Input Voltage Regulation

Isolation transformers, regardless of design, do not provide input voltage regulation. They may be used for tap-switching designs, but there is no regulation ability in and of themselves.

Input voltage regulation is the forte of electronic regulators. They can accept a very wide input range, say 75 to 150 volts, and maintain an output range between 117 and 123 volts. They respond very quickly to changes on the input voltage.

Voltage regulation is also the main focus of tap-switchers. They can handle a large input swing, say 80 to 145 volts, while keeping the output voltage between 110 and 125 volts. These are not as good as an electronic regulator, but usually within the needed range of the computer or other load. Their response takes about 1 cycle, which can actually introduce problems on occasion. Tap switchers will be less effective when the voltage instability is very large.

Probably the best input voltage regulator is a Ferro. For input ranges similar to electronic regulators, the Ferro can maintain slightly better output voltage, but has a faster response time. Keep in mind the requirement for a very stable input frequency. Do not use Ferros when frequency variations occur, or on the output of other devices with unstable frequency.