SU408224A1 - DC CURRENT TRANSFORMER - Google Patents

Description

Famous DC transformers containing four cores with one common primary and four separate secondary windings connected in series and counter, two supply transformers, two intermediate current transformers, the secondary circuits of which are closed each to its rectifying bridge and the total active load device protection and automation, characterized by the presence at their output of false current surges that occur during sections of the primary current, which negatively affects the operation of devices Protection and automation, causing their false positives.

The proposed device, with the aim of eliminating spurious current surges arising on sections of its primary current at the output of a direct current transformer, is equipped with two additional rectifying bridges, two current transformers, an AND logic circuit, two active resistors and an electronic key, connected in such a way that the primary windings of the mentioned current transformers are included in the secondary circuit of the corresponding pair of cores of the main DC transformer directly or through intermediate transistors Shaper current and the secondary winding via its additional rectifier bridge closed for each resistance to which is connected one of the inputs of the circuit "And, the output of the latter is connected to a control input of the electronic key included parallel to the common active load transformer.

The drawing shows a diagram of the proposed device.

The following designations are accepted: cores 1-4 with secondary windings of a DC transformer 5; rectifying bridges 6, 7 of the load circuit; resistor 8 in the load circuit; device 9, 10 protection and automation. The secondary circuit of each pair of cores includes intermediate current transformers 11, 12, the secondary windings of which, respectively, via rectifying bridges 13 and 14 and resistors 15 and 16 are connected to the inputs of the logic circuit "And 17, which is connected to the control input of the electronic switch 18, turned on at the inputs of devices 9 and 10 of protection and automation, connected by these inputs to a resistor 8. In addition, the diagram shows the supply transformers 19, 20 and intermediate current transformers 21, 22.

The scheme works as follows.

During normal operation of the transformer, the same signal is simultaneously received at both inputs of the circuit 17 with a resistor 15 and 16. At the same time, the output signal of the circuit 17 is absent, the key 18 is closed, and the signal from the resistor 8 freely passes to the devices 9 and 10, which are thus prepared for operation and react to any changes in the current in the load circuit of the transformer 5.

If the primary current is disconnected, then the inputs to the circuit 17, signals from resistors 15 and 16, either do not come at all, or the signal comes only to one of the inputs of this circuit. At the same time, the output of the circuit 17 is a pulse opening key 18. The latter will result in bypassing the signal from the resistor 8 to the inputs of the device 9 and 10 protection and automation, which in this case do not respond to changes in the current in the load circuit of the transformer 5.

If the primary current of the direct current transformer 5 contains a variable component, the amplitude of which is close to the primary current value, then a surge in the current of each pair of cores may occur due to the same reasons as the considered consideration. In this case, the current in the secondary circuits of the cores may not fall to zero. For reliable operation of the device in cases when a surge in current occurs in the secondary currents of transformer 5 in the presence of primary current, the circuit 17 has a reference voltage of approximately 0.1 nominal voltage across resistors 15 and 16.

For reliable operation of the device in static and normal transient modes, when in the secondary currents of each pair of cores there are dips corresponding to the switching times of the secondary currents, memory elements with a storage time of not more than 0.5 ms are included at the inputs of the circuit 17.

Subject invention

A DC transformer containing four cores with one common primary and four separate secondary windings connected in pairs and in series and opposite, two supply transformers, two intermediate current transformers, whose secondary circuits are closed each to its rectifying bridge and to a common resistive load, protection and automation devices, characterized in that, in order to eliminate at the output of the transformer of the direct current, the spurious current surges that occur during slices of its primary current, Two additional rectifier bridges, two current transformers, an AND logic, two resistances and an electronic switch connected in such a way that the primary windings of the above current transformers are connected to the secondary circuit of the respective pair of cores of the main DC transformer directly or through intermediate current transformers, and secondary windings through their additional rectifying bridge are closed each for active resistance, to which the input of circuits is connected "And, the output of the latter is connected to a control input of the electronic key included parallel to the common active load transformer.