device lost information about its parameters, in this case it is impossible to do without measurements. Or you need to calculate the power consumption of electricity in a building where it is simply impossible to take into account all the devices. Then, at the entrance to the power panel, connect a powerful ammeter and make measurements. But in the latter case, you need a tolerance, which only professional electricians have!

Non-contact current measurement method

Sometimes it is technically impossible to break the electric circuit to switch on the measuring device, but it is necessary to measure the current (with regard to ordinary and high-voltage electric circuits). How to connect an ammeter in this case? For this purpose, a device for non-contact current measurement was developed-current clamps. The principle of its operation is based on the fact that any current passing through the conductor creates some electromagnetic field. The magnitude of this field is the greater, the greater the current strength. By measuring the field strength factor and transforming these data, a real value of the force, expressed in amperes, is obtained.

This is a very convenient way of measuring, because you do not have to think long how to connect an ammeter. To the charger and any electrical circuit, you can connect the pliers directly to an insulated wire and take readings.

Why you need to monitor the charging current in the battery

It seems that it's easier: connected the car battery to the charger, waited ten hours and it's done - it's charged. In fact, it is very important to monitor the charge current, recharging is also harmful, as well as not fully charged battery. This may shorten the life of the device. Therefore, it is advisable to consider how to connect an ammeter to the charger.

When the circuit is assembled and turned on, the ammeter displays the value of the charge current. If the battery is healthy, but discharged, it will gradually take charge. That is, the charge current will slowly decrease (for several hours) until it stops at a certain value. When this happens, it is advisable to disconnect the battery from the charger. If there is a sharp decrease in current from the initial value (within half an hour), then the battery may be faulty.

In very good chargers there is a function of adjusting the charging current. Then, at the beginning of the process, you should set the charging current ten times smaller than the nominal capacity of the battery, which is indicated in its technical parameters.