# What is electrical power?

Many people, when they say about such a thing aselectric power, imply some force. However, even in the school course of physics, knowledge was given that power and strength are different concepts, although they are interrelated.

The very concept of "power" means a characteristicevent. At the same time, it is possible to relate power to an object. Any physical effect can be called the action of force. Perfect work is also called the path traversed with the help of the applied force. The work done by the force in a certain time will be equal to the power. Thus, power is a physical quantity equal to the ratio of work accomplished in a certain time by a certain force to this time interval.

However, we must not forget that power is calledalso measure the energy. Therefore, we can take into account the statement that this term can also be called the change in energy in a certain system (the rate of energy conversion).

Although the above terms and definitionsconcern more mechanical energy, from this all it is possible to deduce such concept as "electric power". The product of the current and voltage is called the current power. Since this concept depends equally on voltage and current, we can say that the same electrical power is obtained both at high current and lower voltage, and at high voltages and low currents. This property is the basis for the transmission of electrical energy over long distances by means of power plants, substations, transformers (raising and lowering), switchgears and other electrical equipment.

Electric power is divided into twobasic types: reactive and active. Active power is a characteristic of the transformation of electricity into other types of energy (heat, traffic, light). The electrical power is measured in watts (watts). In everyday life, such energy is usually measured in kilowatts, and larger units, megawatts, are used in large power plants.

Reactive electrical powerelectrical load in various devices. It equals the product of the voltage drop on the operating current and the sine of the phase angle (phase shift) between the current and the voltage drop. Reactive power in reactive volt-amperes (VA) is measured.

Active power can be associated with electricalpower through such a concept as "cosine phi" - the difference between the phases of current and voltage. For most household appliances, this cosine will be approximately 0.8. For heating appliances, it is often raised to almost one.

Electric power is measured by specialdevice - wattmeter. Such a device has two windings. The first is a thick wire, connected with consumers of electricity and fixes the change in current. The second winding consists of a thinner wire and is connected in parallel to account for the voltage in the network. In power plants, the notion of "installed electric power" is often used, which is the sum of all the rated powers of all electric machines of only one type or type (for example, transformers, generators, motors).