Abstract: The present disclosure relates to a system for using load tap changing (LTC) transformers and voltage regulators (VRs) to more accurately reduce the voltage in a power transmission system. It further relates to a system for determining the operating mode for LTC transformers and VRs during reverse power flow. Corresponding methods are also disclosed. The various components of the present system, and the manner in which they interrelate, are more fully described hereinafter.

Abstract: A system for using load tap changing (LTC) transformers and voltage regulators (VR) to reduce the voltage in a power transmission system by temporarily disabling the upper band voltage and temporarily designating the bandcenter as the upper band edge voltage whereby the tap selector switches operate in set increments to reduce applied voltage to a level that is between the redesigned bandcenter and the lower band edge.

Abstract: A method for detecting the operating condition of each phase of a three-phase capacitor bank in a power distribution system, including the steps of, if the RMS neutral current is above the bank status closed setting, comparing the phase angle of neutral current (IN) with respect to voltage on one of the phases (VA, VB or VC) and sending an alarm signal when the comparison of the phase angle of neutral current with respect to the phase voltage differs appreciably from the expected phase angles.

Abstract: The present disclosure relates to a system for using load tap changing (LTC) transformers and voltage regulators to more accurately reduce the voltage in a power transmission system. It further relates to a system for determining the operating mode for LTC transformers and VRs during reverse power flow. Corresponding methods are also disclosed. The various components of the present system, and the manner in which they interrelate, are more fully described hereinafter.

Abstract: A method for detecting the operating condition of each phase of a three-phase capacitor bank in a power distribution system, including the steps of, if the RMS neutral current is above the bank status closed setting, comparing the phase angle of neutral current (IN) with respect to voltage on one of the phases (VA, VB or VC) and sending an alarm signal when the comparison of the phase angle of neutral current with respect to the phase voltage differs appreciably from the expected phase angles.

Abstract: An apparatus and method for measuring the source-side line voltage from a source potential transformer (PT) of a regulator during reverse power flow. A reverse power regulation algorithm is employed during reverse power operation of the tapchanger to energize a contact relay which switches the analog voltage input from the load side to the source side of the regulator. Voltage regulation then operates based on the measured source side voltage instead of the traditional calculation of the source side voltage based upon the load-side voltage and regulator type.

Abstract: In industrial complexes and power stations a main source of power is connected to a motor bus to which motors and other loads are connected. In such systems an auxiliary source of power is provided to alternatively provide electric energy to the motor bus should the main source of power be interrupted. In the prior art digital system, samples are taken of the motor bus and auxiliary system voltage waveform with a fixed time window to predict the proper time for closing the breaker. The present invention improves on the prior art by applying the concept of an adaptive time window wherein the number of samples taken during each cycle to obtain the operating parameters is increased as the frequency decreases. This provides more accurate parameters for calculating the point for closing.

Abstract: A microcontroller-based tap-changer controller including apparatus for keeping track of an electrically closed tap position and for automatically changing the tap setting of load tap-changing transformers and regulators; the tap-changer controller further utilizes the "keep-track" tap position to calculate the source voltage of the regulator for reverse power operations; and, a method for paralleling tap-changing transformers and regulators utilizing the circulating current of the units.

Abstract: A circuit for controlling a load tap changing transformer including a true RMS to D.C. converter for regulating the output of the transformer as a function of the RMS voltage.

Abstract: In a typical power system, a motor bus is fed by a main power system; and, an auxiliary system is provided to alternatively feed the motor bus. When a fast transfer from the main power to the auxiliary power system is desired, for example, in case of fault occurring in the main system, the inventive method transfers power in a synchronous mode; that is, power is transferred from the auxiliary system to the motor bus when the phase difference of the auxiliary system with respect to the frequency of the residual voltage on the motor bus is essentially zero degrees.

Abstract: Power transfer relay circuitry is disclosed for providing synchronous transfer of power such as from an auxiliary source or system to a motor or motor bus; the circuitry effects the transfer of power when the phase difference between the motor bus and the auxiliary power source is very nearly zero degrees.