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rayleighconnect™ collects many electrical energy parameters including power.

What is power?

Electrical power is the rate at which electrical energy is transferred or converted from one form to another. It is a measure of how quickly electrical work is done or how quickly electrical energy is consumed or produced in an electrical circuit or device. Power is a fundamental concept in electricity and is essential for understanding the performance and efficiency of electrical systems.


Electrical power is defined as the product of voltage (V) and current (I) in an electrical circuit. Mathematically, it is expressed by the formula:

P = V * I


  • P is the power in watts (W).
  • V is the voltage in volts (V).
  • I is the current in amperes (A).


The standard unit of electrical power in the International System of Units (SI) is the watt (W). One watt is equal to one joule per second, representing the rate at which energy is transferred or converted. Other commonly used units of power include kilowatts (kW), megawatts (MW), and gigawatts (GW), where 1 kW = 1000 W, 1 MW = 1,000,000 W, and 1 GW = 1,000,000,000 W.

Relationship with Energy

Power and energy are related but distinct concepts. While power represents the rate of energy transfer or conversion, energy is the total amount of work done or energy transferred over a period of time. Electrical energy (E) can be calculated by multiplying power (P) by the time (t) over which the power is consumed:

E = P * t


  • E is the energy in watt-hours (Wh) or kilowatt-hours (kWh).
  • P is the power in watts (W).
  • t is the time in hours (h).

Types of Power

There are three types of electrical power.

Real Power (Active Power)

Real power is the actual power consumed by a device or system to perform useful work, such as lighting, heating, or operating machinery. It is measured in watts (W).

Reactive Power

Reactive power is the power that oscillates between the source and the load due to the presence of inductive or capacitive elements in the circuit. It does not perform useful work but is necessary for the operation of certain types of equipment, such as motors and transformers. Reactive power is measured in volt-amperes reactive (VAR).

Apparent Power

Apparent power is the combination of real power and reactive power in an electrical system. It represents the total power flow in the circuit, including both the useful power consumed and the reactive power required by inductive or capacitive loads. Apparent power is measured in volt-amperes (VA) and is calculated as the product of voltage (V) and current (I) without considering phase differences. It is important for sizing electrical equipment, such as transformers and circuit breakers, to ensure they can handle the total power demands of the system.


Understanding electrical power is crucial for designing, analyzing, and optimizing electrical systems for efficiency, reliability, and performance. It allows engineers and technicians to determine the power requirements of devices, calculate energy consumption, and ensure that electrical systems operate safely and effectively.