Electrical power is an important aspect of any electrical and electronic circuits. In this article, we will discuss all about Electrical power and its significance.
What is Electrical Power
In general science power is simply defined as the capacity to do work. In other words, it is defined as the rate of doing work. Whereas In electrical engineering, Electrical power is the rate per unit of time at which the amount of electrical energy is transformed into some other form of energy (such as heat, light, mechanical power, etc.). Electrical power is one of the key concepts associated with Electrical Engineering.
Mathematically, Electrical power is defined as the product of voltage drop across the electrical element in the circuit and current flowing through it. It is measured in terms of Electrical Energy per unit time.
Units of Electrical Power
When we talk about Electrical Power then it is considered as Active power consumed by the circuit element. So the unit of Electrical power (Active power) is Watt or joule per second.
Watt is the SI unit of the power which is defined as the rate of conversion of 1-joule electrical energy per unit second.
Hence the Power consumed in an electrical circuit is said to be 1 watt if one ampere current flows through the circuit when a potential difference of one volt is maintained across it.
1 kW = 1000 Watt
Types of Electrical Power
- DC Power: Power consumed in the DC circuit is known as DC power. It is produced by a fuel cell, batteries, DC generators, etc. Mathematically DC power is defined as the product of voltage and current through the circuit.
So, P = V * I
- AC Power: The electrical power associated with an AC circuit is known as Complex Power. Whereas Complex Power is the combined form of Active, Reactive, and Apparent Power in AC circuits. So AC power or complex power is further divided into three parts.
- Active Power
- Reactive Power
- Apparent Power
Active Power (kW)
the circuit. Whereas in the case of an AC circuit, it is calculated as:
Reactive Power (kVAR)
The power associated with reactive components (Inductors and Capacitors) of the circuit is known as Reactive Power. It flows in both ( back and forth) directions of the circuit. Reactive power is not a useful power for consumers so it is interpreted as wattless power. It represents an extra burden on the electricity supply system and on the consumer’s bill. This is required in the circuit to produce the electric and magnetic field for the working of capacitors and inductors in the circuit. It has a direct impact on the power factor of the circuit. It only exists in the electrical system when voltage and current in an AC circuit are not in phase.
A pure inductor and a pure capacitor do not consume any power in the circuit. Because in a half cycle whatever power is received from the source by these reactive components, the same power is returned to the source in the next half-cycle. Then the power that returns and flows in both directions in the circuit is known as Reactive power. This reactive power does not perform any useful work in the circuit. It is denoted by an English alphabet Q and measured in VAR, kVAR, or MVAR.
In the case of the DC circuits, there are no concepts of Reactive Power. Whereas for the AC circuit, it is calculated as:
Apparent Power (kVA):
The combination of Active Power and Reactive Power is known as Apparent Power. It is the total power of the circuit. Mathematically Apparent power is defined as the product of the root mean square (RMS) value of voltage and current irrespective of its phase angle. It is denoted by the English alphabet ‘S‘ and It is measured in kVA, MVA.
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