How to calculate the current consumed by a household appliance?

Introduction to the topic of determining quantities

The generally accepted unit for measuring power is the watt (W).
This parameter usually describes the rate of energy conversion or consumption. By definition, power is the ratio of work (energy expended) to the time it is performed. In turn, the unit of energy in the International System of Units (SI) has always been the Joule. The value of “1 watt” in question corresponds to one Joule of work done in 1 second (J/s). For example, in electrical engineering there are special devices, wattmeters, that measure the power of an electric current or electromagnetic signal.

The unit received its name from the surname of the Scots-Irish inventor James Watt (Watt). This creator of the first steam engine first used it in describing the capabilities of a power machine. The watt was adopted in 1882 and largely replaced the traditional units of account that had existed before: foot-pound-force per minute and draft horsepower. The first unit of power corresponded to 2260 watts. As for the second, it is still used today: “metric horsepower” is approximately 735 watts.

As a unit named after a scientist, it follows the spelling rules originally adopted by the SI system. The name watt is written with a lowercase letter, and the designation W (W), including in the designation of non-system units, is written with a capital letter.

The use of the watt is not limited to the field of electrical engineering; it measures the torque of power plants, the flow of thermal and acoustic energy, and the intensity of ionizing radiation.

One watt – is it a lot or a little? Mobile phone transmitters usually have a power of 1 W. Incandescent lamps used in household lamps consume power of 25, 40, 60, 100 W, TV and refrigerator 50–55, microwave and vacuum cleaner 1000, and washing machine 2500 W.

Often in practice it is necessary to convert watts into kilowatts or, conversely, convert kilowatt values ​​into watts.

Power calculation formulas

Power is a physical quantity equal to the ratio of the amount of work to the time of doing this work. Electric current power (P) is a quantity that characterizes the rate of conversion of electrical energy into other types of energy. The international unit of measurement is Watt (W/W).

— Power by current and voltage (direct current): P = I × U — Power by current and voltage (single-phase alternating current): P = I × U × cos φ — Power by current and voltage (three-phase alternating current): P = I × U × cos φ × √3 - Power by current and resistance: P = I2 × R - Power by voltage and resistance: P = U2 / R

• I – current strength, A;
• U – voltage, V;
• R – resistance, Ohm;
• cos φ – power factor.

This is interesting: How to reset errors on a Volkswagen Polo sedan

How many watts are in an ampere, how to convert amperes to watts and kilowatts

Not every housewife will immediately figure out how to convert amps into watts or kilowatts, or vice versa - watts and kilowatts into amperes.

Why might this be needed? For example, the following numbers are indicated on the socket or plug: “220V 6A” - a marking that reflects the maximum permissible power of the connected load.

What does it mean? What is the maximum power of a network device that can be plugged into such an outlet or used with this plug?

To get the power value, just multiply these two numbers: 220 * 6 = 1320 watts - the maximum power for a given plug or socket. For example, an iron with steam can only be used at two, and an oil heater can only be used at half power.

What is current strength:

Converting watts to amperes

Or the case when power in watts needs to be converted into amperes. This is the problem faced, for example, by a person who decides to choose a circuit breaker for a water heater.

On the water heater it is written, for example, “2500 W” - this is the rated power at a network of 220 volts. Therefore, to get the maximum amps of the water heater, we divide the rated power by the rated voltage, and we get: 2500/220 = 11.36 amps.

So, you can choose a 16 amp machine. A 10-amp circuit breaker will clearly not be enough, and a 16-amp circuit breaker will work as soon as the current exceeds the safe value. Thus, to get amperes, you need to divide the watts by the supply volts - divide the power by the voltage I = P/U (volts in a household network 220-230).

How many amperes are in a kilowatt and how many kilowatts are in an ampere

Since there are 1000 watts in one kilowatt, then for a mains voltage of 220 volts we can assume that there are 4.54 amperes in one kilowatt, because I = P/U = 1000/220 = 4.54 amperes.

The opposite statement is also true for the network: in one ampere there are 0.22 kW, because P = I*U = 1*220 = 220 W = 0.22 kW.

For approximate calculations, it can be taken into account that with a single-phase load, the rated current I ≈ 4.5P, where P is the power consumption in kilowatts. For example, with P = 5 kW, I = 4.5 x 5 = 22.5 A.

What to do if the network is three-phase

To find the total power, multiply the line voltage, current, and multiply by √3. We have: P = 380*0.83*1.732 = 546 watts. To find amperes, it is enough to divide the power of the device in a three-phase network by the value of the line voltage and by the root of 3, that is, use the formula: I = P/(√3*U).

• Conclusion
• Knowing that the power in a single-phase network is equal to P = I*U, and the voltage in the network is 220 volts, it will not be difficult for anyone to calculate the appropriate power for a particular current value.
• Knowing the inverse formula that the current is equal to I = P/U, and the voltage in the network is 220 volts, everyone can easily find amperes for their device, knowing its rated power when operating from the network.

Calculations are carried out similarly for a three-phase network, only a coefficient of 1.732 is added (the root of three is √3). Well, a convenient rule for network single-phase devices: “there are 4.54 amperes in one kilowatt, and 220 watts or 0.22 kW in one ampere” - this is a direct consequence of the above formulas for a network voltage of 220 volts.

Three-phase network voltage 380 V

With a three-phase power supply, the current strength I (in amperes, A) is calculated by the formula:

I = P /1.73 U,

where P is power consumption, W;

U—mains voltage, V,

since the voltage in a three-phase power supply circuit is 380 V, the formula will take the form:

I = P /657.4.

If a three-phase power supply with a voltage of 380 V is supplied to the house, the connection diagram will look as follows.

Calculation

Special formulas are used to calculate values. After counting them, all that remains is to insert them into the above formulas. To find the electric current, you need to divide the voltage by the conductor resistance, and to find the power, you need to multiply the voltage by the current force or double the current value by the resistance. It is also possible to divide the double voltage value by the resistance.

Note! Often all the necessary data is written on the box or technical specifications on the manufacturer’s website. Often the information is indicated in kW and can easily be converted into amperage using a converter. Another simple option for determining energy consumption and amperage is to study the consumer's electric meter or circuit breaker

But in this case, you only need to connect one device to the network

Another easy way to determine energy consumption and amperage is to examine the consumer's electric meter or circuit breaker. But in this case, it is necessary to connect only one device to the network.

Calculation formula

What are amps

You should brush up on the definition of current, which is expressed in amperes. From a physics course we know that the strength of the current is determined by the amount of charge transferred through the volume over a certain period of time. This is not clear and not always clear.

It is easier to accept that current is the amount of heating of the elements of an electrical circuit. The greater the current, the greater the amount of heat will be released.

A large number of household and industrial appliances and devices use the heating property of current:

• Heating devices (electric stoves, kettles, irons).
• Incandescent lamps (glow from an overheated filament).

The simplest electric boiler.
Fuses used for short circuit protection also use the heating property of current. In fuses, this is the burnout of a thin calibrated wire; in circuit breakers, this is the bending of a bimetallic plate.

Fuse device

Examples in nature and technology[ | ]

Electricity

For simplicity, electrical parameters are often explained using the example of water moving through pipes. This term, expressed in amperes (A), denotes the speed of movement of electrons in a conductor. Obstacles to liquid are created by the small size and distance of the transport system. Resistance to electric current is influenced by:

• presence of free electrons, chemical purity of the material;
• cross-sectional area (length) of the wire;
• temperature conditions.

Electricity

Calculators for converting watts to amperes and vice versa

Despite the rather simple formulas and even the available conversion factors, it is still easier for many users to carry out such transformation of quantities using calculators. Well, let's give them that opportunity.

Below are two calculators - for converting current into load and vice versa. In order not to split into various nuances, both calculators are made universal, that is, they can be used for direct current networks, single-phase and three-phase alternating current, for devices with and without reactive loads.

If you do not specify the power factor (Cos φ) in the last input field, then it is assumed to be equal to one, that is, there is no reactive power by default.

The user selects and indicates everything independently in the appropriate fields of the application - and then by pressing the “CALCULATE …” button, displays the finished result. Fast and accurate!

Interaction of current and magnetic field

The magnetic induction vector is considered positively directed if it coincides with the magnetic needle oriented to the north pole. Using this rule, you can determine the direction of the MI vector at any point in space and visually represent the structure of the magnetic field. The figure below shows an example of the location of MI lines for a permanent magnet and a coil with current.

Ampere was able to calculate how the interaction would take place between a magnetic field with a given strength and a conductor through which current flows. According to his law, the effect of a magnetic field on a current-carrying conductor is described using the following formula:

This formula is presented in vector form. Multiplication between vectors is performed according to special rules. As a result of this operation, a vector will be obtained, the absolute value of which is determined by the following differential formula:

For a straight wire, this formula in scalar form has the form:

Although the law appears to be quite simple, it was an important achievement in the development of physical science.

380 volt networks

Converting current values ​​into power for a three-phase network does not differ from the above, it is only necessary to take into account the fact that the current consumed by the load is distributed over three phases of the network. The conversion of amperes to kilowatts is carried out taking into account the power factor.

In a three-phase network, you need to understand the difference between phase and line voltages, as well as line and phase currents. There are also 2 options for connecting consumers:

1. Star. 4 wires are used - 3 phase and 1 neutral (zero). The use of two wires, phase and neutral, is an example of a single-phase 220 volt network.
2. Triangle. 3 wires are used.

The formulas for converting amperes to kilowatts for both types of connection are the same. The only difference is in the case of a delta connection for the calculation of separately connected loads.

Star connection

If you take a phase conductor and a neutral conductor, then there will be a phase voltage between them. The voltage between phase wires is called linear, and it is greater than the phase one:

Ul = 1.73•Uph

The current flowing in each of the loads is the same as in the network conductors, therefore the phase and line currents are equal. Provided the load is uniform, there is no current in the neutral conductor.

The conversion of amperes to kilowatts for a star connection is made using the formula:

P=1.73•Uл•Iл•cosø

Delta connection

With this type of connection, the voltage between the phase wires is equal to the voltage on each of the three loads, and the currents in the wires (phase currents) are related to the linear ones (flowing in each load) by the expression:

Il = 1.73•Iph

The translation formula corresponds to the one given above for the “star”:

P=1.73•Uл•Iл•cosø

This conversion of values ​​is used when choosing circuit breakers installed in the phase conductors of the supply network. This is true when using three-phase consumers - electric motors, transformers.

If separate loads connected by a triangle are used, then the protection is placed in the load circuit; the formula for calculation uses the value of the phase current:

P=3•Uл•Iф•cosø

The reverse conversion of watts to amperes is carried out using reverse formulas, taking into account the connection conditions (connection type).

A pre-compiled conversion table will help you avoid calculations, which shows the values ​​for the active load and the most common value cosø=0.8.

Table 1. Conversion of kilowatt values ​​into amperes for 220 and 380 volts with cosø correction.

Read further:

How to convert amps to watts and vice versa?

What is active and reactive power of alternating electric current?

What is a voltage divider and how to calculate it?

What is phase and line voltage?

How to convert kilowatts to horsepower?

Ampere – Watt conversion table

To convert watts to amperes, you need to use the previous formula, expanding it. To calculate the current, you need to divide the power by the voltage: I = P/U. The following table shows the amperage for devices with different voltages - 6, 12, 24, 220 and 380 volts.

Remember that for high voltage networks, the specified amperage differs depending on the efficiency.

Table of the ratio of amperes and watts, depending on voltage.

Using the table it is also easy to determine the power if the voltage and current are known. This is useful not only for calculating energy consumption, but also for choosing special equipment responsible for uninterrupted operation or preventing overheating.

Necessary calculations

First you need to check the sockets that are connected to the selected machine. Sometimes an automatic device powers not only household appliances, but also lighting devices. If the electrical wiring in the house is not installed correctly, the entire supply may depend on only one device. They count the total number of consumers and add up the voltage they need to operate.

The result will be the sum of watts that the automatic device supplies to these devices. Most likely, the equipment will not be connected at the same time, but the formula will make it possible to calculate the maximum voltage consumption. If some device does not indicate a specific power, but its interval, then it is necessary to take the largest value.

Minimum values ​​are not taken into account, since in this case the machine will operate at full load. This is unacceptable, because there are interruptions in the network, and this will lead to breakdown of the disconnecting device. The voltage in private homes and in industrial enterprises is different. There are two types:

• single-phase network - 220 V;
• two-phase - 380 volts.

How to calculate voltage and current power

Above we showed formulas that can be used to calculate any value based on known values.

There is a well-known formula for determining power based on current and voltage. Before finding ampere the formula must be converted as follows:

If the device indicates what power consumption and current strength in the circuit, then you can determine what voltage the device is designed to work with:

Also, using additionally Ohm's law, you can determine the value of the load resistance. To avoid confusion in formulas, you can use a mnemonic notation that allows you to easily calculate any of the values ​​when any two others are known.

Mnemonic notation of electrical quantities

Tables of ratios of amperes, volts, watts, ohms

To simplify, the main parameters of the electrical circuit are explained using the example of the functioning of a conventional pipeline. The movement of fluid is ensured by the pressure difference. The narrowing (expansion) of the transport route changes the flow resistance accordingly. If necessary, using the listed parameters or experimentally, you can set the pipeline productivity in liters per unit of time.

By analogy with the above description, the potential difference (voltage) ensures the movement of electric charges (current). As the cross-section of the conductor decreases, the electrical resistance increases. Knowing the basic parameters, it is easy to calculate the power consumption of the connected load.

Table for calculating the comfort zone of “electronic” cigarettes

The specified power data corresponds to certain resistance and voltage values. Similar tables are compiled for converting Watts into amperes and other quantities. This example clearly demonstrates the main disadvantages of the tabular form:

• complexity of processing large amounts of data;
• discreteness of information provision;
• limited accuracy.

Graphical representation of basic formulas for calculating electrical parameters

Using calculations, you can convert volts to amperes quickly and accurately.

For your information. As an alternative, an electrical quantity converter is used, which is available for free use on reference and specialized websites on the Internet.

How to calculate the number of amperes in the network

In practice, different calculation schemes are used. In particular, they use automated programs (calculators). Such tools are offered free of charge by specialized websites online. Below are formulas and examples that will help you calculate electrical parameters yourself.

How to find out the current, knowing the power and voltage

The DC power source (battery) provides an output voltage of 12 Volts. The known power consumption is 2 W. How to calculate amperage is shown in the example:

For your information. For convenience, fractional and multiple values ​​are used in practice. In this example, 167 mA (milliamps).

How to find out voltage by knowing current strength

The above shows how to calculate amperes, knowing the power and voltage. The same formula is used for the reverse action. If the current is 200 mA, with a power of 2 W at the measurement points, the device will display the following voltage:

U = P/I = 2/0.2 = 10 V.

How to calculate power knowing current and voltage

The result can be calculated using the following example:

P = I*U = 0.2 * 10 = 2 W.

On the left side of the figure is the formula for calculating mechanical power:

• A – useful work in Joules;
• t – time period for which this operation was performed.

How to determine the power of a circuit with a resistance tester

In real conditions, the electrical resistance of the conductor has a significant influence. By selecting the appropriate mode, you can find out the actual value using a multitester. The switch is set to a position that corresponds to a certain range. They move from large values ​​to small ones until an indication appears on the screen.

When R = 20 Ohm, knowing the current strength I = 200 mA, the power is calculated using the following formula:

P = I2*R = 0.04*20 = 0.8 W.

If necessary, specify the voltage:

Online calculator for converting Watts to Amps to determine the load

Electrical systems often require complex analysis when designing, because you need to deal with many different quantities, watts, volts, amperes, etc.

In this case, it is precisely necessary to calculate their ratio at a certain load on the mechanism.

In some systems, the voltage is fixed, for example, in a home network, but power and current mean different concepts, although they are interchangeable quantities.

Online calculator for calculating watts to amperes

To obtain the result, be sure to indicate the voltage and power consumption.

In such cases, it is very important to have an assistant in order to accurately convert the wattage into amperes at a constant voltage value. An online calculator will help us convert amperes to watts. Before using an online program to calculate values, you need to have an idea of ​​the meaning of the required data

Before using an online program to calculate values, you need to have an idea of ​​the meaning of the required data

An online calculator will help us convert amperes to watts. Before using an online program to calculate values, you need to have an idea of ​​the meaning of the required data.

1. Power is the rate at which energy is consumed. For example, a 100 W light bulb uses energy - 100 joules per second.
2. Ampere is a measurement of electric current, determined in coulombs and shows the number of electrons that passed through a certain cross-section of a conductor in a specified time.
3. The voltage of an electric current is measured in volts.

Attention: if the quantity indicator has a fractional number, then it must be entered into the system using a period, not a comma. Thus, the power calculator allows you to convert watts into amperes in a matter of time, you don’t need to write out complex formulas and think about their calculation.

sewing

Everything is simple and accessible!

sewing. Everything is simple and accessible!

General understanding of the electromagnetic field

For a long time, ideas about the electric and magnetic fields were not connected with each other. Practical experiments confirmed that each of them has its own special properties. Research by Faraday and Maxwell showed that there is an electromagnetic field that can manifest itself as either electric or magnetic. It can be described with the power of a tension vector. If you know the magnitude and direction of a given vector, you can calculate the force of impact.

The first scientist to pay attention to the mutual influence of the magnetic field and current was the famous scientist H. K. Ørsted. He studied the effect of a conductor with current flowing through it on the position of the compass needle. After this, scientists began to systematically study various interaction options.

Ampere was born in 1775 in Lyon. Since childhood, he showed a passion for mathematics. As a teenager, he studied the works of Euler and Lagrange. Ampere became a professor of mathematics in 1809, and in 1814 he was elected to the Academy of Sciences. Although he primarily studied mathematics, he was interested in physics and some other sciences.

Ampere was not the first person to show interest in the connection between magnetic and electric fields, but he was the first to try to find an accurate mathematical description of the processes occurring. He not only established the fact of interaction between electric currents, but also formulated the law of this phenomenon.

Ampere proved that conductors begin to interact if a current flows through each of them. In this case, repulsive or attractive forces arise between them. In 1826, Ampere first published the results of his research, with the help of which he studied the interaction of parallel currents.

The figure below shows a diagram of one of Ampere's experiments, which measures the force acting on a current-carrying conductor in a magnetic field. The red arrow in the figure shows the direction of the current.

Based on experiments, the scientist made an assumption, which was later called the “Ampere hypothesis.” Understanding how current affects the magnetic field, he was able to prove that matter consists of a collection of extremely small circular currents. Each of them generates a very weak magnetic field. Since all these currents are randomly oriented, the magnetic field practically does not appear externally. However, in magnets all circular currents are equally directed and their effects add up. This explains their special properties and practical use.

Ampere, using his law, also explained the effect of magnetization. According to him, in some substances, under the influence of a magnetic field, circular currents are ordered, and they are gradually oriented in one direction.

This hypothesis became one of the sources of the theory of magnetism. She was able to explain the phenomenon only partially, since she did not answer the question of why some substances are only slightly affected by an external magnetic field. The question also remains unexplained: why, during magnetization, some substances create a magnetic flux co-directed with the external field (paramagnets), while others create a magnetic flux in the opposite direction (diamagnets).

Converting time units

From previous lessons we know that the basic units of time are:

• seconds
• minutes
• watch
• day

Any quantity that characterizes time can be converted from one unit of measurement to another. For example, 15 minutes can be converted into seconds, hours, or days.

In addition, when solving problems in physics, it is imperative to comply with the requirements of the international SI system. That is, if time is given not in seconds, but in another unit of measurement, then it must be converted into seconds, since the second is a unit of time in the SI system.

To convert time from one unit of measurement to another, you need to know what a particular unit of time consists of. That is, you need to know that, for example, one hour consists of sixty minutes or one minute consists of sixty seconds, etc.

Let us show with a simple example how to reason when converting time from one unit of measurement to another. Let's say you want to convert 2 minutes to seconds.

Since we are converting minutes to seconds, we first need to find out how many seconds are contained in one minute. There are sixty seconds in one minute:

1 min = 60 s

If in seconds, then how many seconds are there in two such minutes? The answer suggests itself - 120 seconds. And these 120 seconds are obtained by multiplying 2 by 60. This means that to convert 2 minutes into seconds, you need to multiply 2 by 60

2 × 60= 120 s

Now let's try to convert the same 2 minutes into hours. Since we are converting minutes to hours, we first need to find out how many minutes are contained in one hour. One hour contains sixty minutes:

1 hour = 60 m

If one hour contains 60 minutes, then an hour that contains only 2 minutes will be much less. To get it you need to divide 2 minutes by 60

When dividing 2 by 60, the resulting periodic fraction is 0.0 (3). This fraction can be rounded to the hundredths place. Then we get the answer 0.03

2: 60= 0.03h

When converting time units, a diagram is also applicable that makes it easier to figure out whether to use multiplication or division:

For example, let's convert 25 minutes to hours using this scheme.

So we have to go from minutes to hours. In other words, move from a lower unit of measurement to a higher one (hours are older than minutes). We look at the diagram and see that the arrow indicating the transition from lower to higher units is directed upward and at the end of the arrow it is indicated that we must apply division:

Now you need to find out how many minutes are in one hour. One hour contains 60 minutes. And an hour that contains only 25 minutes will be much less. To find it, you need to divide 25 by 60

When dividing 25 by 60, the resulting periodic fraction is 0.41 (6). This fraction can be rounded to the hundredths place. Then we get the answer 0.42

25:60 = 0.42 h

Calculation of cosine phi (cos φ)

φ is the shift angle between the phase of current and voltage, and if the latter leads the current, the shift is considered positive, if it lags, it is negative.

cos φ is a dimensionless quantity that is equal to the ratio of active power to total power and shows how efficiently energy is used.

Formula for calculating cosine phi: cos φ = S / P

• S – total power, VA (Volt-ampere);
• P – active power, W.

Active power (P) is the real, useful, real power, this load absorbs all the energy and turns it into useful work, such as light from a light bulb. There is no phase shift.

Formula for calculating active power: P (W) = I × U × cos φ

Reactive power (Q) is watt-free (useless) power, which is characterized by the fact that it does not participate in work, but is transmitted back to the source. The presence of a reactive component is considered a detrimental characteristic of a circuit, since the main purpose of the existing power supply is to reduce costs, and not to pump it back and forth. This effect is created by coils and capacitors.

Formula for calculating reactive power: P (VAR) = I × U × sin φ

The total power of an electrical appliance (S) is a total value that includes both active and reactive components of power.

Formula for calculating apparent power: S (VA) = I × U or S = √( P2 + Q2)

What is tension? Volt [V]

Voltage is a physical quantity that characterizes the ratio of the work of the electric field in the process of transferring a charge from one point A to another point B to the value of this same charge. Simply put, it is the potential difference between two points. Measured in Volts.

The voltage is essentially similar to the amount of water pressure in the pipe; the higher it is, the faster the water flows from the tap. The voltage is standardized and the same for all apartments, houses and garages, equal to 220 Volts with single-phase power supply. Also allowed according to GOST is a 10 percent deviation for the home electrical network. The voltage must be no less than 198 and no more than 242 Volts.

Read more: Vacuum pumping of oil from the engine

1 Volt contains:

• 1,000,000 microvolts
• 1,000 millivolts

What is Current Strength. Ampere [A]

Current is the speed at which electrical charge flows through a conductor. One ampere is equal to a charge of one coulomb that passes through a conductor in one second. One coulomb represents a very large charge, so in most devices this value is measured in milliamps.

The current strength depends on the cross-section of the conductor and its length. This must be taken into account when planning structures, as well as choosing electrical appliances. Although most should not think about this, since this is the task of engineers and designers.

How many watts are in 1 ampere?

To determine the power of a circuit, the concept of voltage is also important. This is the electromotive force that moves electrons. It is measured in volts. Most devices have this characteristic in their documentation.

How to correctly calculate amperes by power and voltage

In order to make calculations correctly, all quantities used must be of the same dimension, that is, if power is expressed in watts, then voltage must be expressed in volts, and current in amperes.

If you operate with a power of kilowatts, then, accordingly, the voltage should be in kilovolts and the current in kiloamperes.

Note! The last case is typical only for powerful energy, and in everyday life they usually use watt, volt and ampere. It is better to update the rules for converting multiple units in memory:. It is better to update the rules for converting multiple units in memory:

It is better to update the rules for converting multiple units in memory:

• Kilo - thousand;
• Kilowatt - thousand watts (1 kW = 1000 W);
• Kilovolt - thousand volts (1 kV = 1000 V);
• Kiloampere - one thousand amperes (1kA = 1000A);
• Milli - one thousandth;
• milliwatt - one thousandth of a watt (1 mW = 0.001 W);
• millivolt - one thousandth of a volt (1mV = 0.001V);
• milliamp - one thousandth of an ampere (1mA = 0.001A).

Nowadays, a large number of household appliances consume power of more than a kilowatt, so for correct calculations you need to convert this value into watts.

For example: On the electric kettle it is written that the power consumption is 1.8 kW. In order to calculate the current value when connecting to a 220 V household network, 1800 W must be substituted into the formula. Then the output is a current in amperes.

Closed Loop Effect

Using Ampere's law, we can draw a conclusion about what the magnetic field of a closed loop will be. For example, you can vertically orient a frame in a field whose field lines are directed from top to bottom.

To determine which direction the magnetic induction will have in this situation, you should also use the left-hand rule. Since the current in the lower part of the frame is directed to the right, the hand must be positioned so that the fingers are directed, if you look at the drawing, also to the right. In this case, the palm should be open upward. The thumb in such a situation will be directed away from the observer.

Applying this rule to the top of the frame, one can see that the Ampere force acts towards the observer. That is, the frame is given a rotational movement. However, as you approach the horizontal position, this force decreases.

If the frame has inertia and thanks to it it slips past the horizontal position, then the forces described above will begin to act again: weakly at first, and then will increase as the frame reaches a vertical position.

How to convert watt to ampere

You need to convert watts to amperes in a situation where you need to install a protective device and you need to choose what rated current it should have. It is clear from the operating instructions how many watts a household appliance connected to a single-phase network consumes.

The task is to calculate how many amperes in watts or what kind of socket to connect to if the microwave oven consumes 1.5 kW. For ease of calculation, it is better to convert kilowatts into watts: 1.5 kW = 1500 W. We substitute the values ​​into the formula and get: 1500 W / 220 V = 6.81 A. We round the values ​​up and get 1500 W in terms of amperes - microwave current consumption is at least 7 A.

Watch this video on YouTube

If you connect several devices simultaneously to one protection device, then in order to calculate how many amperes there are in watts, you need to add all the consumption values ​​together. For example, the room uses lighting with 10 pcs LED lamps. 6 W, iron 2 kW and TV 30 W. First, all indicators need to be converted into watts, it turns out:

• lamps 6*10= 60 W,
• iron 2 kW=2000 W,
• TV 30 W.

60+2000+30=2090 W.

Now you can convert amperes to watts, to do this we substitute the values ​​in the formula 2090/220 V = 9.5 A ~ 10 A. Answer: current consumption is about 10 A.

You need to know how to convert amps to watts without a calculator. The table shows the correspondence between the rate of electricity consumption and the current strength for single-phase and three-phase networks.

How to convert amperes to kilowatts?

How many watts are in a kilowatt?

How to convert kilowatts to horsepower?

Methods for calculating electricity consumption of household appliances

What is active and reactive power of alternating electric current?

How to choose a circuit breaker based on power and load current?

Calculation through resistance

Electricity flowing through wires can be compared to water flowing through a river bed. The wider the channel, the less resistance and the greater the amount flows along the channel per unit time. The flow of current in a conductor is limited by the current resistance, which, in turn, is measured in Ohms.

Source: pixabay

To calculate the current through a resistance, we can use Ohm's law. The resistance of devices is often also indicated on the device nameplate. The resistance of the wires connecting the socket and the device can be ignored and considered infinitesimal.

Ohm's Law states that voltage equals current times resistance, so if you divide the voltage of your power supply by the load resistance, you will find the current in amps. For example, if we connect a washing machine with a resistance of 40 Ohms to a 220 V outlet, we find out that the machine consumes a current of 5.5 A.

Still have questions? Write in the comments, let's figure it out together!

Administrator.

I am interested in programming and radio electronics. I study at a radio engineering college in the correspondence department.

Source

What is voltage - Volt [V]

Voltage indicates the potential ability of electricity to do useful work (measured in Volts or V). The higher it is, the less current is required for the same power, which has a beneficial effect on the thickness and mass of copper in the supply wires. After all, they are heated by passing current, and this is an unproductive loss, so the main electricity transmission lines operate under very high voltage.

In cars, for safety reasons, as well as by tradition, a voltage of 12 volts is used. In heavy trucks, where consumption is high, the voltage is raised to 24 volts, and electric vehicles, with their powerful traction motors, are powered by their batteries with a voltage of 400 volts and above. It's dangerous, but there's no other way out.

Why do you need to calculate current?

Most electrical appliances indicate power consumption. This is necessary in order to correctly record electricity consumption. But for everything else, the power value carries little information. The parameters of circuit breakers and fuse links, the cross-section of the electrical wiring, require knowledge of the flowing current or, as electricians say, the load amperage.

A simple example: which soldering iron overloads electrical wiring more, a 42-volt 80-watt one or a 220-volt 100-watt one? The logical answer, which is more powerful, is incorrect. Indeed, in fact, when the second soldering iron is turned on, a current of about 0.5 A flows in the network, and when the first one is turned on, almost 2 A. Accordingly, such devices require different electrical wiring and ratings of protective devices. With the same thickness of power wires, the heating will be stronger when working with a low-voltage tool.

For the same reason, power lines strive to maximize the transmitted voltage. Since the load power remains the same, at higher voltages less current flows through the wires and therefore:

• Losses are reduced;
• Heating is reduced;
• The cross-section of the wires is reduced and, as a result, their weight and the load on power line supports are reduced.

High voltage power line support

Why do you need current calculation?

Let's count lighting together!

To calculate amperes by power for AC networks with reactive loads, appropriate corrections are needed. Such consumers shift the current vector by 90° forward (backward) with respect to the voltage with capacitive (inductive) characteristics, respectively.

Current calculation for a single-phase network

The change in current, voltage and power according to a sinusoidal graph explains the meaninglessness of measuring instantaneous values. The parameters are calculated taking into account time intervals. As a rule, the full period of one oscillatory cycle is used.

Current, voltage and power in a single-phase network with the connection of active, inductive, capacitive reactance

A generator with a significant value of the reactive component will perform its functions less efficiently. In this case, part of the power will not perform useful work.

Current calculation for a three-phase network

This option can be represented as a combination of several single-phase networks. When represented by vectors on the complex plane, a phase shift of 120° will be visible.

Three-phase network

The figures show a voltage of 220 V in each phase and a linear value of 380 V. You should pay attention to the current in the neutral conductor (I0), which does not perform useful functions. It is created due to the uneven distribution of connected loads.

How to calculate current power

To correct inductive (capacitive) components, an extended calculation formula is used:

P = I*cos ϕ.

In the absence of such loads, an additional factor is taken equal to one.

This ampere table will help you select the appropriate circuit breaker (fuse) taking into account the parameters of the connected equipment.

Dependence of current on power consumption

How to convert watts to amperes

To connect the electric motor, you need to take the cos ϕ value from the accompanying documentation. This data is duplicated in a special tag attached to the case. How to calculate amperes for a three-phase network is shown by the following formula:

I = P/(√3*U*cos ϕ).