SU750635A1 - Device for differential protection of collecting bus-bars - Google Patents

Description

(54) DEVICE FOR DIFFERENTIAL PROTECTION

I

The invention relates to the differential protection of busbars of electric power systems of alternating current. .

Known about the differential protection device schine. This protection works in conjunction with current transformers having ferromagnetic mother cores. 1.

The closest in technical essence and the achieved effect is a busbar differential protection device containing current transducers installed on all busbar connections and connected in series. The common terminals of the current-voltage transducers are connected to the primary winding of an isolation transformer, the secondary winding of which is connected to the input of a full-wave rectifying bridge, with a working resistor and output.

The current transformers with their own leads, in addition, are connected to the input of a multi-phase rectifying bridge with a brake resistor at the output. The latter is connected in series with the operating resistor 2.

TIRED TRAINS

This device has a low sensitivity, as in case of a short circuit (short-circuit) in the protection circuit it has braking. In this case, the brake signal is proportional to the arithmetic sum of the currents 5 of all connections. For example, if prng nb the braking rate of protection is equal to one, then the brake signal will be equal to the differential one, i.e. to the working one. When the external short-circuit. the brake signal in this device is generated. according to another algo ° rhythm. It is proportional to the maximum current of the protection arm.

This reduces the sensitivity of the protection device and, therefore, limits its scope.

The aim of the invention is to increase

15 sensitivity differential busbar protection device.

Claims (2)

This is achieved by the fact that the device for differential protection of busbars, containing current sensors - current-voltage transducers installed on supply feeders and connected by two-wire lines to a multi-phase rectifying bridge and sensors mounted on powered feeders, connected in series and single-wire the line also connected to the said bridge, the common leads of the sensors connected in series, mounted on the supply and feed feeders are connected to the primary winding A voltage transformer, the secondary winding of which is connected via a rectifying bridge to a working resistor connected in series with a braking resistor connected to the output of a multi-phase rectifying bridge and the reacting element is equipped with two resistors and a second rectifying bridge an additional secondary winding to which a second rectifier bridge is connected with a first resistor connected by one output to the first rectifier bridge additional second resistor, and a brake operating shunt resistors and a second terminal connected to the reactant body connected to the second resistor. The drawing shows a single-line diagram of the described device for the differential protection of teams. The device contains current transformers of 1 supply feeders, current-to-voltage converters 2 fed feeders, input terminals of a differential relay 3, 4, 5, 6, 7 and 8, a multi-phase rectifying bridge 9, a voltage separation transformer 10 with two identical secondary windings, full-wave rectifier bridge 11 with operating resistor 12 at the output, braking resistor 13 connected at the output of the multi-phase rectifying bridge, reactive body 14, rectifying bridge 15 with the constant resistor 16 at the output, variable re the resistor 17. The resistances of the resistors 12, 13 and 16 are equal. The device works as follows .. Iri k.z. in prefabricated women, the voltages on resistors 12 and 13 are equal and directed oppositely. Therefore, the voltage drop across resistor 17 is zero. On the resistor 16, as well as on the resistor 12, a differential (operating) signal is allocated, which. compared with the voltage taken from the output of the resistor 17. Since in this case the voltage drop across the resistor 17 is zero, this means that for short circuit. in the zone of action of braking is absent and the sensitivity of the defense can be ensured the most. When k. 3. out of range of protection, the voltage across resistors 12 and 16 is minimal (unbalance voltage). On the resistor 13, a voltage is allocated that is proportional to the maximum current of the protection arm. Therefore, taking into account the chosen deceleration factor, a signal is removed from the resistor 17, which increases the unbalance voltage and the reacting organ does not work, and the protection does not act. Thus, the selective operation of the proposed protection device when short-circuit. in the power system is provided. Moreover, the brake signal in the device when k. in the zone (on the women) is absent, which makes it significantly more sensitive compared to the device prototype. The proposed device for differential. Collective protection can be widely applied in AC power systems due to its simplicity, reliability and high sensitivity. The calculation of the economic effect is difficult due to the lack of static data on the work of this and similar protection devices in power systems. . DETAILED DESCRIPTION OF THE INVENTION A device for a differential busbar shield containing current sensors — current-voltage converters mounted on supply feeders and connected by two-wire lines to a multiphase rectifier bridge, and sensors mounted on powered feeders connected in series by a single-wire line, also connected to the said bridge, the common leads of the sensors connected in series, mounted on the supply and feed feeders are connected to the primary winding of the separation transformer a voltage matator, the secondary winding of which is connected via a rectifying bridge to a working resistor connected in series with a braking resistor connected to the output of a multiphase rectifying bridge and reacting organ, in order to increase sensitivity, it is equipped with two resistors and a second rectifier the bridge is, and the isolation transformer is provided with an additional secondary winding, to which is connected a second rectifying bridge with the first resistor, connected m one terminal of the first rectifier bridge and a further second resistor, and a brake operating shunt resistors and a second terminal connected to the reactant body connected to the first resistor. Sources of information taken into account in the examination of t. USSR Author's Certificate No. 464040, cl. H 02 H 3/28, 1975. 2. USSR author's certificate in application number 2396688/24 07, cl. H 02 H 3/28, 1976. 1 f f rv