Electrical Terms and Definitions
A watt is a unit of power, frequently used to define electrical power consumption. It is also used as a unit of heating power. One watt is approximately 3.41 BTU/hr. It’s important to note that a BTU is a unit of energy, while a Watt is a unit of power.
A unit of energy. The amount of power consumed over a set time period – in this case, a power of 1 watt consumed for 1 hour. A Kilowatt-hour is 1,000 watts of power exerted on a system for 1 hour and is commonly used as the basic unit of energy sold on the power grid.
Power factor is a ratio of real power to apparent power. Real power, typically measured in Kilowatts (kW), is the amount of power needed to operate a piece of equipment. Apparent power, measured in kilovolt-amps (kVA), is the amout of power present in the circuit to keep it energized. These may diverge when used to power inductive loads, such as refrigeration compressors or other large electrical motors. Poor power factor can waste significant amounts of energy and overburden electrical infrastructure.
An arc-fault circuit interrupter (AFCI) is a device intended to provide protection from the effects of arc faults by recognizing characteristics unique to arcing and by functioning to de-energize the circuit when an arc fault is detected.
A ground-fault circuit interrupter is a device intended for the protection of personnel that functions to de-energize a circuit or portion thereof within an established period of time when a current to ground exceeds the values established for a Class A device.