SU1707687A2 - Device to protect transformer with secondary winding connected in parallel - Google Patents

Abstract

The invention relates to electrical engineering, namely, relay protection devices, and can be used to protect against short circuits and an open circuit in a secondary winding of a transformer with several parallel connected secondary windings. The aim of the invention is to improve the reliability of the protection operation. The goal is achieved by the addition of a switch, a divider block and an indicator to the transformer protection device. 2 Il.

Description

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The invention relates to the field of relay protection, in particular for protection against short circuits and an open circuit of a secondary winding of a transformer with several parallel secondary windings, and is an improvement of the device according to the author. hi 1492413.

A device for protection of a transformer with parallel connected secondary windings is known, comprising signal generating units proportional to the currents of the secondary windings, signal generating units proportional to the difference between the current of each secondary winding and the average value of their currents, a max selector, a mini selector, an adder and two different polarity reactors body, providing high sensitivity and selectivity at short circuits and break of the secondary circuit of the transformer and the possibility of honoring the decree these modes.

However, with a large number of secondary parallel-connected windings of the transformer, false protection may be triggered due to an open circuit or damage to the elements in the signal generation units proportional to the currents of parallel-connected windings.

The purpose of the invention is to improve the reliability of the device is achieved by the fact that the device for protection of the transformer with parallel connected secondary windings, contains blocks for generating signals proportional to the currents of the secondary windings, blocks for generating signals proportional to the difference between the current of each secondary winding and the average value of currents, inputs which are connected to the outputs of the aforementioned signal conditioning units proportional to the currents of the secondary windings, and the outputs to the combined inputs of a max detector a and a mini selector, an adder whose inputs

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The output is connected to the outputs of the maxi and mini selector, and its output is connected to the combined inputs of two reacting bodies made of different polarities, an indicator, a divider unit and a switch are added, and the intermediate outputs of one half of the signal conditioning units proportional to the currents of the secondary windings are connected through the first group of contacts of the switch with the inputs of the divider unit, and the intermediate outputs of the second half of the blocks are connected via the second group of contacts of the switch with the outputs of the divider block, and through The third group of switch contacts is connected to the outputs of the signal conditioning units proportional to the currents of the secondary windings.

The essence of the invention is to diagnose the circuits of the signal generating units proportional to the currents of the secondary windings of the transformer.

Figure 1 shows the functional diagram of the device: Fig, 2 - one of the possible variants of the protection device acting on the signal when the secondary circuit of the transformer breaks.

The device contains blocks 1. signals at the output of which are proportional to the corresponding currents of the secondary parallel-connected transformer windings, blocks 2. forming signals proportional to the difference between the current of each winding and the average value of their currents, max selector 3. mini selector 4, adder 5, different polarity reacting organs b and 7. switch 8, connecting the indicator 10 to the output of any block 1 and closing the control circuit between blocks 1 through a divider 9.

Diagnostics is carried out when the response of the reacting body 7, which operates when the circuit of one of the secondary windings is open. For this, the switch 8, the indicator 10 is connected to the block 1, the output signal of which is equal to zero. Using the switch 8 and the divider 9, two diagnostic circuits are created in succession, corresponding to the two tests and allowing to determine the health of the signal and the type of fault of the unit 1 by the nature of the signal change on the indicator.

The inputs of the divider 9 resistors (FIG. 2) can be connected to the rectifier input VS TAV1 and TAV2 using the first contact group of the switch SC1.1-SC1,4, and the outputs of the divider resistors using the second contact group of the SC2.1-SC2 switch. 2 can be connected to the input of the rectifier VS remaining block

TAV3. The resistance of the divider resistors is approximately equal to the load of the rectifying bridges; it is much greater than the resistance of the secondary winding TAV.

A voltmeter V, which is an indicator 10, with the help of a third group of contacts SC3.1-SC3.4 of the switch allows you to monitor the voltage at the output of any unit 1.

0 Diagnostics is carried out after the response of the reacting body acting on the signal. In this case, the voltage at the output of one of the blocks 1 becomes equal to zero due to the break of the secondary circuit of the transformer or due to the break of the communication line between the current sensor and the rectifier or breakdown of the rectifier or filter capacitor. Using the contacts SC3.1-SC3.4, the voltmeter V is connected to

0 to the output of this block 1. The realization of the first test of control is carried out by closing two contacts, which create a circuit between the diagnosed block and the block, the voltage of which is used for diagnostics.

5 So. when testing a block with TAV1, either SC1.1 and SC2.1, or SC1.2 and SC2.2 are closed. If a rectifier arm or capacitor is punctured, the voltage on R1, monitored by a voltmeter, will remain equal to zero, otherwise, the output of unit 1 is Vits voltage due to the flow of half-wave current through R1.

The second test of control is carried out by closing two more contacts that apply voltage through the divider 9 to the diagnosed unit. Thus, when the contacts SC1.1 and 5C2.1 are closed, they close 5C1.2 and 5C2.2. If the circuit from the current sensor to the rectifier is 0, then the voltage on R1 decreases, otherwise the voltage on R1 will increase.

The use of a switch, divider and indicator allows you to eliminate false

5 disconnecting the transformer. This leads to an increase in service life and, consequently, to an improvement in its economic performance.

Claims (1)

Invention Formula 0 Device for protection of a transformer with parallel connected secondary windings according to auth.St. No. 1492413, characterized in that, in order to increase the reliability of the device in operation, an indicator, a divider unit and a switch are additionally introduced, while the intermediate outputs of the first half of the signal conditioning units proportional to the currents of the secondary windings are connected through the first contact group of the switch to the inputs of the unit dividers, intermediate outputs of the second half of these blocks are connected through the second group of contacts of the switch with the outputs of the divider block, and Jnv смcm about 1 I -------- 1-t-J-j - I / 4 ----- tssrrb a Y in l kV -. - - at. .- - - - SC7.2 ls; l sc2 .; TM1 -A -Sh L2 I -YU t ii i72 N L the indicator through the third group of contacts of the switch is connected to the outputs of the signal conditioning blocks proportional to the currents of the secondary windings. FAME. H Signal Fig about 1 SC34 1-t-j-j - I / t ii i72 N L FIG. 2