METHOD OF RESERVE AUTOMATIC SWITCHING

FIELD: electrical engineering.SUBSTANCE: according to the method of automatic switch-on of voltage, voltage Uon consumer busbars and Icurrent are measured on the switch of infeed (SIF), connected by means of SIF to working power source. SIF position is constantly monitored by first and second position relays. Angle φ between voltage Uand current Icharacterizing loss of power supply is determined. Voltage U, current Iand angle φ are compared with the specified values and, if they exceed them, a signal for SIF disconnection is sent. Then the first busbar coupler (BC) is switched on, current Iis measured in its phases and resistance is determined by the ratio Z=U/I. Current Iis compared to preset value of current Iand resistance Zwith value of resistance Z, and if current value Iis more than or equal to specified value of current I, or Zis less than or equal to Z, signal of disconnection of the first BC is sent through time delay t. If the value of current Iis less than the specified value of current I, and Zis more than Z, then the time delay is switched to tmore than t. If after a time longer than tafter switching on the first BC circuit breaker it turns out that current value Iis more than or equal to the preset value of current Ior Zis less than or equal to Z, then in time tafter moment of current increase Iin phases of the first BC to Ior reduction of Zto Zsignal is sent to disconnect first BC. Additionally, the second BC is added to the hot standby. If after disconnection of SIF disconnection signals it is switched off and there is a signal from the first or second position relay SIF and the first BC is not connected, then the second BC is switched on. Further, immediately after switching on of second BC, current Iis additionally measured in its phases and resistance is determined by ratio Z= U/I. Current Iis compared to preset value of current Iand ratio Zwith value of resistance Z, and if current value Iis more than or equal to specified value of current I, or Zis less than or equal to Z, then time delay tis used to send signal for disconnection of second BC. If current value Iis less than preset value of current I, and Zis more than Z, time delay is switched to t. Further, if after switching on second BC it turns out that current value Iis more than or equal to specified value of current I, or Zis less than or equal to Z, then in time tafter moment of increase of current Iin phases of second BC to Ior reduction of Zto Zsignal is sent signal to discon