| 摘要 |
A unit for ground of the neutral in three-phase network consists of a voltage transformer, the second winding of which with help of a relay front contact is loaded on a coil of vacuum contactor, thee bunches of low-voltage resistors connected in series accordingly with “star“ circuit, beam of which are connected to phases of 3-6 kV network, and an amplifier, input of which is connected between null point of “star” and ground. The relay front contact is connected between the neutral with power resistor connected to it and ground. The amplifier is made with limit output with insert 1,3-1,4 times exceeding amplitude of phase network, which with help of diode is connected to input of a single-shot multivibrator. Output of the single-shot multivibrator with help of pair of single-directed diodes is connected to base resistor of transistor, which is loaded with a relay, and resistor of time –setting RC-circuit. Between connection point of resistor with RC-circuit condenser and connection point of base resistor with diode it is connected emitter-base junction of the other transistor having collector connected to relay supply source. Charge time of RC-circuit condenser does not exceed time of being single-shot multivibrator in quasi-stable state. |
