SU130369A1 - Device for signaling ground faults in networks with insulated or compensated neutral - Google Patents

Description

DEVICE FOR ALARM SIGNALING AT GROUND ONLINE IN NETWORKS WITH ISOLATED OR COMPENSATED NEUTRAL

 It was announced on September 16, 1959, No. 638930/24 in K, for H3o6j) eTeiiiiii l discoveries at the Council of Ministers of the USSR

Published in "Bulletin of inventions number 14 for 1960.

The present invention relates to devices for signaling ground faults in networks with an insulated or compensated neutral, made on a phase-sensitive circuit, including: a current and a zero zero successively i output polarized relay.

The proposed device differs from the known ones in that two controlled rectifying bridges are used as a phase-sensitive circuit, connected in series with two resistances, to the middle points of which a voltage is applied to the bullet sequence. In this case, the alternating current circuit of the bridges is threaded from the zero-sequence current transformer, between the midpoint of the winding of which and the common ac value of the alternating current of both bridges is a polarized relay.

Such a device performance increases its sensitivity, which is due to the high efficiency, current prices.

The drawing shows the electrical circuit of the proposed yet real estate.

The device is based on the use of a phase-sensitive circuit connected to the current and the zero-sequence voltage.

The phase-sensitive circuit contains two rectifying bridges, BI and 2, connected in series through the ballasts R s, to the middle points of which a zero-sequence control is applied. The alternating current circuit of the bridges fi and 8-2 is threaded from the zero-sequence current transformer through a PTT transient transformer. A polarized RI relay is connected between the midpoint of the winding of the transformer PTT and the common point of the AC circuit of both bridges.

No. 130369-2. The bridges B and Br play the role of a key, which, under the action of a zero-sequence voltage, includes c) working one or the other half of the secondary winding of the transformer PTT. During the positive half-period of the control voltage of the zero-sequence, the polarized RP relay will flow around one half of the transformer PTT, a. during the negative half-period - from the other. In this case, the average value of the current in the RP relay will depend on the phase shift between the current and the zero-sequence voltage. The capacitor Cj serves to reduce the vibration of the movable relay system from the variable component and to tune the relay from capacitive current surges during transients. Capacitor C and resistance R are used to shift the phase of the zero-sequence control voltage to obtain the desired angle of maximum sensitivity of the relay.

The advantage of this phase-sensitive circuit is that the power losses of current transformers are minimized. In addition, due to the use of a high-resistance coil in the RP relay and large current-limiting resistors Rg, non-identical characteristics of individual rectifiers in bridges cannot lead to incorrect relay operation. Therefore, the circuit does not require the use of trimming resistances, which contributes to an even greater increase in efficiency. current circuit.

In real circuits, depending on the resistance of the connecting wires in the circuit of current transformers and depending on the type of transformers used (TF or TZR), a different shift angle is obtained between the zero sequence current and the secondary current of these transformers. To eliminate the dependence of the angular area of operation of the device on the resistance of the connecting wires in the current transformer circuit and on the type of these transformers, power supply terminals K are changed, switching which allows changing the parameters of the zero-sequence voltage circuit.

Subject invention

A device for signaling during ground faults in networks with insulated or compensated neutral, made on a phase-sensitive circuit connected to the current and the zero sequence voltage and having a polarized relay output, characterized in that, in order to increase the sensitivity of the device by increasing efficiency As a phase-sensitive circuit, two controlled rectifying bridges were used, connected in series with two resistances, to the middle points of which a zero-sequence voltage was applied, and the alternating-current circuit of the bridges was powered by a zero-sequence current transformer, between the middle point of the winding and The common point of the AC circuit of both bridges is a polarized relay.