Low-tension side load change manner null of the transformer between the bank which

摘要

PURPOSE:To shorten load switching time by opening primary cutout of one bank in a state that a first switch is closed, and then closing a static switch, a second switch of a switching circuit when voltage drop of one bank is detected. CONSTITUTION:A switching circuit Sa of a switching device S is connected in series with normally open relay contacts S1U-S1W as a first switch corresponding to phases of power distribution lines U-W and overload preventive resistors RU-RW. Triacs 1-3 as static switches and relay contacts S2U-S2W as normally open second switches are connected in parallel. Primary cutouts PCU-PCW of one bank are opened. Then, when a voltage drop of the opened phase is detected, the switches 1-3 and the switches SU2-SW2 are conducted to switch loads.