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How can you maintain a constant 13.5 volts DC at 20 amps even though the circuit will demand more amps as the temperature increases?
Wiki User
∙ 14y ago
If the question asks how 13.5 volts can be supplied to a device that draws 20 amps (nominally), the supply responds to the setpoint selected (13.5 volts). The supply's voltage has the ability to actually change as the dynamic resistance of the device it supplies changes. That's weird because we want the voltage to stay the same. The supply is actually changing the amount of current it supplies as the resistance of the load changes, and this will keep the applied voltage fixed at 13.5 volts. How does that work? We know that for a given resistance, if we wish to supply a constant voltage, we will get a fixed amount of current draw. As the resistance changes (goes down) due to thermal effects, the supply will actually deliver more current to maintain the 13.5 volts. In this way, the supply can accomplish voltage regulation. It's classic Ohm's law. The volts equals the current times the resistance. If voltage is to remain constant, then the current times the resistance will have to remain constant. The onlyway this can happen is that as resistance goes down, current must go up. As the device heats up and its dynamic resistance decreases, the current it "demands" to keep the supplied voltage at the 13.5 volts goes up. The supply does all this automatically.
Wiki User
∙ 14y ago
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