Phase controller for processing current and voltage faults

摘要

A power supply system for processing current and voltage faults is disclosed. Each phase of a first power source (12) and each phase of a second power source (28) has a pair of switches (60, 64) for controlling the conduction of current from the phase of the power source to a phase load (29). In each of the phases of the first power source (12), a first switch (60) is controlled by a first control signal which has a high level when a voltage fault or current fault condition does not exist. When either a voltage fault or a current fault condition exists, the first switch (60) is turned off. The second switch (64) is turned on by a second control signal during a determination of whether a current fault exists. Furthermore, a logic network causes the first control signal to assume the second level in response to any one of an RMS over/under voltage fault, an instantaneous overcurrent fault, an I2t fault, or an instantaneous voltage fault occurring in the phase to which the switches are connected or in any one of the other phases in the first power source. Upon the detection of a voltage fault condition, the first power source (12) is disconnected from the load and a second power source is connected to the load. All of the phases of the first power source are disconnected either immediately in response to the detection of a fault in any one of the phases or, alternatively, the phase with the fault is immediately disconnected and the remaining phases without a fault are disconnected at the zero current crossing points of the AC signal of the phases. The phases of the second source are connected at a point when the voltage of the phase is zero.