SU1339730A1 - Apparatus for overload protection of transformer supplied from thyristor regulators - Google Patents

Abstract

The invention relates to electrical engineering and is intended to protect a transformer against overload when it is powered from thyristor controllers. The purpose of the invention is to increase the sensitivity when one of the supply voltage half-waves disappears. This is achieved by the fact that in normal operation, the opposite polarity signals from the secondary windings of the measuring transformer 1 voltage are integrated with the KC circuits and fed to the inputs of the comparison element 8, made in the form of a comparator, the output of which in this mode is zero . When one of the thyristors fails, one of the half-waves of the voltage on the secondary winding of the measuring transformer 1 disappears and the balance of voltages at the inputs of the comparator 8 is disturbed, which leads to its failure. The occurrence of a positive or negative signal at the output of the comparator 8 triggers an electronic relay and the executive body 14, which sends a signal to turn off the power of the protected transformer. 1 il. tg (L with so with so -vj with fi p; j

Description

The invention relates to electrical engineering, in particular, to a relay technology, and can be used to protect transformers 5 powered from the AC mains through two anti-parallel connected thyristors.

The purpose of the invention is to increase the sensitivity of protection in case one of the half-waves of a feeding man disappears.

The drawing shows a schematic diagram of the proposed device.

The device contains an input information sensor 1, made in the form of a voltage measuring transformer, the primary winding terminals of which serve to connect to the primary windings of the protected transformer, the first and second RC circuits from resistors 2 and 3 and capacitors 4 and 5, respectively, first 6 and The second 7 diodes, the anodes of which are connected to the common point of connection of the first outputs of the resistor and capacitor of the corresponding KS circuit, the comparison element 8, made in the form of a comparator, an electronic relay including a transistor 9 p-n-p structure, the third 10 and fourth diodes 11 and first 12 and second 13 resistors.

The collector circuit of transistor 9 includes a winding of the actuator-relay 14, the contact of which is included in the disconnecting circuit of the protected transformer. The beginning, end, and output of the middle point of the secondary winding of the voltage measuring transformer 1 are connected respectively to the anodes of the first 6 and second 7 diodes and the total length. The inverter and non-inverting inputs of the comparator 8 are connected to the second terminals of the resistors 2 and 3, respectively, the first and

the second RC circuit, the second conclusions of the condensate 5 comparison, made in the form of commutators 4 and 5 of which are connected to the observator, makes it possible to increase the sensing bus. The output of comparator 8 is connected to the connection point of the cathode of the third 10 and fourth 11 diodes of the electronic relay, the base and emitter of the transistor of which are connected respectively to the anode of the third 10 and cathode of the fourth 11 diodes and through the first 12 and second 13 resistors respectively to the common bus. about 50

protection to the disappearance of one of the half-waves of the supply voltage due to the introduction of a voltage control, which depends on the non-linearity of the protected transformer less than the current of this transformer.

Claims (1)

Invention Formula A device for protection of the transformer against overload when it is powered from the thyristor controllers, containing the sensor of the input information, with a flame. In the normal mode of operation of the protected transformer (with good thyristors), the positive and negative half-waves of the voltage induced on the secondary winding of the measuring transformer 1 are equal. Therefore, the voltages on the capacitors 4 and 5, the charge of which is realized by the half-waves of different polarity, of the voltage of the secondary winding of the transformer 1, are also equal. In case of equality of signals at the inverting and non-inverting inputs of the comparator 8, the signal at its output is zero. When this transistor 9 of the electronic relay is closed and the current in the winding of the executive body 14 is zero. When one of the thyristors in the power supply circuit and the transformer to be protected breaks, one of the half-voltage on the secondary winding of the measuring transformer 1 disappears. At the same time, the voltage on one of the capacitors 4 or 5 decreases to zero. At the output of the comparator 8 depending on for which input (inverting or non-inverting) there is no voltage, a positive or negative signal appears. The transistor 9 then opens either a negative signal from the comparator output applied to the base of transistor 9 through diode 10, or a positive signal applied to the emitter through diode 11. This causes current to appear in the relay coil 14, when triggered, a signal is given to turn off the protected transformer. Thus, the performance of the sensor input information in the form of a measuring voltage transformer, the various signals from the secondary winding of which are integrated by means of a KS circuit and fed to the inputs of the element comparison, made in the form of a comparator, allows you to increase the sensitivity protection for the disappearance of one of the half-waves of the supply voltage due to the introduction of a voltage control, which depends on the non-linearity of the protected transformer less than the current of this transformer. Invention Formula comparison, made in the form of a comparator, allows you to increase the sensitivity Device for protecting the transformer against overload when it is powered from the thyristor controllers, containing the input information sensor, the comparison element, the first and second KS circuits, to the common connection point of the first terminals of the resistor and capacitor of which the anodes of the first and second diodes are connected, an electronic relay, A pnp structure made on the transistor, to the base and to the emitter of which the anode of the third and fourth cathode diodes are connected, respectively, and the executive body, characterized in that, in order to increase the senses In case of failure of one of the supply voltage half-waves, the input information sensor is made in the form of a voltage measuring transformer, the primary windings of which are used to connect to the primary windings of the protected transformer, the beginning, end and middle point of the secondary windings of the voltage measuring transformer connected, respectively, with the cathodes of the first and second diodes and the common bus; the comparison element is designed as a comparator, the inverting and non-inverting inputs of which are The first and second QC circuits are connected to the second pins, respectively; the second pins of the capacitors are connected to the common length; the comparator output is connected to the cathode connection point of the third and anode of the fourth diode of the electronic relay; the base and emitter of the transistor are connected via the first and second resistors with a common bus, the winding of the actuator-relay is connected to the collector circuit of the said transistor.