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Sensitive solid-state control systems are very dependent upon their power supplies. If your control system is to operate properly, it must have accurately controlled DC voltages within specific ranges; therefore, a power supply with adequate specifications is a must.
Power supply specifications
Some common specifications for DC power supplies include the following. * Output voltage: The DC voltage or voltages the power supply produces. * Output current: The maximum current available at each of the output voltages.
* Output power: The maximum DC power drawn from the supply.
* Input voltage: The AC input voltage range over which the power supply will perform within specifications.
* Input current:The maximum current drawn from the AC input source.
* Input power: The maximum power drawn from the AC input source.
* Line regulation: The resulting variation in output voltage when input varies (usually given as a percent of output voltage).
* Load regulation: The resulting variation in output voltage when output current or load varies (usually given as a percent of output voltage).
* Ripple and noise: Peak-to-peak value of any present AC waveform superimposed on the DC output (usually given as percent of output voltage).
* Temperature coefficient: The expected variation in output voltage with changes in ambient temperature (usually given as a percent of output voltage per degree of temperature).
* Drift: The expected variation in output voltage with time, all other things held constant (usually given as a percent of output voltage and sometimes called long-term stability).
* Isolation: The electrical separation, usually given in peak volts, existing between the input and output of the power supply.
* Power factor: The expected power factor at the input of the power supply. (See the discussion below on power factor correction for more information.)
* Efficiency: The ratio between output power and input power. (The difference dissipates as heat.)
Anam of a power supply
Almost all power supplies have the same basic building blocks, as shown in the diagram. The AC input (Waveform A) passes first through a transformer that provides isolation and converts the AC voltage to a more convenient level (Waveform B). The transformed AC voltage is then rectified (converted to DC) in the rectifier (Waveform C),...