SU1723627A1 - Device for balancing of incomplete phase conditions - Google Patents

Abstract

The invention relates to electrical engineering and can be used in power supply systems for powering responsible consumers. The goal is to improve the quality of the voltage on the load at the break of one phase of the source. The device consists of three (by the number of phases) minimum voltage relays, three capacitors and three phase-shifting chokes. When one of the phases is broken, the group of contacts of the relay thus connects the load to the emergency power source, which then supplies the voltage close to the voltage of the three-phase symmetric network. 1 il.

Description

cl

with

The invention relates to electrical engineering and can be used in power supply systems for powering responsible consumers.

A device for balancing non-phase modes is known, comprising a voltage regulator, a charging device, an output transformer, a battery and a control circuit. Adding three thyristor switches to the stabilizer that act as a second control node, with a common switching node and a control circuit, makes it possible to use one power supply device for voltage stabilization and uninterrupted switching of the electrical receiver from one network to another in the event of an accident in the first, as well as switching on the inverter in case of failure of both networks. The device is characterized by a relatively high reliability of uninterrupted power supply while maintaining the high quality of the output voltage and is used to power the responsible consumers who do not suffer from interruptions in the power supply.

However, the known device is characterized by high cost, complexity of the circuit and the complexity of the settings.

The closest in technical essence to the invention is a device for balancing non-phase modes, comprising three undervoltage relays and four contactors, a three-phase asynchronous motor, a three-phase voltage relay connected to the main power supply buses, and compensating capacitors. When the voltage of one of the supply mains phases disappears, a three-phase voltage relay is activated, de-energizing the contactors coil,

VI

Yu

GO O Yu V4

whereupon the undervoltage relay is activated so that the coils of the contactors are energized and close their contacts, with a voltage applied to the terminal of the motor previously connected to the mains phase in question, fed from another phase through the compensating capacitor and the motor continues to operate.

The advantage of this device is that it provides redundancy when one phase of the mains supply is lost.

The drawback of the device is that it cannot ensure the symmetry of the three-phase voltage at the terminals of the consumers and can only be used for the capacitor mode of operation of an electric motor.

The aim of the invention is to improve the quality of the voltage on the load at the interruption of one of the source phases.

This goal is achieved by the fact that the known device for balancing non-full-phase modes, containing three phase relays of the minimum voltage of the power supply source, compensating capacitors, each of which is connected in series with the opening contact of the corresponding phase relay between the same-phase negative sequence, and terminals for connecting a three-phase load, equipped with three phase-shifting throttles, each of which is connected between the phase of the power source and the same hydrochloric terminal for connecting a three-phase load and shunted to two series-connected relay contacts zamykayu- conductive neighboring phases.

A positive effect in the proposed device is achieved by the fact that between each phase of the power source and each terminal of the same name for connecting a three-phase load there is a phase-shifting choke, shunted by two series-connected contact terminals of the relays of adjacent phases.

Fig. 1 is a circuit diagram of the device proposed; in figure 2. - vector diagrams of voltages and currents that explain the operation of the device when any phase of the power source is broken.

The device for balancing non-full-phase modes contains three phase relays 1-3 of the minimum voltage of the power source, compensating capacitors 4-6, opening contacts 7-9 of the phase relays and closing contacts

10,11,13,14,16,17 phase oel, phase-shifting inductors 12,15 and 18 terminals 19,20 and 21 for connecting three-phase load.

Phase relays 1-3 are connected between each phase of the power supply and the neutral wire, and the compensating capacitors 4-6 are connected in series with the opening contacts 7-9 between the source phases of the same name and adjacent phases of the reverse sequence. Phase-shifting inductors 12,15 and 18 of the respective phases are connected between the phases of the power supply and the like terminals for connecting a three-phase load 19-21. The phase shifting choke 12 is shunted by two serially connected make contacts 10 and 11; phase-shifting choke 15 is shunted by two serially connected make contacts 13 and 14; the phase-shifting choke 16 is shunted by a zoom of serially connected closing contacts 16 and 17.

The device operates in the following modes: the presence of voltage in all source phases, the absence of voltage in the first phase of the source, the absence of voltage in the second phase of the source, and the absence of voltage in the third phase of the source.

The device for balancing the non-phase modes operates as follows.

If there is a voltage in all phases of the power supply, the phase relays 1-3 of the minimum voltage are triggered, while their opening contacts 7-9 open and the closing contacts 10,11,13,14,16 and 17 close. As a result of the indicated switching of the current of the phases of the power supply, the terminals for connecting the three-phase load 19-21, the phase-shifting inductors 12.15 and 18, are connected, as each of them is shunted by two series-connected closed contacts of the adjacent phases. If there is no voltage in any one phase of the power source, for example, in phase A, the minimum voltage phase relay 1 does not operate and its open contact 7 is closed, resulting in a charge of the compensating capacitor 4. The current of the first phase of the device flows through the circuit : phase C of the source, capacitor 4, opening contact, closing contacts 10 and 11 and terminal for connecting three-phase load 19. The current of the second phase of the device flows through the circuit: phase B of the source, phase-shifting choke 15 and terminal for connecting tr Phase load 20. The current in the third phase of the device flows through the circuit:

phase C source, phase shifter 18, terminal for connecting three-phase load 21.

At the terminals for connecting a three-phase load 19-21, a symmetrical three-phase voltage is formed in accordance with the vector diagrams shown in Fig. 2, since the first phase current flows through the compensating capacitor 4, and the currents of the second and third phases of the device flow through the corresponding phase-shifting inductors 15 and 18. In the event of an interruption of the B-phase or C-phase of the power source, all switching circuits are carried out in a similar way, with the states of the circuit elements ensuring the operability of the device.

In the proposed device, the voltage is balanced at the load when any source phase is broken.

Claims (1)

Apparatus of the Invention A device for balancing non-full-phase modes, containing three phase relays of a minimum voltage of a power source, compensating capacitors, each of which is connected in series with the opening contact of the corresponding phase relay between the same phase of the source and the reverse phase, and terminals for connecting Three-phase load, characterized in that, in order to improve the quality of the voltage on the load with a break of one phase of the source, it is equipped with three phase separators flashing droplets, each of which is connected between the phase of the power supply and the terminal of the same name for connecting the three-phase load and is shunted by two series-connected closing contacts of the relay of the adjacent phases. ten eleven FIG. one 45 .2