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Standby power, also called vampire power [1], vampire draw, phantom load, ghost load, or leaking electricity, refers to how electronic and electrical appliances consume electric power. At the same time, they are switched off (but are designed to draw some power) or in standby mode. It only occurs because some devices claim to be "switched off ...
In the event that an abnormal high-current power draw is detected, the switched-mode supply can assume this is a direct short and will shut itself down before damage is done. PC power supplies often provide a power good signal to the motherboard; the absence of this signal prevents operation when abnormal supply voltages are present.
When a group of customers sharing the neutral draw unequal phase currents, the common neutral wire carries the currents resulting from these imbalances. Electrical engineers try to design the three-phase power system for any one location so that the power drawn from each of three phases is the same, as far as possible at that site. [25]
Alternating-current electric motors and transformers may draw several times their normal full-load current when first energized, for a few cycles of the input waveform. Power converters also often have inrush currents much higher than their steady-state currents, due to the charging current of the input capacitance.
Toasters typically draw 2 to 10 amps at 110 to 260 volts consuming around 600 to 1200 watts of power. Power systems deliver energy to loads that perform a function. These loads range from household appliances to industrial machinery. Most loads expect a certain voltage and, for alternating current devices, a certain frequency and number of phases.
Power supplies label their total power output, and label how this is determined by the electric current limits for each of the voltages supplied. Some power supplies have no-overload protection. The system power consumption is a sum of the power ratings for all of the components of the computer system that draw on the power supply.
In low-voltage conditions the UPS will use more current than normal, so it may need a higher current circuit than a normal device. For example, to power a 1000 W device at 120 V, the UPS will draw 8.33 A. If a brownout occurs and the voltage drops to 100 V, the UPS will draw 10 A to compensate.
In an electric power system, a harmonic of a voltage or current waveform is a sinusoidal wave whose frequency is an integer multiple of the fundamental frequency.Harmonic frequencies are produced by the action of non-linear loads such as rectifiers, discharge lighting, or saturated electric machines.