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The current that flows through these capacitors is due to the capacitors' impedance at power line frequencies. [6] [7] Some amount of leakage current is generally considered acceptable, however excessive leakage current, exceeding 30 mA, can create a hazard for users of the equipment. In some applications, e.g. medical devices with patient ...
When the PCA can be further damaged by applying power it is necessary to use power off test techniques to safely examine it. Power off testing includes analog signature analysis, ohmmeter, LCR Meter and optical inspection. This type of testing also lends itself well to troubleshooting circuit boards without the aid of supporting documentation ...
Power semiconductor devices have a maximum power dissipation rating usually quoted at a case temperature of 25 °C (77 °F). The datasheet for the device also includes a derating curve which indicates how much a device will dissipate without getting damaged at any given case temperature, and this must be taken into account while designing a system.
Failures can be caused by excess temperature, excess current or voltage, ionizing radiation, mechanical shock, stress or impact, and many other causes. In semiconductor devices, problems in the device package may cause failures due to contamination, mechanical stress of the device, or open or short circuits.
A switched-mode power supply will be affected if the brownout voltage is lower than the minimum input voltage of the power supply. As the input voltage falls, the current draw will increase to maintain the same output voltage and current, until such a point that the power supply malfunctions or its under-voltage protection kicks in and disables ...
Thermal switches on microprocessors often stop only the fetching of instructions to execute, reducing the clock rate to zero until a lower temperature is reached, while maintaining power to the cache to prevent data loss (although a second switch, with a higher triggering temperature, usually turns off even the cache and forces the computer to ...
A switchable power strip or power bar. Timers can be used to turn off standby power to devices that are unused on a regular schedule. Switches that turn the power off when the connected device goes into standby, [30] or that turn other outlets on or off when a device is turned on or off are also available. Switches can be activated by sensors.
VESA Display Power Management Signaling (VESA DPMS) is a standard from the VESA consortium for power management of video monitors. Example usage includes turning off, or putting the monitor into standby after a period of idle time to save power. Some commercial displays also incorporate this technology.