Abstract: A voltage regulator to provide a wide range of regulation, especially useful with process control. The regulator is provided with an extra bushing connected to the exciting winding of the regulator. By this means two or more regulators may be connected with their exciting windings in parallel and their series windings in series to provide a desired wide range of regulation. The invention also encompasses a selector switch so that the regulator operating at the top of the regulating range may be interchanged with one or more other regulators to alternate the tap-changing duty among the various regulators. Automatic operation of the regulators is disclosed.

Abstract: A control circuit for limiting the output voltage of a voltage regulator or the like to a safe level for consumers connected close to the voltage regulator. The output voltage of the regulator is measured and compared to a reference. If the voltage exceeds the preset level then the circuit is energized to prevent further tap change that would increase the voltage output. A time delay is provided to prevent immediate de-energization of the circuit when the voltage drops below the preset level. Should line fluctuations cause further voltage increase, then the circuit will cause a tap change so as to reduce the output voltage. If the output voltage drops below a preset level then the circuit will prevent further tap changing which would cause any further lowering of the output voltage.