Features of the volt-amp power unit

How is current measured?

Units of measurement of the main indicators of the electrical network: ampere, watt (kilowatt), volt. In this case, the current strength is measured in amperes and shows the speed of charge passing through the conductor over a certain period of time.

Instruments for measuring current strength

The current strength of the electrical network is measured by a special device - an ammeter. The type of equipment depends on the network voltage (DC or AC). The data obtained is used to determine the maximum load on the wiring, as well as to calculate the rated and actual power of the electrical appliances used.

What is current (Ampere)

It is important for the user to calculate the rated current of the electrical network in advance. The choice of cross-section of the wiring cores, as well as the equipment of the safety circuit breaker, depends on this.

What is voltage (Volts)

The concept of “voltage” includes the energy required to move an electric charge over a certain distance in a specified period of time. This indicator is measured in volts.

What is power (Watt)

The power indicator determines the rate of energy consumption over a certain period of time. Power is measured in watts or kilowatts, but there is also the concept of kilowatt/hour, according to which all consumers are charged for the electricity actually used.

Typically, manufacturers indicate the power consumption of electrical appliances (watts, kilowatts), it can be seen on the packaging or product passport

When connecting powerful equipment, it is also important to calculate a sufficient reserve of sockets or machines, the parameters of which are measured in amperes. To connect safely, it is important to understand the difference between these concepts and be able to quickly convert amps to watts and vice versa

Using the online calculator on our website, you can do this in a matter of seconds.

Power of household electrical appliances

Household electrical appliances usually have a wattage rating. Some fixtures limit the wattage of the bulbs they can use, such as no more than 60 watts. This is done because higher wattage lamps generate a lot of heat and the lamp socket may be damaged. And the lamp itself will not last long at high temperatures in the lamp. This is mainly a problem with incandescent lamps. LED, fluorescent and other lamps typically operate at lower wattages for the same brightness and, if used in fixtures designed for incandescent bulbs, wattage is not an issue.

The greater the power of an electrical appliance, the higher the energy consumption and the cost of using the device. Therefore, manufacturers are constantly improving electrical appliances and lamps. The luminous flux of lamps, measured in lumens, depends on the power, but also on the type of lamp. The greater the luminous flux of a lamp, the brighter its light appears. For people, it is the high brightness that is important, and not the power consumed by the llama, so lately alternatives to incandescent lamps have become increasingly popular. Below are examples of types of lamps, their power and the luminous flux they create.

Object of measurement

To determine volt-amperes (V•A), you will need to perform the following measurements:

1. First you will need to measure the current in amperes (A). This is the SI unit of I.
2. Next, the voltage should be measured in SI units - volts. It will show the force required for the flow of electric current in volts (V).
3. Calculate P - the amount of energy produced by current and volts together. Multiplying amperes (A) by volts (V) gives the resultant or energy.

Measuring quantities

Direct current (—), or DC, is inherent in the process when it flows in one direction, for example, a flashlight with a battery uses a constant indicator. Alternating current (~) or AC refers to processes with alternating direction of electron movement, due to which it periodically changes its direction. In North America and Western Japan this occurs 60 times per second at a frequency of 60 Hz. In Russia, the EU, most of Australia, South America, Africa and Asia, the frequency is 50 Hz.

Watt's law formula

To convert these quantities, the formula of Watt's law is used:

Power (P) = Current (I) x Voltage (V), the same in units: watt = ampere x volt. To find amplifiers, use the Watt formula in reverse and divide the power by the voltage: Current (I) = Power (P) ÷ Voltage (V) I = 600 W : 120 V, then the value of I = 5A

Note! When specialists operate with large dimensions P, they use kilowatts (kW), 1 kW = 1000 W

How many amperes in 1 watt

The current value determines the amount of charge passing through a certain surface area of ​​the conductor over a certain period of time. The current is measured in amperes, and to convert this value into watts, you should use the following formula.

I=P/U

I - current strength (ampere);

P - power (watt or kilowatt);

U - voltage (volts).

To find out how many amperes are in one kilowatt, just substitute the values, taking the voltage within the standard limits of 220 V.

1000 W / 220 V = 4.54 A

Typically, the value of the rated current of a single-phase network is taken for calculations. It is calculated by the formula:

I = 4.5 × P

P - power consumption (kW).

You can convert watts to amperes using this formula very quickly, although the resulting value will have some error.

Examples of calculations

Below are practical applications of the calculations. Several options are being considered.

Approximate conversion of kVA to kW

How to convert watts to amperes

In this case, the result is obtained with a small error that can be neglected.

20% is subtracted from the useful power S, and active P is obtained. If we take 1 kVA, then 20% of it will be 0.2 kVA. Therefore, 1– 0.2 = 0.8. This means that for a quick approximate translation it is enough to multiply this value by 0.8. For example, S = 300 kVA, which means P = 300 * 0.8 = 240 kW.

Approximate conversion of kW to KVA

In this case, you need to do the opposite - add 20%, which means dividing by 0.8. Let P = 200 kW, which means S = 200/0.8 = 250 kVA.

Exact translation formula for converting kVA to kW

To convert kVA to kW, you can use a formula that looks like this:

P = S*cosϕ,

Where:

• P – active power, kW;
• S – total, kVA (kva);
• cosϕ – coefficient.

This way you can convert any apparent power values ​​into an active value.

Formula for converting kW to kVA

You need to translate in reverse order by changing the formula:

S=P/ cosϕ.

All parameters included in it are already known.

Attention! An electricity meter, installed to measure the amount of energy consumed, calculates how many kilowatts per hour are supplied to the electricity subscriber. If the subscriber uses reactive type consumers for his needs, he will pay for full power. It will be greater than its practically spent active value.

Passport data displayed on devices

Of practical importance for ordinary citizens, the difference between these two values ​​is significant only when purchasing instruments and devices. Not all manufacturer-designated data indicate both values ​​at once. To understand exactly what power a particular device will produce, you need to be able to convert one value into another.

Power in sports

Performance can be assessed using power not only for machines, but also for people and animals. For example, the power with which a basketball player throws a ball is calculated by measuring the force she applies to the ball, the distance the ball travels, and the time over which that force is applied. There are websites that allow you to calculate work and power during exercise. The user selects the type of exercise, enters height, weight, duration of exercise, after which the program calculates the power. For example, according to one of these calculators, the power of a person 170 centimeters tall and weighing 70 kilograms, who did 50 push-ups in 10 minutes, is 39.5 watts. Athletes sometimes use devices to measure the power at which muscles work during exercise. This information helps determine how effective their chosen exercise program is.

Dynamometers

To measure power, special devices are used - dynamometers. They can also measure torque and force. Dynamometers are used in various industries, from technology to medicine. For example, they can be used to determine the power of a car engine. There are several main types of dynamometers used to measure vehicle power. In order to determine engine power using dynamometers alone, it is necessary to remove the engine from the car and attach it to the dynamometer. In other dynamometers, the force for measurement is transmitted directly from the car wheel. In this case, the car's engine through the transmission drives the wheels, which, in turn, rotate the rollers of the dynamometer, which measures engine power under various road conditions.

This dynamometer measures the torque as well as the power of a vehicle's powertrain.

Dynamometers are also used in sports and medicine. The most common type of dynamometer for these purposes is isokinetic. Typically this is a sports trainer with sensors connected to a computer. These sensors measure strength and power of the entire body or specific muscle groups. The dynamometer can be programmed to issue signals and warnings if the power exceeds a certain value

This is especially important for people with injuries during the rehabilitation period, when it is necessary not to overload the body

According to some provisions of the theory of sports, the greatest sports development occurs under a certain load, individual for each athlete. If the load is not heavy enough, the athlete gets used to it and does not develop his abilities. If, on the contrary, it is too heavy, then the results deteriorate due to overload of the body. The physical performance of some exercises, such as cycling or swimming, depends on many environmental factors, such as road conditions or wind. Such a load is difficult to measure, but you can find out with what power the body counteracts this load, and then change the exercise regimen, depending on the desired load.

Author of the article: Kateryna Yuri

Voltage measurement

Voltage measurement plays an important role in fundamental physics and chemistry, applied electrical engineering and electrochemistry, electronics and medicine, and in many other branches of science and technology. It is perhaps difficult to find branches of human activity, excluding creative fields such as architecture, music or painting, where voltage measurements would not be used to control ongoing processes using various types of sensors, which are essentially converters of physical quantities into voltage. Although it is worth noting that in our time these types of human activities cannot do without electricity in general and without voltage in particular. Artists use tablets that measure the voltage of capacitive sensors when a stylus is moved over them. Composers play electronic instruments that measure the voltage on the key sensors and, depending on it, determine how hard a particular key is pressed. Architects use AutoCAD and tablets, which also measure voltage, which is converted into a numerical form and processed by a computer.

A kitchen thermometer (left) measures the temperature of meat by measuring the voltage across a resistive temperature sensor through which a small current is passed. In a multimeter (right), temperature is determined by measuring the voltage directly across the thermocouple

The measured voltage values ​​can vary widely: from fractions of a microvolt in studies of biological processes, to hundreds of volts in household and industrial devices and appliances, and up to tens of millions of volts in ultra-powerful particle accelerators. Voltage measurement allows us to monitor the condition of individual organs of the human body by taking encephalograms

brain activity.
Electrocardiograms
and
echocardiograms
provide information about the condition of the heart muscle. Using various industrial sensors, we successfully, and most importantly, safely, control chemical production processes, which sometimes occur at extreme pressures and temperatures. And even nuclear processes at nuclear power plants can be controlled by measuring voltages. Using stress measurements, engineers monitor the condition of bridges, buildings and structures and even withstand such formidable natural forces as earthquakes.

A pulse oximeter, like a voltmeter, measures the voltage at the output of a device that amplifies the signal from a photodiode or phototransistor. However, unlike a voltmeter, here on the display we see not the voltage value in volts, but the percentage of hemoglobin saturation with oxygen (97%).

The brilliant idea of ​​connecting different values ​​of voltage levels with the state values ​​of units of information gave impetus to the creation of modern digital devices and technologies. In computing, a low voltage level is interpreted as a logical zero (0), and a high voltage level is interpreted as a logical one (1).

In fact, all modern computing devices are, to one degree or another, voltage comparators (meters), converting their input states according to certain algorithms into output signals.

Among other things, accurate voltage measurements form the basis of many modern standards, the implementation of which guarantees their absolute compliance and thus safety of use.

The memory board used in personal computers contains tens of thousands of logic gates.

How to use

To convert current into power, it is enough to enter the nominal voltage and indicate the second known value. The calculator will automatically calculate the unknown indicator and display the result.

You can find out the voltage and standard current in the technical documentation of the device. For household appliances, the power is usually indicated, from which the current is also easy to calculate. For convenience, in the calculator you can switch watts to kilowatts, and amperes to milliamps.

Read further:

Calculation of electrical power during repair and design

Kilowatt to horsepower conversion calculator

Car engine power calculator

Calculator for converting pressure in bar to pressure in megapascals, kilograms of force, pound of force and atmospheres

Battery discharge time calculator

Differences

Active power is measured in kilowatts, and total or nominal power is measured in kilovolt amperes. Volt ampere with kilovolt ampere, being a power unit of current, is calculated as the product of current ampere values ​​​​in an electrical circuit and the volt voltage at its ends. A watt per kilowatt is the energy accomplished per second and is equal to one joule. The measurement is carried out using the force of constant energy at a volt voltage.

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Note! Only a part of the device’s power is involved at the time of work activity. The rest comes out.

How do the values ​​differ?

Power units

Power is measured in joules per second, or watts. Along with watts, horsepower is also used. Before the invention of the steam engine, the power of engines was not measured, and, accordingly, there were no generally accepted units of power. When the steam engine began to be used in mines, engineer and inventor James Watt began improving it. To prove that his improvements made the steam engine more productive, he compared its power to the performance of horses, since horses had been used by people for many years, and many could easily imagine how much work a horse could do in a certain amount of time. In addition, not all mines used steam engines. On those where they were used, Watt compared the power of the old and new models of the steam engine with the power of one horse, that is, with one horsepower. Watt determined this value experimentally by observing the work of draft horses at a mill. According to his measurements, one horsepower is 746 watts. Now it is believed that this figure is exaggerated, and the horse cannot work in this mode for a long time, but they did not change the unit. Power can be used as a measure of productivity because as power increases, the amount of work done per unit of time increases. Many people realized that it was convenient to have a standardized unit of power, so horsepower became very popular. It began to be used in measuring the power of other devices, especially vehicles. Although watts have been around for almost as long as horsepower, horsepower is more commonly used in the automotive industry, and many consumers are more familiar with horsepower when it comes to power ratings for a car engine.

60 watt incandescent lamp

What are watt and volt

1 volt is equal to a unit of voltage created by an electric current at the ends of a conductive device designed to produce 1 watt of heat at a constant electrical characteristic passing through the conductor. The volt characteristic is also defined as the potential difference between two measured points when a charge of one coulomb moves from point A to point B, when work of 1 joule is required.

Volts, watts and amps

1 W is an indicator of power at which work equal to 1 J is performed per second. It turns out that W is considered a derivative of two quantities. Power and voltage have a relationship:

1W = 1V*1A

Formulas

To have an idea of ​​what power is, you need to think logically. If we assume that it is simply force, such a conclusion will be incorrect. To correctly evaluate a physical quantity, it is enough to know that power is the rate at which a device consumes energy.

For example, a lamp can produce bright or dim light, depending on the rate at which energy is consumed. If the brightness is higher, then the consumption is higher, and vice versa.

Attention! The power rating applies to all electrical appliances, but it is not always related to electricity. This is the main difference between the indicators

Basic current values

Power also comes in:

• Thermal – determined by temperature parameters.
• Electrical – the indicator is taken into account in electrical appliances, including light bulbs.
• Mechanical, determined by the number of horsepower.

All of the above refers to physical characteristics.

What is the difference between W and V (V and A)

What is the difference between a volt and an ampere: Volt is a unit of measurement of voltage, and watt is a unit of power. V is the difference created in the electrical potential across a wire line when a current of 1A dissipates a unit of power, i.e. voltage. The definition of voltage is that it is the potential of electricity between different points. Along with this, it is used to indicate the difference in potential energy of an electric charge between points. An energy source is a voltage that represents expended or lost energy.

About power

Attention! Voltage is hypothetically similar to the pressure created in a circuit, pushing electrons through.

The passage of current must be ensured on two paths. This characteristic is considered the total energy for moving the charge. The definition of voltage is based on the fact that negative charges are attracted to high values, and positive charges to low values.

W – speed of work. The speed is maintained at 1 meter per second against a constant reaction force of 1 newton. If we consider it in relation to electromagnetism, the unit is the rate of work done when 1 ampere passes through a potential difference of 1V. Watt is a measure of power.

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Power

Power is the energy flow with which energy is consumed. It happens that in the description of a device it appears instead of kW - kVA. To determine this value, you need to know what is measured in kVA.

No energy is expended to complete the work, but on the contrary:

• One of the factions becomes active, that is, it performs work or transforms into another form.
• The other faction is reactive. The energy is directed into an electromagnetic field.

Attention! These quantities are different, despite the same proportionality. To avoid confusion, the indicator is measured not in watts, but in volt-amperes.

Mechanical power

How to convert volt-amperes to watts

Having figured out what VA is, you need to consider what needs to be done if you need to convert volt amperes to watts. To solve everyday problems, you can follow the following algorithm:

1. In the power supply instructions you need to find the value of the power it consumes. Often manufacturing companies indicate the value of this parameter in volt-amperes. It indicates the largest amount of electrical energy that the device is capable of consuming from the network. Thus, it can be equated to the full power value.
2. Now you need to find out the efficiency of the source being used. It is determined by the features of its design and how many devices are connected to it. In practice, this coefficient when connecting household and professional appliances usually varies between 0.6-0.8.
3. After this, the actual conversion of volt-ampere units to watt units is performed. To perform this, you need to find out the active power of the device that supplies uninterruptible power. To find out its value in watts, you need to multiply the consumed power parameter in volt-amperes, indicated by the manufacturer in the accompanying documentation, by the efficiency of the device (also known as power factor). This can be expressed using the formula: B = VA*efficiency.

The calculation method can be shown with an example. Let's say the technical data sheet of the device indicates that its power consumption is 2000 volt-amperes. The efficiency factor turns out to be 0.7. If you multiply the numbers, it turns out: 2000 * 0.7 = 1400 Watts. This number shows the active power consumption supplied by this device. The remaining 30% represents energy losses associated with the functioning of the nutritional unit.

A calculator is also used to convert va to tu. You need to fill in the fields that the screen form offers with values ​​corresponding to the indicators of a particular device, and click the button that initiates calculations. Upon completion, the user will receive the desired power value in watts.

Important! The active power value by definition cannot exceed the full power. But for a certain part of electric current consumers (for example, incandescent light bulbs, boilers, electric kettles), these two indicators are equal to each other due to the absence of a reactive load component, therefore, when calculating related to them, there is no need to convert watts to volt-amperes or vice versa

For these devices, the power figures expressed in watts will be identical to those in volt-amperes. This means that the level consumed by the device and required for its proper functioning will be equal to the active power expressed in watts.

Power triangle

What is "volt-ampere"

Before looking at how to convert va to watts, you need to understand what va power is. Volt-ampere is a non-system measuring unit. In Russia, it is often used on an equal basis with the watt, a unit of the international SI system. Power VA is equal to the current indicators of current and voltage multiplied by each other. In writing, the measuring unit is usually shown as VA or VA. There are both submultiple and multiple units, for example, one megavoltampere contains a million VA. Such a unit is designated as MV·A, in professional speech it is called “emva”. A kilovolt-ampere is equal to a thousand VA. As a rule, subdivisions are not used in practice.

Important! Sometimes VA is mistakenly equated to total power or treated as a unit absolutely equivalent to a watt. This is an error associated with the identification of a certain quantity and its dimension.

Total electrical power is measured in volt-amperes; this unit is used to estimate power in circuits where alternating electric current operates: under these conditions there is no need to convert it into watts, since they are equal to each other. When working with direct current, things are different: the current-voltage indicator is equated to active (rather than total) power in watts, in which case some calculations will be required to determine the power characteristics.

Why ampere?

Amperes measure the amount of current that takes its name from Henri M. Ampère, a French physicist who lived in the late 18th and early 19th centuries and dedicated his career to understanding electromagnetic phenomena. An important discovery in the study of magnetic fields created by current was that the strength of the magnetic field does not depend on the voltage, but on the strength of the current. It was this that became the basis for the scientific community in determining the strength of current, and for this reason, the quantity that measures the strength of current was called ampere. In addition, the scientist was interested in and defined other branches of physics, such as cybernetics and kinematics. He also has merits in the study of botany and philosophy.

The meaning of determining this value is that theoretically two wires are placed parallel to each other in space. They have the smallest possible cross-section and a distance from each other of 1 meter. When starting a current of 1 ampere through each of them, the interaction between the wires will be equal to a force of 2 * 10 to minus 7 powers of Newton. A certain number of electrons will pass through each wire, this is 6.2415092 * 10 to the 18th power.

In order to understand how many amps there are in other electrical circuit units, there are related relationships of ampere and volt, ampere and watt, and ampere and ohm. When a voltage of 1 volt is applied to a wire having a resistance of 1 ohm, a current of 1 ampere will flow through it, and a power equal to 1 watt is also released on the wire as heat. Electrical quantities are used in all countries of the world with the same meaning.

Ratios of electrical units in a system (SI)

What is power Watt [W]

Power is a quantity that determines the ratio of work performed by a current source over a certain period of time. One watt corresponds to one ampere times one volt, but kilowatt/hour is used to determine energy costs.

It corresponds to the consumption of one thousand watts for 60 minutes of operation. It is by this indicator that the cost of electricity services is determined.

In most cases, the power consumed by the device is indicated in the technical documentation or on the packaging. The specified quantity is produced in one hour of work.

To help determine the current strength at a known power, a calculator will help, which converts one physical quantity to another.

Watt, kilowatt and kilowatt-hour

The unit of measurement watt got its name in honor of the scientist James Watt, who studied electricity in the nineteenth century. It is he who is credited with the invention of the universal steam engine.

Today, any power is measured in watts, not just electrical power. For example, to measure the power of a car engine, watts are also used along with horsepower. However, most often it is not the “watt” itself that is used, but its derivative, the kilowatt (kW). By analogy with the meter and kilometer, as well as with the gram and kilogram, one kilowatt is equal to a thousand watts.

Energy is often also calculated in other units, multiples of the watt. For example, to measure high power it is convenient to use the megawatt, a unit that corresponds to a million watts. You can also use other prefixes of the international system of units, including those that correspond to tenths, hundredths, thousandths.

For example:

• deciwatt is a tenth of a watt;
• centiwatt - its hundredth part;
• A milliwatt is a thousandth of a watt.

The electric power that is consumed by ordinary household appliances such as lamps, refrigerators, and TVs is best measured in kW. If the watt and its derivative units are included in the SI system, then the kilowatt-hour is not there. KWh is a unit of measurement that is non-systemic. It was created only to keep track of the electrical energy produced or, conversely, used.

The use of kWh on the territory of the Russian Federation is regulated by GOST, which clearly indicates the name, designation and area in which it is used. A kilowatt-hour can be designated either by four Russian letters or three English ones. The Russian designation is “kWh”, and the English designation is “kW h”.

Converting kVA to kW and vice versa

In layman's terms, the difference between kW and kVA is that kW is useful and kVA is total power. According to the following example of converting values ​​kVA-20%=kW and 1=0.8 kW. To convert ampere to kW, subtract twenty percent from the first value. The result will be an indicator with a small error. For example, if a household stabilizer has a power of 15, then to calculate kilowatts, you need to multiply this value by 0.8 or subtract 20% from it. Then you can recalculate everything using online converters. As a result, you need to follow a simple formula:

P=S * Cosf, where P is the active power, S is the apparent power, Cos f is the power coefficient.

Conversion formula

To reverse the action and calculate kilovolts, for example, on a 10 kilowatt portable generator, you need to divide this value by 0.8, according to the formula below:

S=P/ Cos f, where S is considered the total power, P is the active force, and Cos f is the power coefficient. More detailed background information is given in any physical textbook, including the answer to the question of how to convert the power of a 1000 kVA transformer into kW.

Formula for converting kW to kVA

It is worth noting that the most common interpretations of the power coefficient are the following values: 1 is the optimal value, 0.95 is good, 0.90 is satisfactory, 0.80 is average, 0.70 is low and 0.60 is bad. Therefore, converting the power of a 1000 kVA transformer into kilowatts is not difficult.

Power coefficient values

Answering the question what is the difference between kilowatt and kilovolt, we can say that these are two different quantities. In the first case, this is a unit of measurement for total power, and in the second, only active power. Their difference is manifested in the operation of electrical equipment, despite the possible similarity in the writing of quantities.

The essence of the phenomenon

In a DC circuit, 1 VA is the equivalent of one watt (1 W). Power (P) (in watts) in a DC circuit is equal to the product of voltage (V) in volts and current (I) in amperes: P = VI

Volt-amps

In an AC circuit, power and V•A mean the same thing when there is no reactance. It is introduced when the circuit contains an inductor or capacitor. Since most AC circuits contain reactance, the V•A value is greater than the actual power dissipated or delivered in watts. This can cause confusion regarding power supply specifications.

For example, the power supply may be rated at 600 V•A. This does not mean that it can output 600 watts if the equipment has no reactance. In real life, the P rating of a power supply is 1/2 to 2/3 of the actual V•A.

Important! When purchasing an uninterruptible power supply for use with electronic equipment, including computers, monitors, and other peripherals, you must ensure that the V•A specifications for the equipment are used in determining the minimum ratings for it. V•A is nominally 1.67 times (167%) more watts consumed

Power

Errors when calculating V•A

The ratios of volt amperes and watts for certain types of electrical appliances and devices, for example, light bulbs, are identical. But when talking about computers, watts and V•A will be different, but V•A will always be greater than or equal to watts. The gap is related to power factor (PF), which varies among devices. If you do not take it into account, then when selecting equipment elements an error will be made and they will not fit the main device.

If we consider the choice of a UPS for a personal computer, and on the passport data the rating is indicated in voltamper, this will make it difficult to select a rating in W. When there are no exact indicators of P, do the following - the load data indicated on the nameplate is taken equal to 60% of the V•A indicator of the UPS.

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Online calculator

Additional Information. In order to more accurately determine the data, you can use an online calculator. Some websites provide the user with the required P if they click on the device type, such as TV or desktop. These sites often show graphical charts that make it easy to measure the V•A of various appliances, from refrigerators to computers.

It can be concluded that V•A is an important characteristic for modern electrical devices and equipment. If this indicator is not taken into account when purchasing electrical devices, they will operate in overload mode, which will lead to their premature failure.

How to convert watts to amperes - instructions.

The formula we need looks like this:

P=I*U

The following indicators are used here:

• P – power (W),
• I – current strength (A),
• U – network voltage (V – volts).

Regarding voltage, we note that in a household electrical network, the voltage in the most common single-phase lines is 220 V.

As in any other formula, knowing two indicators out of three, the last third indicator (“unknown”) is very easy to find. Based on the question posed at the beginning, we need to find the current strength (amps), knowing the power (watts). Therefore, the above formula will be transformed into the following form: I=P/U.

A small example is a problem about how watts are converted to amperes and why.

There is a kitchen. There is a group of sockets in the kitchen. This entire group of sockets is turned off by an automatic switch in the electrical panel, which has the designation 16A. The following appliances are connected to the sockets in the kitchen: microwave (1000 W), electric kettle (2000 W), oven (1500 W). The question is: will the line hold up if all these devices are turned on at the same time?

Solution.

Having a 16A circuit breaker, we must assume that this data will serve as the limiting value for us; the current strength in this section of the circuit should not exceed 16A. First, we add up the powers, and in total we get 4500 watts. Next, according to our formula, we obtain the current strength (amps): 4500/220 = 20.45 A. Accordingly, if you turn on the electric kettle, microwave and oven at full power, then the 16A safety circuit breaker will simply “knock out”.

Hence the conclusion: it is very useful sometimes to think about how to convert watts into amperes, and then apply the calculations in practice, especially during repairs, for example, to lay (as in our example) an additional electrical line that allows you to distribute the load along different wires, or to relay the line using other wires designed for higher current.

How to measure power in volt-amps

Before you convert volt-ampere (V•A) into amplifiers, you need to understand what these measurements are. The current-voltage characteristic is an apparent measure of power, while the ampere is a measure of current.

Volt-ampere characteristics

So to convert between them you need to use the formula:

Power = Voltage × Current Using the P formula as a starting point and modifying it, you can convert power to V•A: I (A) = power (V•A) : voltage (V) For example, you need to calculate amplifiers for a single-phase electrical circuit with P = 1800 V•A at 120 volts. I (A) = 1800 V•A : 120 volts I (A) = 15 A

Thus, a circuit with 1800 VA apparent power at 120 volts has an I rating of 15 amps.

Converting VA to current for a three-phase electrical circuit is slightly different. For the calculation, a modified three-phase formula is used.

I (A) = Power (V•A) : (√3 × Voltage (V))

For a three-phase electrical circuit, I in amperes is equal to the power in volt-amps divided by the square root of three.

Reactive power in VAR

For example, you need to find amplifiers for a three-phase electrical circuit with P = 33,255 V at a voltage of 480 V.

I (A) = 33,255 V•A : (√3 × 480 V) I (A) = 33,255 V•A : 831.38 VI (A) = 40 A It can be seen that a circuit with an apparent power of 33,255 V •A at 480 V will have a nominal I = 40 A.

Quick conversion table for dBm to volts and watts into a 50 ohm load

It will be useful to many radio amateurs as a reference sheet, especially to those who are involved in designing, tuning and measuring the parameters of radio receiving equipment. Similar tables have already been published in various literature, but an attempt was made to generalize and place everything on one sheet. I and many of my friends printed this table on a printer and became convinced of its usefulness.