RU50057U1 - THREE PHASE VOLTAGE VOLTAGE SENSOR - Google Patents

Abstract

The utility model relates to electrical engineering, in particular, to the field of automated electric drive and converter technology. A three-phase network voltage disappearance sensor containing ballast resistors, a three-phase bridge diode circuit, and a zero-organ. The zero-organ contains an optocoupler whose output is connected to the electric drive protection unit, the optocoupler LED is connected through a current-limiting resistor to the output of the smoothing filter, the input of which is connected to the zener diode anode, the zener diode cathode is connected to the output of a three-phase bridge diode circuit. By eliminating the reed relay in the null organ and introducing a zener diode and optocoupler with a current-limiting resistor into the null organ, the setup is simplified and the power consumption of the sensor is reduced. The sensor for the disappearance of voltage of a three-phase network can be used in electric drives of direct and alternating current, in a motor protection relay and other load protection equipment connected to a three-phase network.

Description

The utility model relates to electrical engineering, in particular, to the field of converting technology and automated electric drive.

A known sensor of the disappearance of voltage of a three-phase network at the input of a thyristor converter connected to the network through a circuit breaker [1]. The sensor contains a step-down single-phase transformer, the primary winding of which is connected to two phases of the input circuit of the thyristor converter, and a relay connected to the secondary winding of the transformer. If the voltage disappears in the controlled phases or the mains voltage drops below the permissible value, the relay contact opens the circuit breaker and the thyristor converter is de-energized.

The disadvantages of this solution are the control of only two phases of the network and the presence of a transformer that increases the size and cost of the sensor.

The closest in technical essence to the claimed solution and taken as a prototype is a three-phase network voltage disappearance sensor, which is part of the EPU1M series direct current electric drive manufactured by Cheboksary Electric Appliance Plant OJSC [2]. The sensor has the structure shown in figure 1, and is connected to the input circuit of the thyristor converter 1. The sensor includes ballast resistors 2 ... 4, a three-phase bridge circuit on diodes 5 ... 10 and a zero-element 11, consisting of RC filter 12 and reed relay 13. At rated voltage of all phases of the network from the output of the bridge circuit on diodes 5 ... 10 through

the filter 12 to the relay coil 13 receives a smoothed voltage with a level above the threshold of the relay, and the relay contact 13 connected to the input of the protection block of the electric drive 14 is closed. The relay contact 13 is open when the mains voltage disappears or is unacceptable. In the event of the disappearance of any phase of the network, a pulsing voltage appears at the output of the bridge circuit on diodes 5 ... 10, causing the relay 13 to switch contact. When the relay 13 contacts are opened for the first time, the protection block of the electric drive 14 gives a command to block the thyristor converter 1.

Ballast resistors 2 ... 4 are used to suppress excess voltage, the RC filter 12 is used to eliminate false alarms of the sensor when switching the thyristors of the converter 1.

The disadvantages of the prototype:

- the complexity of the sensor settings due to the inertia of the relay, the voltage spread of the relay;

- significant power losses on ballast resistors due to the large current consumption by the relay coil, which leads to the need for resistors with a large allowable power dissipation and an increase in their overall dimensions.

The technical result of the proposed solution is to simplify the configuration and reduce the power consumption of the sensor.

The technical result is achieved by the fact that in a three-phase network voltage disappearance sensor containing ballast resistors, a three-phase bridge diode circuit and a zero-organ, the latter contains an optocoupler (for example, a transistor), the output of which is connected to the drive protection unit, the optocoupler LED is connected to a current-limiting resistor to the output of the smoothing filter, the input of which is connected to the anode of the zener diode, the cathode of the zener diode is connected to the output of a three-phase bridge diode circuit.

A distinctive feature of the utility model is that simplifying the setup and reducing the power consumption of the sensor is achieved by eliminating the reed relay in the zero-organ and introducing a zener diode and optocoupler with a current-limiting resistor into the zero-organ.

The use of a zener diode that sets the threshold for the sensor, and an optocoupler with low inertia, simplifies the setup.

The decrease in the power of ballast resistors is associated with a low current consumption of the optocoupler.

Figure 2 shows a variant of the inventive sensor of the disappearance of voltage of a three-phase network, where the following notation:

1 - thyristor converter;

2 ... 4 - ballast resistors for damping excess voltage;

5 ... 10 - diodes connected by a three-phase bridge circuit;

14 - block protection electric drive;

15 - a zero-organ, consisting of a zener diode 16, an RC filter 17, a current-limiting resistor 18, optocouplers 19;

16 - zener diode;

17 - RC filter to eliminate false alarms of the sensor when switching thyristors of the Converter 1;

18 - current-limiting resistor to limit the discharge current of the capacitor of the RC filter 17 through the LED of the optocoupler 19;

19 - optocoupler.

In the proposed sensor for the disappearance of voltage of a three-phase network, the output of the optocoupler 19 is connected to the protection block of the electric drive 14, the LED of the optocoupler 19 is connected through the current-limiting resistor 18 to the output of the RC filter 17, the input of which is connected to the anode of the zener diode 16, the cathode of the zener diode 16 is connected to the output of the three-phase bridge circuit to diodes 5 ... 10, the inputs of which are connected through ballast resistors 2 ... 4 to the input circuit of the thyristor converter 1.

The operation of the sensor is as follows. With the rated voltage of all phases of the network at the output of the bridge circuit, diodes 5 ... 10 set the voltage above the threshold voltage of the breakdown voltage of the zener diode 16. The zener diode 16 breaks, and the optocoupler 19 is in a conducting state. With the disappearance or an unacceptable decrease in the voltage of the network, the zener diode 16 does not break through, the optocoupler 19 goes into a non-conductive state. In the event of the disappearance of any phase of the network in the output voltage of the bridge circuit on diodes 5 ... 10, dips appear. During these failures, the zener diode 16 does not break through, the output of the optocoupler 19 periodically goes into a non-conductive state, giving signals about the operation of the sensor. At the first signal, the protection block of the electric drive 14 issues a command to block the thyristor converter 1.

Thus, the claimed solution simplifies the configuration and reduces the power consumption of the sensor.

The proposed sensor can be used in electric drives of direct and alternating current, in a motor protection relay and other load protection equipment connected to a three-phase network.

Sources of fame:

[1] Electrical reference book. In 3 vol. T.3: In 2 kn. Book 2. The use of electrical energy / Under the total. ed. professors MPEI: I.N.Orlova (chap. ed.) and others - 7th ed., rev. and add. - M.: Energoatomizdat, 1988. - 616 p.: Ill. (See the article "Complete thyristor DC drives of the KTE series", p. 71 ... 75).

[2] Electric drives unified three-phase EPU1M series. Industrial catalog 08.41.11-99, UDC 62-83: 621.9.06 (085), GRNTI 45.4.33. p. 7 ... 12.

Claims (1)

A three-phase network voltage disappearance sensor containing ballast resistors, a three-phase bridge diode circuit and a zero-organ, characterized in that the zero-organ contains an optocoupler, for example, a transistor, the output of which is connected to the drive protection unit, the optocoupler LED is connected through the current-limiting resistor to the output of the smoothing filter whose input is connected to the zener diode anode, the zener diode cathode is connected to the output of a three-phase bridge diode circuit.