POWER LOAD UNBALANCE DETECTION CIRCUIT

PURPOSE:To eliminate the possibility of malfunctioning a power load imbalance detection circuit, by supplementing a reclosing no-voltage time detection circuit to the power load unbalance detection circuit. CONSTITUTION:A power load unbalance detection circuit detects the generator current as the generator output. It also detects the intermediate vapor pressure as the input energy from a turbine. When the decreasing rate of generator current exceeds 40%/10m sec and its decreasing range 40%/10mm sec, a power load unbalance relay 16 actuates. So does a vapour governor 2. At the same time, a bypass valve 3 is closed so abruptly as to shift to an inhouse isolated operation in a power station. During reclosing no-voltage period the condition to turn OFF from a transmission line protective relay device 12 is given to the power load balance detection circuit as a locking condition, by which the shift to the unnecessary inhouse isolation operation can be prevented.