Voltage Regulators

Voltage regulators are electronic devices that are used to provide a steady voltage. Depending on its basic design a voltage regulator might be electromagnetic or it may have passive and active electronic components to perform the task. A voltage regulator can regulate AC and DC voltages. Except for shunt regulators, most voltage regulators compare the output voltage against an internal reference voltage. If there is any difference between the two voltages, the voltage regulator will automatically compensate to provide the right output. The regulation element in a voltage regulator will start producing more or lesser voltage depending on a low or high output voltage reading. The task of the voltage regulator is to make sure the voltage stays as close to the prefixed level as possible. This induces two variables, the speed of response of the voltage regulator and its stability.

The alternators and automobile generators from the old days used a mechanical voltage regulator the employed 1-3 relays and resistors in order to stabilize the generator output. This was kept between 6-12 volts and was not dependent on the engine RPM or the load on the vehicle. The relays worked on the principle of pulse width modulation to function as voltage regulators. The regulators that were fixed on generators were also cut off when the generator was not working so that the batteries would not discharge back through the generator.

Modern designs of voltage regulators use solid-state technology, transistors, to work exactly the way vacuum tubes did. Electromechanical voltage regulators are also used to regulate the voltage of power lines. This type of voltage regulator will simply select the right tap on a given transformer. If there is any fluctuation in voltage, the tap changer will switch the connection to provide a higher voltage. This way the tap changer keeps track of low and high variations in voltage to maintain a stable output.

The controls for such a voltage regulator also include a dead-band. The dead-band is basically a range within which the voltage will be permitted to fluctuate. This is provided so that the voltage regulator is not constantly switching taps because small-scale variations are inevitable.

A voltage stabilizer is basically a voltage regulator that is used in homes to output a constant voltage even if the backend power supply fluctuates for any reason. A voltage stabilizer uses a servomechanism, also know as a negative feedback, that helps control the tap position. The tap moves in the opposite direction of the voltage value. A lowering in voltage will cause it to step up voltage and vice versa.

The only other way to maintain constant voltage is use a type of transformer known as the ferroresonant transformer. This type of transformer uses a tank circuit and a capacity that slowly drains out voltage at a constant value. This transformer is good because it has no active components in it. The tank circuit simply absorbs whatever fluctuations might result in the voltage while the capacitor offers the most stable form of output voltage.