SU752605A1 - Apparatus for protecting electric installations - Google Patents

Description

A diode block is turned on, and horn-type arresters are installed on the fuses of the secondary circuits, one electrode connected to the fuse insert and the other to the internal grounding circuit.

In addition, to increase the speed of protection and its redundancy in series with the diode unit, a current transformer is additionally connected, the secondary winding of which is connected to the control electrode and the cathode of the newly introduced thyristor connected between the positive pole of the operational DC source and the actuators.

FIG. 1 and 2 is a schematic diagram of the device; in fig. 3 - fuse with horn discharge.

The device contains an operational DC source 1 for the secondary circuits 2 of the electrical installation, an internal 3 and an external 4 grounding circuits and installed in the connections of connection 5 between the grounding circuits of the current relay 6. Between the negative pole of the operational DC source 1 and the internal grounding circuit 3, a diode unit 7 is connected. The current relay 6 is connected to the executive bodies 8. On the fuses 9 in the secondary circuits of the electrical installation, horn arresters 10 are installed, one electrode connected to terminal 11 fuse, and the other with an internal grounding circuit 3.

Conventional fuses (Fig. 3) with a fusible insert can be fitted with horn dischargers. To do this, on one side of the fuse a hole is drilled and one electrode of a 12-horn-discharge cell is fixed on the terminal to which the secondary circuit is connected. The other electrode 13 of the corneal discharge, located at a short distance from the first one, is connected to the internal grounding circuit 3. The horn dischargers on the fuses are installed on the side entering the secondary voltage circuit of 3.3 kV from the power current source 14.

In another embodiment of the device (Fig. 2), a transformer 15 is connected in series with the diode unit 7, the secondary winding of which is connected to the control electrode and the cathode of the thyristor 16. The latter is connected between the positive pole of the operational DC source 1 and through the diodes 17 with actuators 8 .

The device in the first embodiment works as follows.

When a current, for example, a voltage of 3.3 kV from a power source of current 14 enters the secondary circuit 2, it passes through an operational DC source 1, a diode unit

7, the internal grounding circuit 3, the current relay 6 passes to the external grounding circuit 4. The current relay 6 operates and gives a signal to the executive body 8, which act on the high-speed switch 18 and disconnect the electrical installation from the power source 14. In addition, the executive bodies 8 disable electrical installation corresponding

switches from make-up from the external network.

Thus, the diode unit 7 equalizes the potentials of the cores of the secondary circuit 2 and the internal grounding circuit 3 at

high voltage in the secondary circuits and, forming a circuit for a short circuit current, creates the conditions for disconnecting the power source 14 for the forward current.

With an increase in current in the secondary circuits, the fuses 9 are burned, and the ionized plasma is pulled out of the fuse through the hole at high speed, making the air gap between the electrodes

Horn level 10 conductive. An arc and a current arise between these electrodes, the secondary circuits after fuse 9, goes to the internal ground 3, and through the current relay 6 to

external ground loop 4. The damage is localized and has a very small size.

The device according to the second variant has a higher case and speed and works as follows. When a short circuit current passes through a transformer 15, the voltage induced in the secondary winding is applied to the control electrode of the thyristor 16, which opens and passes current directly to the actuating devices 8. Further shutdown of the electrical installation occurs in the same way as in the first variant. Speed is achieved in

by eliminating the response time of the current relay 6 and their followers (not shown in the drawing).

The reliability of this device is higher, because it works even in the case of

shunting the current relay between ground circuits when the current relay does not operate.

Claims (2)

1. Device for protection of electrical installations, containing an operational DC source for secondary circuits, fuses, internal and external grounding circuits and connected in cutting between said current relay circuits, associated with actuators, in order to increase device reliability and speed, between the negative pole of the operational source of direct current and the internal grounding circuit is additionally included a diode unit, and on the fuses of secondary prices tanovleny surge arrestor horn, one electrode connected to the fuse link, and the other - with the inner earthing circuit. 2. The device according to claim 1, characterized in that, in order to increase the speed of protection and ensure its redundancy, a current transformer is additionally connected with the diode unit, the secondary winding of which is connected to the control electrode and the cathode of the newly introduced thyristor connected between the positive pole operational source of direct current and executive bodies. Sources of information taken into account in the examination 1. Gruber L. O. and others. Electric power stations and traction substations, M., “Energii, p. 314-316, fig. 9-5, 9-6. 2. USSR author's certificate number 264516, cl. H 02 H 7/22, 1970.