| 摘要 |
PURPOSE:To open or close a normally open point zone switch and to energy- save by providing a cross current calculating current detecting current transformer, a cross current calculating voltage detecting transformer, a cross current value calculator, etc., installing in parallel with a normally open point zone switch, and calculating a loop cross current before a loop is operated. CONSTITUTION:A cross current calculating current detecting current transformer CT for obtaining a current value necessary when a cross current is calculated, cross current calculating voltage detecting transformers TA, TB for obtaining loop point both side voltages, a cross current value calculator for calculating a loop cross current value, etc., are provided. This cross current detection sensor LIS is installed in parallel with a normally open point zone switch LS. When the switch LS is 'open', a voltage of both sides of the normally open zone switch or a current flowing to to an impedance is measured. A function of calculating a loop cross current flowing when the switch LS is 'closed' by using the measured voltage, current, etc., is provided. Thus, a non-utility power switching can be performed only by the switching operation of the switch LS. |
