RU4170U1 - DC TRANSFORMER SENSOR FOR RELAY PROTECTION - Google Patents

Abstract

1. A transformer DC sensor for relay protection, comprising a current transformer with an air gap in the magnetic circuit with a first electronic thyristor relay connected to its secondary winding and powered by an operative DC voltage and consisting of diodes, a zener diode or a dynistor, a thyristor, a tuning resistor and an intermediate relay characterized in that a second electronic thyristor relay is additionally introduced, also connected to the secondary winding of the current transformer, like the first electronic relay, h cut diodes, but with opposite polarity, and both electronic relays are connected to the operational constant voltage via their parallel-connected opening contacts of the intermediate relays, the second contacts of each of these relays are connected to the tuning resistors of the other electronic relay, and the third are the closing contacts of each of these relays connected in series with the fourth - NC contacts of another relay and form two sensor output circuits. 2. The sensor according to claim 1, characterized in that when installed in a single-sided circuit, one contact of each intermediate relay is used, while both electronic relays are connected to the operative constant voltage through the opening contact of the second relay, and one output circuit of the sensor is formed by the closing contact of the first relay.

Description

The utility model relates to test equipment and can be used for relay protection against short circuits (short circuit) in DC systems, in particular, in operational DC circuits of power plants and substations. A common DC sensor is a relay connected to a shunt installed in the DC circuit C. Installing a shunt that reduces reliability is not required when using a direct current measuring transformer containing a current transformer with an air gap in the magnetic circuit, a Hall sensor and an electronic amplifier 21. An electronic relay is connected to the amplifier output. However, the need to use a Hall sensor and connect an additional power source to the measuring transformer complicates the design of the sensor and its mounting technology, which makes the product more expensive. μm G01R 5/00 Transformer DC sensor for relay protection

To simplify the design of the sensor and its installation, only a current transformer with an air gap in the magnetic circuit with an electronic relay connected to it can be used. Such a transformer sensor, called a pulse relay, can respond to the absolute increment (surge) of the current 31. A thyristor electronic relay usually contains semiconductor gate diodes, a zener diode or a dynistor, a thyristor, a tuning resistor, and an intermediate relay C1; 4. The pulse relay has a simple design. Only an electronic relay with two wires is connected to the current transformer, which simplifies the installation of the current transformer. However, a transformer sensor-pulse relay provides fixation of only one information sign of short-circuit - the value of short-circuit current. Other informational signs - the polarity and duration of the short-circuit current, necessary for using the sensor as part of centralized protection, are not recorded, which is a drawback of the pulse relay.

The pulse relay in technical essence and the achieved results is the closest to the claimed utility model and can be considered as a prototype.

The purpose of the utility model is to increase the amount of information received from a transformer DC sensor during short circuits, i.e. fixing not only the short-circuit current value, but its polarity and duration of passage.

This drawback is eliminated by the fact that a second electronic thyristor relay is additionally connected, connected to the terminals of the secondary winding of the current transformer, like the first relay through diodes, but with opposite polarity, and both relays are connected to the operational constant voltage through their parallel open contacts, the second contact each of these relays is included in

the tuning resistor circuit of another relay, and the third - the closing contacts of each relay are connected in series with the fourth - opening contacts of the other relay and form two sensor output circuits.

When using the sensor in a DC circuit with one-way power supply, where the polarity of the short-circuit current is known, in order to simplify the circuit, one contact of each relay is used, while both electronic relays are connected to the operational constant voltage through the NC contact of the second relay, and the sensor output circuit is formed closes the contact of the first relay.

The essence of the utility model is illustrated in the drawing, where Fig. 1 is a circuit diagram of a transformer DC sensor, and Fig. 2 is a simplified circuit diagram of a sensor for a single-sided DC circuit, FIG. 3 and 4 are timing diagrams of the sensor operation at short-circuit currents of direct and reverse polarities. A timing diagram of the operation of the sensor with a simplified circuit in a one-way supply circuit corresponds to FIG. 3 with a time chart 10 shown by a dashed line (relay 10 without deceleration upon return). The positions in the drawing indicate:

Current transformer - I with primary winding - 2, magnetic core - 3 with air gap and secondary winding - 4; electronic thyristor relay - 5 with diodes - 6, zener diode - 7, tuning resistor - 8, thyristor - 9, intermediate with delay when the relay returns - 10 with contacts - 10.I, 10.2, 10.3, 10.4; the second electronic thyristor relay - II with diodes - 12, a zener diode-13, a tuning resistor - 14, a thyristor-15, intermediate with a delay when the relay 16 is returned with contacts - 16.I, 16.2, 16.3, 16.4; . sensor output circuits 17 and 18. In FIG. 3 and 4: current in the primary winding of the current transformer i, in the secondary winding - (2In Fig. I, the current transformer I is connected by the primary winding 2 to the controlled DC circuit with two-way power supply. Magnetic circuit 3 has an air gap to prevent DC loading of the load. Conclusions the secondary winding 4 is connected to an electronic thyristor relay 5, consisting of diodes 6, a zener diode 7, a tuning resistor 8, a thyristor 9 and an intermediate relay 10. A second electronic thyristor relay II of the same design as 5 is also connected to the outputs of the secondary winding 4, but through the diodes 12 with the opposite polarity than the diodes 6. The supply of both electronic thyristor relays is carried out from the source of operational direct current (+), (-) through the parallel contacts IO.I and 16.I of the intermediate relays 10 and 16. The second contacts of the intermediate relays 10.2 and 16.2 are included in the circuit of the tuning resistors of another relay, respectively, 14 and 8. The third - the closing contacts of each relay 10.3 and 16.3 are connected in series with the fourth - the opening contacts of the other relay, respectively, 16.4 and 10.4, forming two output circuits 17 and 18 of the sensor. The circuit of FIG. 2, intended for monitoring direct current in a one-way supply circuit, where the polarity of the short-circuit current is known, differs from the circuit of FIG. I using only one contact for each intermediate relay. Through the opening contact 16.I of the second intermediate relay, both electronic thyristor relays are powered from the operative direct current (+), (-) source, and the making contact 10.I of the first intermediate relay without deceleration 10 forms one sensor output circuit - 17. Operation illustrated by timing diagrams of FIG. 3 and FIG. 4. With a direct polarity of the short-circuit current (Fig. C) from the first - positive pulse of the secondary current C2, the first electronic thyristor relay 5 and its intermediate relay 10 are activated. With this contact 10.3 closes the first output circuit of the sensor 17, and the signal about the occurrence of a short-circuit with direct the polarity of the current is supplied to the subsequent links of the relay protection. Open contact 10.I is bridged by closed contact 16.I, through which the power supply of both electronic relays continues; closing the contact 10.2 in the circuit of the tuning resistor 14 of the second relay II changes its setting, and the contact 10.4 additionally opens the second output circuit 18. After switching off the short circuit, the second electronic thyristor relay II and its intermediate relay 16 are activated from the negative pulse of the secondary current 2 Opening the contact I6.I leads to the return of both relays 10 and 16, and the opening of contact 16.4 - to remove the signal on the circuit 17. The duration of the signal on the circuit 17 is equal to the duration of the short circuit. Chain 18 does not close. With the reverse polarity of the short-circuit current (Fig. 4) from the first - negative pulse of the secondary current i, the second electronic thyristor relay II and its intermediate relay 16 are activated. With this contact 16.3 closes the second output circuit of the sensor 18, and a signal about the occurrence of a short-circuit with reverse polarity of the current fed to the subsequent links of relay protection. Open contact 16.I is bridged by closed contact 10.I, through which the power supply of both electronic relays continues; opening contact 16.2 in the circuit of the tuning resistor 8 of the first relay 5 changes its setting, and contact 16.4 additionally opens the first output circuit 17. After the short circuit is switched off, the first electronic thyristor relay 5 and its intermediate relay 10 from a positive pulse of the secondary current i contact 10.1 leads to return both relays 16 and 10, and opening contact 10.4 - to remove the signal on circuit 18. The duration of the signal on circuit 18 is equal to the duration of the short circuit. Chain 17 does not close. The values of the operating currents of the electronic thyristor relays 5 and II can significantly differ due to the use of tuning resistors 8 and 14 with different resistance and different contacts in their circuit, for example, closing 10.2 and breaking 16.2. This determines the various fixed values of the short-circuit currents of direct and reverse polarity. The polarity of the short circuit current is determined by the output circuit along which the signal passes, 17 or 18. The signal duration along the corresponding circuit 17 or 18 is equal to the short circuit duration. This ensures the informational advantage of the proposed transformer DC sensor for relay protection compared to the prototype, which consists in additional fixing the polarity of the short circuit current, its duration and different values of the short circuit current at different polarities. The operation of the device with a simplified circuit designed to fix the short circuit and its duration in a circuit with one-sided power supply is similar to that described above for the direct polarity of the short circuit current. The advantage of the proposed utility model in comparison with analogue 2 is the same as that of the prototype 3. In the utility model, the simplest current transformer is included in the direct current circuit, possibly of an overhead design that does not require an additional power source, which simplifies and cheapens the product and its installation in an electrical installation. The utility model provides relay protection with almost the same information on the short-circuit mode as with

using analog 23

Sources of information

1.Glukh E.M., Zelenov V.E. Protection of semiconductor converters.- M .: Energoizdat, 1982, p. 107-108.

2.Ermlsch J. Betrachtugen zum Elnsatz neuartigen WandlerX / Elektrle 38, 1984. H.6. S. 219-222.

3.Figurnov E.P. Relay protection of railway power supply devices. Textbook for high schools. d. transp. - M .: Transport, I98I. S. 182-184.

4.Zasypkin A.S., Dyakov A.F., Levchenko I.I., Taramaly B.D. Relay protection of the rectifying installation of ice melting / ХElectric stations, 1975,) 1 II. S. 79-80.

The authors:

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Zasypkin A.S.

Kotlov M.M.

Lunin L.S.

Claims (2)

1. A transformer DC sensor for relay protection, comprising a current transformer with an air gap in the magnetic circuit with a first electronic thyristor relay connected to its secondary winding and powered by an operative DC voltage and consisting of diodes, a zener diode or a dynistor, a thyristor, a tuning resistor and an intermediate relay characterized in that a second electronic thyristor relay is additionally introduced, also connected to the secondary winding of the current transformer, like the first electronic relay, h cut diodes, but with opposite polarity, and both electronic relays are connected to the operational constant voltage via their parallel-connected opening contacts of the intermediate relays, the second contacts of each of these relays are connected to the tuning resistors of the other electronic relay, and the third are the closing contacts of each of these relays connected in series with the fourth - NC contacts of another relay and form two output circuits of the sensor.  2. The sensor according to claim 1, characterized in that when installed in a single-sided supply circuit, one contact of each intermediate relay is used, while both electronic relays are connected to the operative constant voltage via the opening contact of the second relay, and one output circuit of the sensor is formed by a closing contact of the first relay.