SU38221A1 - Device for the protection of electrical installations - Google Patents

Description

The main patent No. 35719 describes a device for protection of electrical installations in which the secondary circuit of a measuring current transformer includes: primary winding of an additional current transformer, winding of a main relay used to close the contacts that shunt under normal load the secondary winding of said additional transformer that turns off the oil sheath And finally, the spark-arresting coil of the auxiliary relay, which serves to open the contacts that shunt under normal load, turn off grease coil oil cooler. To possibly reduce the breaking capacity at the contacts of the main relay and reduce the voltamps of the auxiliary current transformer, the winding of the auxiliary relay is connected to the secondary winding of the auxiliary current transformer and is excited when the contacts of the main relay are opened. The proposed modification of the described device is intended to simultaneously protect against reverse current.

In FIG. 1 shows a diagram of a device for maximum directional protection, and FIG. 2 is a circuit of it, in case of use, for the protection of two parallel LINES.

The primary winding of the additional transformer 6 (Fig. 1) connected, as in the device described in the main patent, in series with the winding of the maximum relay 2 And the arcing coil of the additional relay 9 to the terminals of the measuring current transformer, includes the current winding 10, W of the element the relay / 7 reverse current directions and the winding of the auxiliary maximum 72 relay used to close the polarizing winding circuit 13 of said directional element. In parallel with the secondary winding of the auxiliary transformer 6, the auxiliary winding / - # relay / 7 is turned on, which is used to close the contacts 75 of this relay, which are in the circuit of the shut-off coil of the oil switch. The directional relay has two elements directed and that is enough in installations with low power ( no more than 35 kV) and an isolated neutral for which the proposed device is intended. Maximum relay 2 must be selected with a limited-response characteristic.

The coupling of the phases of the current and voltage in the directional switch can be made according to the Aron circuit. Adjusting the current start of the maximum relay

may be normal (about 140–200% of nominal), the time delay during a short circuit is chosen for reasons of fast protection action in case of damage (about 0.5–1 s or more). The auxiliary relay has a starting current slightly higher than for the maximum relay (on the order of 200% of the nominal).

When a reverse current flows in the return line, the relay / 2 is energized and supplies the voltage to the corresponding windings of the energy direction relay, whereby its contact is made to turn off the oil switch. After a set time delay, the maximum relay 2 is active and opens its contacts, which have previously short-circuited the secondary winding of the additional transformer & Due to this, current is supplied to the winding 14 and the winding controlling the contacts of the relay 9.

Under the action of the winding 14, the circuit of the shut-off coil of the oil switch is closed and the massive coal and copper contacts of the relay 9 are simultaneously opened, as a result of which current is supplied to the switch-off circuit from the current transformer and the lubricator shuts off the line.

in the case of using a device for protection of two parallel transmission lines (Fig. 2), reverse current relay 11 must be equipped with two systems of contacts 15 and 15, included in the circuit of the switching mechanisms of the corresponding oil switches. In this case, in case of external overloads and short circuits, the x currents of the current transformers are balanced in the eight, and the relay does not come into action. In case of a two-pole or three-pole short circuit in one of the lines or the presence of a reverse current, the action of the device is similar to that described above.

If there are several supply or outgoing lines, an even number of them can be associated with the eight-dimensional protection of FIG. 2 (for each pair), and the remaining odd line may have the most directional protection of FIG. 1. Due to this, the number of relays is reduced to a minimum. In addition, both of the above schemes allow switching on measuring devices (with sufficiently powerful current transformers), and also allow a large amount of power to be supplied to the output coils, which, when correctly counted, these coils make it possible to use any type of oil circuit breakers and in many cases x use sleeve current transformers.

The use of energy in relays circuits with an external effect on the contacts makes it possible to realize a high sensitivity of the relay and to minimize the dead zone.

The subject matter of the invention.

Claims (2)

1. The form of execution of the device for protection of electrical installations according to patent No. 35719, characterized in that, in order to apply the device for protection against reverse current, the primary winding of the auxiliary transformer 6 is connected to the current winding element 10 of the relay // element of the reverse current and winding auxiliary maximum relay 12, which serves to close the circuit of the polarizing winding 13 of the directional element, and parallel to the secondary winding of the same additional transformer 6, the auxiliary winding 14 of relay 11 is turned on, It serves to close the contacts 15 of the latter, which are located in the circuit of the oil coil breaking switch (Fig. 1). 2. When using the device according to claim 1 for the purpose of using it to protect two parallel transmission lines, use in the relay 11 a reverse current two systems 15 and 15 contacts included in the circuit of the switching mechanisms of the corresponding oil switches. To see my avtocom I certificate No. I. Kravtsov 38221 FIG. 2 "," one Wed and 1