SU1359844A1 - Device for protecting three=phase electric mains against incomplete-phase operation - Google Patents

Abstract

The invention relates to the field of electrical engineering and is intended to protect electrical networks from incomplete-phase operation. In the case of a non-phase operating mode of the electrical network, a signal appears at the output f of the filter of the negative sequence voltage filter 6. This signal is integrated by the integrating unit 7. When the output signal of the unit 7 reaches the set value, the threshold element 8 is triggered and the signal enters the input of the BANCH element 9. If the load is active (for it the non-full phase mode is not dangerous), the phase angle between the current and voltage is zero or very insignificant, the signal from the high output of relay 3 and 4 The signal on the prohibiting entry of the element BAN 9 is prevented. As a result, the signal on the switching device 2 is not received. If the load is of an offset nature, there is no signal at the output of the relay 3 and 4. As a result, the signal through the element BAN 9 from the threshold organ 8 is fed to the switching device 2, and the line is turned off. 1 il. $ (L 1C with cd with 00 4 4

Description

one

The invention relates to a technique of relay protection and emergency control in electrical installations, in particular to devices for non-phase-phase operation of 10 / 0.4 kV substations, consumers of which have an active component of the load current.

is connected via the integrating unit 7 with the threshold organ 8. The output of the threshold organ 8 is connected to the permissive input of the BAN 9 element prohibiting the input of the BAN UNIT connected to the relay 3 and 4 outputs reacting to current and voltage phase shift. The output of the BANCH element 9 is connected to the commutation of power systems and is widely used by the TAILER device 2, while the power supply system is mixed, when household and industrial consumers with three-phase electric motors are connected to the same line. In the case of using this device in such networks, the reliability of power supply under non-phase-phase modes decreases, since after a time determined by the threshold setting

electrical network disconnects. with . In such mixed networks, the production load with three-phase electric motors is put into operation during the daytime, while the main domestic load has a maximum load during the evening and morning hours. For residential consumers there is no need to turn off the electrical network during non-phase-phase operation, since residential consumers do not use three-phase electric motors. As a result, if a non-full phase relays occur when only single-phase consumers or three-phase consumers operate without rotating machines,

about

For example, floor heating in livestock buildings, electric boilers, etc., then there is no need to immediately disconnect consumers. Thus, the operation of the electrical network in an incomplete-phase mode must be allowed if the consumer has an active load, and it is prohibited, if there are three-phase electric motors in the electrical network.

The aim of the invention is to increase the reliability of power supply to consumers having an active component of the load current.

The drawing shows the block diagram of the device.

The supply line 1 through the switching device 2 and two relays 3 and 4, reacting to the phase shift of the current and voltage, is connected to a consumer 5 with a mixed three-phase-single-phase load. A supply voltage filter 6 is connected to supply line 1. A sequence whose output is

13598442. . .

is connected via the integrating unit 7 with the threshold organ 8. The output of the threshold organ 8 is connected to the permissive input of the BAN 9 element prohibiting the input of the BAN UNIT connected to the relay 3 and 4 outputs reacting to current and voltage phase shift. The output of element 9 BANKS is connected to commi25

thirty

0

It is necessary to turn on two relays for different phases, since if an incomplete-phase mode occurs on the phase where the relay is installed, it can fail 15 due to lack of current.

The device works as follows.

In the case of incomplete-phase operation of the electrical network 1, a negative sequence voltage appears at the output of the filter 6. This signal is integrated by block 7, at the output of which the signal is proportional to the integral of the input signal. When the value of this signal is set;

The new value triggers the threshold organ 8 and the signal is fed to the input of element 9 BAN. Further, the operation of the device depends on the type of load of the consumer 5. If the load of the consumer 5 is active, for it is not. full-phase mode is not dangerous, the phase angle between current and voltage is zero or very insignificant considering the reactance of the power supply wires), and there are signals on the relay outputs 3 and 4 reacting to the current phase shift and voltage - cash This signal arrives at the prohibitory entry element 9 BAN. As a consequence, the signal from the threshold organ 8 to the switching device 2 is not received and line 1 is not disconnected. If necessary, an additional signal relay (for signaling or remote signaling circuits) can be switched on at the output of threshold organ 8. In case relays 3 and 4 are responsive to current phase shift

performed on principle 40

five

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five

and voltages exist. signal in the presence of a phase angle between current and voltage, the output of the indicated relays must be switched on the logical element NOT. If user load 5 is mixed, i.e. in addition to the active load, there is a motor load, or only a motor load, on the outputs of relays 3 and 4, which react

on phase shift and voltage, no signal. As a consequence, the signal from the element 9 BANCH is fed to the switching device 2 and line 1 turns off with. Preliminary calculations showed that with a 20% motor load and 80% active load, the angle between current and voltage in the non-phase mode is 17% (in normal operation 6 °), and in the motor mode 80 and 20% In the case of a household resistive load, the angle between the current and the voltage in the non-full-phase mode is 64 °. Thus, the device makes it possible to increase the reliability of power supply for mixed consumers.

Claims (1)

Invention Formula Device for protection against half-phase modes of operation of a three-phase electrical network, containing L.Povkhan editor Compiled by L.Vaskova Tehred M. Didyk Proofreader M. Pojo Order 6159/53 Circulation 618 Subscription VNIIPI USSR State Committee for inventions and discoveries 113035, Moscow, Zh-35, Raushsk nab., 4/5 Production and printing company, Uzhgorod, st. Design, 4. a reverse-sequence voltage filter, updated by the consumer, the output of which is via the integrating unit; Key to the input of the threshold organ, and a switching device, characterized in that, in order to increase the reliability of the power supply of consumers with an active component of the load current, two relays are introduced that react to the phase angle of the current and voltage, and the element BANGE, with In this case, the current inputs of the input relays serve to connect to the corresponding phase conductors of the network, and the voltage inputs serve to connect between the corresponding phase conductors of the network and the neutral conductor, allowing the input of the BANGE element to be connected to the output the threshold authority that prohibits the input is with the outputs of the indicated relays, and the output of the BANGE element is connected to the input of the switching device.