PURPOSE: To provide a highly reliable ground phase which an arithmetic processing can detector easily be conducted in that can decides a ground phase accurately even if a phase of a zero-phase voltage changes due to an earth resistance at the time of grounding.
CONSTITUTION: This device is provided with line voltage generating devices 33-35 which find line voltages Vbc, Vca and Vab respectively from each of three phase voltages Va-Vc and shift the specified amount of the line voltage and then output it, calculating devices 45-47 which calculate a scalar product of each of the line voltages Vbc, Vca, Vab and a zero-phase voltage Vo, and a comparing device 48 which compares the outputs obtained from the calculating devices 45-47 and decides the practically largest phase is an earth phase.
MATSUMURA KOICHI
ISHIBASHI KOJI
SHIRAISHI KIICHI
TOHOKU ELECTRIC POWER CO
| JPS6439301A | 1989-02-09 |