SU1005238A2 - Device for protecting three-phase electric network from incomplete-phase operation modes - Google Patents

Description

(5) DEVICE FOR PROTECTION AGAINST IMPOSSIBLE OPERATING MODES OF THE THREE-PHASE ELECTRIC NETWORK

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This invention relates to relay protection and emergency control technology in electrical installations.

According to the main auth. No. 951538, a device for protection against incomplete-phase modes of a three-phase electrical network, containing mode control sensors installed on both sides of the protected object, is known, while the mode control sensor on the supply side is designed as an antenna filter of zero-sequence voltage, on the load side, in the form of a reverse voltage voltage filter 15, a zero voltage voltage filter output. connected to the first input relay of the actuator, an output voltage filter about via the integrating and threshold unit connected to the input of the second input relay of the executive unit C 1

The inclusion of a reverse sequence voltage of the integrating unit at the output of the voltage filter and the output of the integrating unit at the output of the integrating unit allows increasing the reliability of power supply in non-phase-phase operation modes. In this case, the threshold limit of the threshold organ can be selected taking into account the maximum allowable heating of the electric motors.

In the event of a break in 10 kV networks, due to the capacitive and inductive nature of these networks, overturning of the phase alternation may occur. In this case, the motors change the direction of rotation, which will lead to heavy technological consequences for consumers. Also, with a cliff on. In the TS itself, the voltage of the direct sequence at the start of the electric motor is equal to the voltage of the negative sequence and, as a result, the start of the electric motor is generally impossible. However, the device selected as a prototype in this case leaves the electric motor in operation until it reaches a critical temperature, which ultimately reduces the service life of the electric motors.

The object of the present invention is to increase the reliability of the protection operation.

To achieve this goal, in the device for protection, from the incomplete-phase modes of operation of the three-phase electric network, aut. ff 951538 additionally, on the load side, a direct sequence voltage filter is installed, the outputs of the indicated direct sequence voltage filter and the negative sequence voltage filter are connected to the inputs of the newly introduced comparator unit, the output of the comparator unit is connected to the second input of the second input relay. The drawing shows a diagram of the device being described. In the device, on the side of the supply line 1, there is an antenna filter 2 of the voltage of the null sequence, after the control object 3, on the load side, the filter 5 is installed. reverse sequence voltage and direct voltage voltage filter 6. The signal from the antenna filter 2 of the zero-sequence voltage is fed to the input relay 7, the signal from the filter-5 negative sequence voltage flows through the integrating unit 8 and the threshold element 9 to the first input of the second input relay 10 and the comparison unit 11. The second input voltage filter 6 is connected to the second input of the comparator unit 11. The output of the comparator unit 11 is connected to the second input of the second input relay 10 "The contacts of the first and second input relay 7, 10 are connected to the power supply circuit of the first 12 coils and the third 13 output relay, In addition, the opening contact k of the input relay 10 is connected between the output of the antenna 4) Iltra zero-sequence voltage and ground. The device works as follows about “5 times. In the non-phase mode, caused by a break in the control object 3, for example, due to a high-voltage fuse blown, a signal appears on the voltage filter 5

Claims (1)

reverse sequence. The magnitude of this signal depends on the ratio, the motor load and the active one and is primarily determined by the load on the electric motor. If the magnitude of the load of the motor's narwhal is small, then the magnitude of the output signal is small (the effect of rimmetrization and replenishment of the rest of the load). If the magnitude of the load on the motor shaft is large, then the magnitude of the signal at the output of the voltage filter about the e-atom sequence is significant. Therefore, in the device, the signal from the filter 5 of the negative sequence voltage is integrated by block 8 and at the output of the integrating block 8 the signal is proportional to the integral of the input signal. When the value of this signal reaches the set value, the threshold organ 9 is triggered, as a result, the input relay 10 is triggered. The signal on the antenna filter 2 of the zero-sequence voltage is absent in this case, so the relay 7 does not trigger. When the relay 10 trips, its contacts close and the coil of the output relay 13 is energized. Relay 13 is activated, which means an incomplete phase mode caused by an interruption in the control object. When the supply line wire is broken, a signal from the antenna filter 2 of the zero-sequence voltage and the filter 5 of the negative-sequence voltage appear. The signal from the reverse-sequence voltage filter is integrated by block 8, when the actuation value of the threshold organ 9 is reached, the latter is triggered and the input relay 10 receives power. The operation of the relay 10 leads to the opening of the contact 1A, as a result, the input relay 7 is activated and the winding of the output relay 12 receives power. Relay 12 is triggered, which means a broken wire supply line. In addition, in the case of an incomplete phase and inoperative motors, the magnitude of the negative sequence voltage is equal to or greater than the value of the direct voltage. In this case, the comparison unit 11 is triggered and the signal is fed to the input relay 10, the integrating unit 8 and the threshold organ 9 mine. The device then operates as described above. In the event of a wire break on the line side and the order of phase alternation overturns, the device also affects the output relay 13 without a time delay, since in this case the reverse sequence voltage is greater than the voltage of the forward Sequence. Thus, the inclusion of a direct-sequence and comparison filter allows to significantly increase the reliability of power supply in non-phase-phase operation modes. This eliminates the possibility of starting electric motors in non-phase-mode operation, if the voltage in the sequence does not exceed the reverse sequence voltage or their equality . The invention The device for protection against incomplete-phase modes of operation of a three-phase electrical network according to the author. ff, which is different from the fact that, in order to increase the reliability of protection, on the load side, a direct sequence voltage filter i the outputs of the specified voltage sequence filter and a reverse sequence filter are connected to the inputs of the newly entered comparison unit , the output of the block is compared to the second input of the second input relay. Sources of information taken into account during the examination 1. USSR Author's Certificate No. 951538, cl. H 02 H S / 10, H 02 H 3/16, 10.30.80.