How to convert amperes to kilowatts: principles of conversion and practical examples with explanations
Amperes and kilowatts are characteristics of the electricity consumed by devices connected to the network. The first is also called load, and the second is called power.The need for translation arises at the stage of selecting protective devices, the markings of which most often indicate only the current strength.
You will learn everything about how to convert Amperes to Kilowatts from our proposed article. We will look at the theory, understand the basic principles of translation, and then explain the meaning of these actions using practical examples. By following our advice, you can perform such calculations yourself.
The content of the article:
Reasons for making a transfer
Power and current are key characteristics necessary for the proper selection of protective devices for equipment powered by electricity. Protection is needed to prevent melting of the wiring insulation and breakdown of units.
Electrical wiring supplying lighting, an electric stove, and a coffee machine must be protected by individually selected devices. After all, each consumer creates “its own” load - in other words, consumes a certain current.
By the way, the cables and wires that supply the listed household devices have a certain current-carrying capacity. The latter is dictated by the cross-section of the cores.
Each protective device must operate at the moment of a voltage surge that is dangerous for the type of equipment being protected or a group of technical devices. So, choose RCD and the machines should be so that during a threat to a low-power device, the network is not completely disconnected, but only the branch for which this jump is critical.
On buildings offered by the retail chain circuit breakers a number is indicated indicating the maximum permissible current. Naturally, it is indicated in Amperes.
But on the electrical appliances that are required to protect these machines, the power they consume is indicated. This is where the need for translation arises. Despite the fact that the units we are examining belong to different current characteristics, the connection between them is direct and quite close.
Voltage is the potential difference, in other words, the work put into moving a charge from one point to another. It is expressed in Volts. Potential is the energy at each point where the charge is/was.
Current strength refers to the number of Amperes passing through a conductor in a specific unit of time. The essence of power is to reflect the speed at which the charge moved.
Power is indicated in Watts and Kilowatts. It is clear that the second option is used when an overly impressive four- or five-digit figure needs to be reduced for ease of perception. To do this, its value is simply divided by a thousand, and the remainder is rounded up as usual.
Powering high-power equipment requires a higher rate of energy flow. The maximum permissible voltage for it is higher than for low-power equipment. The machines selected for it should have a higher operating limit. Therefore, accurate selection according to the load with competent conversion of units is simply necessary.
Transfer rules
Often, when studying the instructions included with some devices, you can see the power designation in volt-amperes. Experts know the difference between watts (W) and volt-amperes (VA), but practically these quantities mean the same thing, so there is no need to convert anything here. But kW/hour and kilowatts are different concepts and should not be confused under any circumstances.
To demonstrate how to express electrical power in terms of current, you need to use the following tools:
- tester;
- current clamps;
- electrical reference book;
- calculator.
When converting amperes to kW, use the following algorithm:
- Take a voltage tester and measure the voltage in the electrical circuit.
- Using current measuring keys, measure the current strength.
- Recalculation is carried out using the formula for direct voltage in the network or alternating.
As a result, the power is obtained in watts. To convert them into kilowatts, divide the result by 1000.
We also have material on our website about the rules for converting Amperes to Watts. To get acquainted with it, please go to following link.
Single phase electrical circuit
Most household appliances are designed for a single-phase circuit (220 V). The load here is measured in kilowatts, and the AB marking contains amperes.
The key to translation in this case is Ohm's law, which states that P, i.e. power is equal to I (current strength) multiplied by U (voltage). We talked in more detail about the calculation of power, current and voltage, as well as the relationship between these quantities in this article.
It follows from this:
kW = (1A x 1V) / 1 0ᶾ
But what does this look like in practice? To understand, let's look at a specific example.
Let's say the automatic fuse on an old type meter is rated at 16 A. In order to determine the power of devices that can be safely connected to the network at the same time, you need to convert amperes to kilowatts using the above formula.
We get:
220 x 16 x 1 = 3520 W = 3.5 kW
The same conversion formula is used for both direct and alternating current, but it is only valid for active consumers, such as incandescent lamp heaters. With a capacitive load, a phase shift necessarily occurs between current and voltage.
This is the power factor or cos φ. While when there is only a resistive load this parameter is taken as one, when there is a reactive load it must be taken into account.
If the load is mixed, the parameter value fluctuates in the range of 0.85. The less the reactive component of power is, the smaller the losses and the higher the power factor. For this reason, they strive to increase the last parameter. Manufacturers usually indicate the power factor value on the label.
Three-phase electrical circuit
In the case of alternating current in a three-phase network, take the value of the electric current of one phase, then multiply it by the voltage of the same phase. What we get is multiplied by cosine phi.
After calculating the voltage in all phases, the data obtained is added up.The amount obtained as a result of these actions is the power of the electrical installation connected to the three-phase network.
The basic formulas are as follows:
Watt = √3 Ampere x Volt or P = √3 x U x I
Ampere = √3 x Volt or I= P/√3 x U
You should have an understanding of the difference between phase and linear voltages, as well as between linear and phase currents. In any case, the conversion of amperes to kilowatts is carried out using the same formula. An exception is the delta connection when calculating loads connected individually.
On the cases or packaging of the latest models of electrical appliances, both current and power are indicated. With this data, we can consider the question of how to quickly convert amperes to kilowatts resolved.
Experts use a confidential rule for circuits with alternating current: divide the current strength by two if you need to roughly calculate the power in the process of selecting ballasts. The same is done when calculating the diameter of conductors for such circuits.
Examples of converting amperes to kilowatts
Converting amps to kilowatts is a fairly simple math operation.
There are also many online programs where you just need to enter known parameters and press the appropriate button.
Example No. 1 - converting A to kW in a single-phase 220V network
We are faced with the task: to determine the maximum power permissible for a single-pole circuit breaker with a rated current of 25 A.
Let's apply the formula:
P = U x I
Substituting the values that are known, we get: P = 220 V x 25 A = 5,500 W = 5.5 kW.
This means that consumers whose total power does not exceed 5.5 kW can be connected to this machine.
Using the same scheme, you can solve the issue of selecting the wire cross-section for an electric kettle consuming 2 kW.
In this case I = P : U= 2000 : 220 = 9 A.
This is a very small value. You need to seriously consider the choice of wire cross-section and material. If you give preference to aluminum, it will withstand only light loads; copper with the same diameter will be twice as powerful.
We discussed in more detail about choosing the required wire cross-section for home wiring, as well as the rules for calculating the cable cross-section by power and diameter in the following articles:
- Wire cross-section for home wiring: how to calculate correctly
- Calculation of cable cross-section by power and current: how to correctly calculate wiring
- How to determine the cross-section of a wire by diameter and vice versa: ready-made tables and calculation formulas
Example No. 2 - reverse transfer in a single-phase network
Let's complicate the task - we will demonstrate the process of converting kilowatts into amperes. We have a certain number of consumers.
Among them:
- four incandescent lamps each 100 W;
- one heater with a power of 3 kW;
- one PC with a power of 0.5 kW.
Determining the total power is preceded by bringing the values of all consumers to one indicator; more precisely, kilowatts should be converted into watts.
The heater power is 3 kW x 1000 = 3000 W. Computer power - 0.5 kW x 1000 = 500 W. Lamps - 100 W x 4 pcs. = 400 W.
Then the generalized power is: 400 W + 3000 W + 500 W = 3,900 W or 3.9 kW.
This power corresponds to the current strength I = P : U = 3900W : 220V = 17.7 A.
It follows from this that you should purchase a machine designed for a rated current of no less than 17.7 A.
The most suitable for a load of 2.9 kW is a standard single-phase 20 A circuit breaker.
Example No. 3 - converting amperes to kW in a three-phase network
The algorithm for converting amperes to kilowatts and in the opposite direction in a three-phase network differs from a single-phase network only in the formula. Let’s say you need to calculate what maximum power a battery with a rated current of 40 A can withstand.
We substitute known data into the formula and get:
P = √3 x 380 V x 40 A = 26,296 W = 26.3 kW
A three-phase 40 A battery is guaranteed to withstand a load of 26.3 kW.
Example No. 4 - reverse transfer in a three-phase network
If the power of the consumer connected to a three-phase network is known, the current of the machine is easy to calculate. Let's say there is a three-phase consumer with a power of 13.2 kW.
In watts it will be: 13.2 kt x 1000 = 13,200 W
Next, the current strength: I = 13200W: (√3 x 380) = 20.0 A
It turns out that this electrical consumer needs a machine with a nominal value of 20 A.
For single-phase devices, there is the following rule: one kilowatt corresponds to 4.54 A. One ampere is 0.22 kW or 220 V. This statement is a direct result arising from the formulas for a voltage of 220 V.
Conclusions and useful video on the topic
About the connection between watts, amperes and volts:
The relationship between amperes and kilovolts is described by Ohm's law. Here there is an inverse proportionality of the strength of the electric current in relation to the resistance. As for voltage, there is a direct dependence of the current on this parameter.
Do you still have questions about the principle of converting Amperes to Kilowatts or want to clarify the nuances of practical calculations? Ask your questions to our experts in the comments block located below the article.
If you have useful information that complements the material presented above, or clarifications, corrections, write your comments and additions below.
kW = (1A x 1 V) x 1 0ᶾ - must be divided by 1000, not multiplied.
That's what it says there.