SU1361669A1 - Device for checking incomplete-phase operation of electric mains - Google Patents

Abstract

The invention relates to electrical engineering and is intended to control the non-connection of switches. The purpose of the invention is to improve the reliability of determining the location of damage in networks with high capacitive conductivity. In the case of an incomplete phase parity mode, in the control object, for example, if the contact of the switch 1 is not turned on, on the sensors 2 and 3 of the zero sequence voltage a voltage of 05 O5 O5 appears.

Description

signals of different levels, depending on the ratio of the length of the connection with a break to the total length of all connections. Signals passed through matching blocks 4 and 5 and rectifiers 6 and 7 are fed to the inputs of comparator 8, with the larger signal being sent to the direct input and the smaller signal to the inverse. The comparator 8 is activated and affects the output signal to the executive body 15. At the same time, the gate inputs of the comparators 9

The invention relates to a technique of relay protection and emergency control automation in electrical installations and can be used to control the non-connection of switches.

The purpose of the invention is to improve the reliability of determining the location of damage in networks with high capacitive conductivity.

The drawing shows a block diagram of the proposed device. The device for monitoring half-phase modes of the electrical network includes a switch 1 connection, mode control sensors, made in the form of zero-sequence voltage filters; on the supply side 2 and on the load side 3, the sensors are the star of resistance of the support insulators installed in the switchgear cells. The outputs of sensors 2 and 3 are connected respectively to blocks 4 and 5 of matching. Punching fuses or dischargers and zener diodes in blocks 4 and 5 matching prevent high voltage in the circuit when the insulator breaks across the surface, and voltage followers are introduced to match the input and output values of the signals. The outputs of each block 4 and 5 matching are connected to the inputs of the rectifiers 6 and 7, the outputs of which are connected: the output of the first rectifier 6 - with the second input of the first threshold organ, made in the form of a comparator 8, and the first

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and 10, the signal is transmitted from: KONrnapaTopa 8 through the inverter 11, which prohibits the operation of the comparators 9 and 10. When the connection phase is lost, the comparator 9 is triggered, which has a threshold lower than the comparator 10. Comparator 8 does not work, because The same signals are applied to its inputs. When a circuit to earth triggered comparators 9 and 10, the logical element And 13 and the executive body 17 of the closure to earth. 1 il.

inputs of the second and third threshold organs, made in the form of comparators 9 and 10, the output of the second rectifier 7 - with the first input of the comparator 8. The output of the last through the inverter 11 is connected to the gate inputs of the comparators 9 and 10. The output of the comparator 9 is connected to the first inputs logic elements And 12 and 13. The second input of the logic element And 12 is connected through an inverter 14 to the output of the comparator 10. The inputs of the executive bodies 15 - 17 are connected respectively to the outputs of the comparator 8 and

logical elements and 12 and 13.

The device works as follows.

In the normal mode of operation of the electrical network at the outputs of the sensors

zero sequence voltage signals are zero or due to the asymmetrical arrangement of the phase conductors with respect to the earth and the allowable inequality of leakage currents

reference insulators (current spread

isolator leakage should not exceed ± 2 µA). The device does not work.

In non-phase mode

In the control object, for example, when the contact of the switch 1 is not switched on, the signals on the sensors 2 and 3 of the zero-sequence voltage appear.

If several connections depart from the switchgear buses, the signal size is determined by the ratio of connection lengths

with a cliff to the total length of all joints. If there are four connections and if the contact is not connected, the switch contact of one of them is the signal value on the sensor 2 3U, 0.75U

about g - ts

where ICF) H is the nominal phase voltage. The signal level at sensor 3 is determined in accordance with the Zy expression, 5U (-0.5 + a2 + a) 1.5U.

Thus, on sensors 2 and 3, if the contact of the switch 1 is not turned on, signals of different levels appear. At the same time, pass units 4 and 5 of the matching and rectifiers 6 and 7 signals are fed to the inputs of the comparator 8; the larger signal is at the first input, the smaller one is at the inverse second input of comparator B. The latter is triggered, a single signal appears at its output, which triggers the actuator 15. At the same time, the gate inputs of the comparators 9 and 10 receive a signal from the output of the comparator 8 through the inverter 11, which prohibits the operation of the comparators 9 and 10.

When one of the phases of attachment is broken, the phase voltages relative to the earth change, the voltage of the damaged phase increases, and the intact phase decreases. The source neutral voltage also increases. The zero sequence voltage Up varies from. 0 ,, with a break at the beginning of the line to its value equal to 0.0426U (p, due to unequal values of phase capacitances. With four lines of six, departing from the distribution device tires, the zero sequence voltage U varies from (0,2-0,3) Ucpn with a break at the beginning of the line to 0,0426 and | with natural asymmetry. Therefore, the threshold of operation of the comparator 9 is set

O.IfIn the closure of one of the phases to earth, the voltage of the damaged phase decreases, and the intact voltage increases. The zero sequence voltage, depending on the completeness of the earth fault, increases to Kf. The threshold for triggering comparator 10 is 0.411.

When the attachment phase is broken, a comparator 9 is triggered, having a trigger threshold lower than the comparator 10. Comparator 8 does not work, because

0

five

In this mode, identical signals are applied to its inputs at a time. Pa inputs of the logical element And 13 receives signals - a logical one and zero, at its output - a logical zero. Signals are sent to the inputs of the logic element I 12 — two logical units, and a logical one to its output. The executive body 16 is triggered for the interruption of the npiico-connection phase.

When the phase of connection to the ground closes, the comparators 9 C- and 10 work, the logic element I 13, is used.

Tensional organ 1 / on short circuit on the earth. Comparator 8, as in the previous case, does not work.

By introducing new elements and new interrelations between elements, the device makes it possible to increase the reliability of controlling the incomplete phase modes of the electrical network.

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Claims (1)

Invention Formula A device for controlling the incomplete-phase modes of the electrical network, containing mode control sensors installed on both sides of the object to be protected, the mode control sensor on the supply side made in the form of a zero-sequence voltage filter first, second threshold organs, first and second inverters, the first logical element And, the first, second, third executive bodies, the output of the sensor control modes, installed by the consumer, is connected to the first input of the first threshold organ, in The output of the mode control sensor, installed on the supply side, is connected to the input of the second threshold organ, characterized in that, in order to improve the reliability of determining the location of damage in networks with high capacitive conductivity, the third threshold organ, the second logic element AND, is additionally introduced the threshold organs are made in the form of comparators, and the mode control sensor, installed on the consumer side, is made in the form of a zero-sequence voltage filter, with the output of the mode control sensor with Toronov-power is connected to the second entrance of the first threshold organ and the entrance of the third threshold organ. 51361669. the output of the first threshold organ of the sub threshold organ is connected to the input of keys to the input of the first inverter and to the second inverter and to the second input of the first executive body, second logic element I, the output of the first inverter is connected to, the stroke of the second inverter is connected to the gating the inputs of the second and third inputs of the first logical element of the threshold organs, the output of the second AND, the outputs of each logical th threshold organ are connected to the element AND are connected to the corresponding - the first inputs of the first and second log the second and third executive elements are And, the output of the third Q is the organs.