For those who do not like mathematics or do not remember some of the basic concepts they learned in primary and secondary school, it can be difficult to understand the exact meaning of certain units in the International System of Units.
Terms such as volts, kVA and watts are often used in the marketplace to express certain technical characteristics of electronic products, and knowing what they mean can make it easier to compare one electronic product with another.
For example, you don't need to be computer literate to buy an electric inverter generator, as the companies concerned are always willing to do the calculations for you.
But if you know what each term means, you can make the first draft when calculating your needs.
This article explains the differences and what volts, kVA and watts are used for, so that, you can better calculate your energy needs:
Volt: Unit of Electrical Voltage
Let's first explain what a volt is. It is a unit of measurement in the International System of Units used to define electrical voltage or difference in electrical potential.
It is named after Alessandro Volta, the inventor of the volt cell, which can be considered the precursor of the electric battery.
The technical explanation is that one volt (always denoted by the symbol "V") corresponds to the transfer of potential energy (measured in joules) divided by an electric charge (measured in coulombs) between two different points. Confused? Let's calm down and simplify.
If we say that the voltage between two points is 1 volt that means that each coil of charge moving through space carries 1 joule of electricity.
In short, if you've read anything about electrical voltage, you should know that it's expressed in volts. Many people call it volt, but the technically correct term is always voltage.
KVA: Knowledge About Kilovolt Amperes
KVA values are also well known to the general public. If you want to buy a generator, for example, you will probably come across this unit of measurement, since the power of circuit breakers and generators is usually measured in kVA.
KVA is a unit of measurement equal to 10³ volt-amps (or 1000 VA in decimal form). VA is short for volt-ampere, which is nothing more than the apparent power of a power source. Two other quantities are included here: active power (measured in watts) and reactive power (watts).
For those of you who like math, the mathematical formula that expresses voltage power is as follows: VA² = W² + var². The power factor is another basic requirement for the optimal operation of the power grid and the consumers.
Let us consider an example to illustrate this point. Suppose we are operating with a 3 kVA grid and a power factor of 0.85.
In this case, we should use the following formula: VA x PF = W. If we substitute this figure in our example, we get 3000 VA x 0.85 = W. This means 2550 W or 2.55 kW.
However, there are other factors to consider for proper sizing of the generator. An applications engineer should be consulted to provide the customer with the best possible solution.
Watt: Power Measurement
Finally, to complete the list of explanations, we have Watt. It is expressed by the symbol "W" and is the unit of power defined in the International System of Units. The value 1 watt is equal to one joule per second.
And why does it have this name? Simply because it is another tribute to a great scientist in our history.
James Watt, a Scottish mathematician and engineer who lived between 1736 and 1819, was one of the main people responsible for perfecting the steam engine. His methods made the industrial revolution possible on such a scale.
Incidentally, there is a remarkable story worth telling. At that time, any work that required labour was done with horses, and James Watt, wanting to find a way to measure it in a steam engine, decided to compare the results directly with the number of horses needed to do the work.
This led to the measurement of horsepower (hp), which is still used today to express the power of an automobile engine. Thus, 1 horsepower is equal to the power required to lift a 75 kg load to a height of 1 metre in one second. If we transfer this information to the world of energy, 1 hp equals 735.5 watts.
In short, a watt is a measure of power that expresses the ability of electricity to do work. We also have a "kilowatt" prefix to indicate 1000 watts. In other words, 5 kW equals 5,000 watts, and the prefix "mega" is used for 1 million watts. Therefore, 5 million watts corresponds to 5 MW.
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