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However voltage spikes can also have more mundane causes such as a fault in a transformer or higher-voltage (primary circuit) power wires falling onto lower-voltage (secondary circuit) power wires as a result of accident or storm damage. Voltage spikes may be longitudinal (common) mode or metallic (normal or differential) mode.
Cause of skin effect. A main current I flowing through a conductor induces a magnetic field H.If the current increases, as in this figure, the resulting increase in H induces separate, circulating eddy currents I W which partially cancel the current flow in the center and reinforce it near the skin.
Heat sinks are often attached to portions of the circuit that produce most heat or are vulnerable to heat. Fans are also often used. Some high-voltage instruments are kept immersed in oil. In some cases, to remove unwanted heat, a cooling system like air conditioning or refrigerating heat-pumps may be required.
An AC adapter or AC/DC adapter (also called a wall charger, power adapter, power brick, or wall wart) [1] is a type of external power supply, often enclosed in a case similar to an AC plug. [2] AC adapters deliver electric power to devices that lack internal components to draw voltage and power from mains power themselves.
Overhead power lines are easiest to diagnose since the problem is usually obvious, e.g., a tree has fallen across the line, or a utility pole is broken and the conductors are lying on the ground. Locating faults in a cable system can be done either with the circuit de-energized, or in some cases, with the circuit under power.
The Type 2 connector has a maximum power output for 43 kW and can handle both single-, dual- and three-phase AC power. The IEC 62196-2 Type 1 connector (codified under SAE J1772) is the corresponding standard for single-phase AC charging in the United States, Canada, and South Korea. [12] J1772 has a maximum output of 19.2 kW. [13]
A line-interactive UPS maintains the inverter in line and redirects the battery's DC current path from the normal charging mode to supplying current when power is lost. In a standby ("off-line") system the load is powered directly by the input power and the backup power circuitry is only invoked when the utility power fails.
USB-PD Devices can request higher currents and supply voltages from compliant hosts—up to 2 A at 5 V (for a power consumption of up to 10 W), and optionally up to 3 A or 5 A at either 12 V (36 W or 60 W) or 20 V (60 W or 100 W). [61] In all cases, both host-to-device and device-to-host configurations are supported. [62]