SU1487120A1 - Device for contactless control of single-phase transformer - Google Patents

Description

The invention relates to electrical engineering, in particular to relay protection. purpose

inventions - enhanced functionality by protecting the transformer from damage when one of the thyristors fails. If the primary winding of the transformer 1 receives a half-wave rectified voltage, the capacitor 10 is charged, preventing the flow of direct current through the primary winding of the transformer, saturation and damage to the latter. Depending on the polarity of the voltage on the capacitor 10, one of the lamps 13, 15 goes out, which indicates a failure of thyristor 2 or 3. The joint switching off of the signal lamps 13 (15) and 17 indicates a failure of one of the thyristors 2 or 3 and an alarm condition ovens. 1 h. apt. 1 il.

$ and „„ 148712

1487120

3

The invention relates to electrical engineering and can be used to control and protect the supply of single-phase transformers in electrical installations, such as furnace.

The aim of the invention is to enhance the functionality by protecting the transformer from damage when one of the thyristors fails.

The drawing shows a schematic diagram of the proposed device.

The contactless control device of a single-phase transformer 1 contains two anti-parallel thyristors 2 and 3, the first connection point of which has a terminal for connecting to the mains phase, supplying transformer 1. Between the control terminals of the thyristors 2 and 3 a circuit is connected from the series connected first closing contact 4 of the relay 5 controls and resistors 6 and 7. In parallel, thyristors 2 and 3 include a KS circuit from resistor 8 and capacitor 9. The second connection point of the thyristors is connected to the first lead of the capacitor 10, the second oh pin which has a clip for connection to the first output of the primary winding of the transformer 1. To the junction point of the capacitor 10 and thyristors 2 and 3 through the second closing contact 11 of relay 5 are connected two parallel circuits consisting respectively of the first diode 12 and the signal lamp 13 and the second diode 14 and the signal lamp 15. In this case, the diodes 12 and 14 are included in opposite one with respect to the other. The point of connection of the lamps 13 and 15 has a clip for connection to the second output of the primary winding of the transformer 1.

The circuit of the series-connected third closing contact 16 of the relay 5 and the signal lamp 17 has clamps for connection to the secondary winding of the transformer 1 connected to the load 18, for example, a furnace.

The device works as follows.

In normal mode, all signal lamps 13, 15, 17 are lit, signaling the normal operation of the thyristors (lamps 13, 15) and the furnace (lamp 17).

When one of the thyristors 2 or 3 fails, the half-wave rectified voltage is applied to the primary winding of the trans _{7 of the} formator 1. The capacitor 10 is charged to the amplitude value of the supply voltage (of corresponding polarity), preventing the flow of direct current through the primary winding of the transformer 1, saturation and. damage to the latter.

four

Depending on the polarity of the voltage on the capacitor 10, one of the lamps 13 or 15 goes out, signaling the failure of the thyristor 2 or 3. The absence of current in the primary and secondary windings of the transformer causes the lamp 17 to go out.

The joint extinction of the lamps 13 (15) and 17 indicates the failure of the thyristor 2 (3) and the emergency state of the load (furnace).

Thus, the introduction of a capacitor and display circuits prevents damage to the transformer when one of the thyristors fails and the device is monitored for operability.

Claims (2)

Claim 1. A contactless device that controls a single-phase transformer containing two anti-parallel thyristors, the first connection point of which has a clip for connecting to the phase of the power supply network, a COP circuit connected between the first and second connection points of the thyristors, and a chain of series-connected variable resistor and the first closing contact of the control relay connected between the control terminals of the thyristors, characterized in that, in order to extend the functionality by implementing protection transformer from damage when one of the thyristors fails, an additional capacitor is added to it, the first terminal of which is connected to the second thyristor connection point, and the second terminal has a clip for connection to the first terminal of the transformer primary winding. 2. Device by π. 1, characterized in that, in order to monitor the operability of the device, three signal lamps are additionally introduced in it, two diodes and the second and third closing contacts of the control relay, while the first terminals of the first and second signal lamps are combined and have a clip for connecting to the second the output of the primary winding of the transformer, the second outputs are connected respectively to the cathode of the first and the anode of the second diode, the anode and cathode of which are combined and through the second closing contact of the control relay are connected to the first output to capacitor, a chain of series-connected third signal lamp and a closing contact of the control relay has clamps for connection to the terminals of the secondary winding of the transformer.