SU902132A1 - Relay protection system and device for testing it under load - Google Patents

Description

one

The invention relates to electrical engineering, in particular, to devices for testing a relay sander, and for power stations and substations during operation of the protection of my connection under load.

A device for checking the relay protection under load is known, which contains a source of control current and a current transformer with two secondary windings, one of which is connected to a relay unit, and the other, together with a source of control current, is connected counter-parallel to the first rev. hank 1.

The drawbacks of this device are associated with the use of an external power source when checking.

The closest to the proposed technical entity is a device for relay protection with checking its current elements under load, containing the main current transformers, to the secondary windings of which a relay unit and an additional current transformer are connected, the secondary winding of which is connected to each of the tested relays of block 2.

The known device allows testing the relay block with the load current of the main current transformers, however, the size and phase of the control current can be controlled using only 5 steps, which are caused by a discrete change in the transformation ratio of the additional current transformer. The magnitude of these stages, and hence the accuracy of the test, is determined by the magnitude of the operating load current and the number of branches of the additional current transformer. The latter is limited by the number of turns of its secondary winding. In addition, the device does not provide verification of multiphase relays, in particular, three-phase current relays 15 of direct sequence, current relays with negative-sequence filters, etc.

The purpose of the invention is to increase the accuracy of checking the operating setpoint and to ensure the possibility of checking multiphase relays.

The goal is achieved by the fact that in the device containing the main current transformers, the secondary windings of which are connected to a relay unit and an additional current transformer, the primary winding of which is connected to the main current transformers, and the secondary winding is connected to each of the tested unit relays, an additional current transformer is made with three primary windings, which are included in each of the phases of the main current transformers sequentially and shunted each and the adjustable resistor.

In addition, in the device, the number of additional current transformers and selection keys of the element under test corresponds to the number of phases used in multiphase relays.

FIG. 1 shows a diagram of a device for testing relay protection under load; in fig. 2 - vector diagram of currents when checking a current relay with a reverse sequence filter.

The device contains the main current transformers to the secondary windings of which a testable current relay with a reverse-sequence filter 4 is connected, containing current transformers 5 and 6 with primary windings 7-10 and additional current transformers 11 and 12 with primary 13-18 and secondary 19 and 20 windings which are connected to each of the phase windings 7 and 9 of the checked relay 4 through the switches 21 and 22 of the choice of the element under test. All the windings of the additional transformers 11 and 12 of the current 1 are connected by adjustable resistors 23-30, and their second windings 19 and 20 included measuring devices 31 and 32. Protective earth 33 is included in the neutral wire of the main transformers 1 -3 current.

When the protected connection is operating under load, all adjustable resistors 23-30 are inserted and a symmetrical three-phase current flows through the phase windings 7 and 9 of the current relay 4 and the windings 13-18 of the additional current transformers 1 and 12. In this case, due to the equality of the number of turns of the windings 13-18, the total magnetic flux of the additional current transformers 11 and 12 is insignificant and an unbalance current flows in the secondary windings 19 and 20. When checking the current of the direct sequence of windings 7 and 9, a reverse sequence current of additional current transformers 11 and 12 is superimposed. To this end, their secondary windings 19 and 20 are connected by keys 21 and 22 of the selection of the element under test to phase windings 7 and 9, respectively. Resistance Removal

adjustable resistors 24 and 26 smoothly increase the suction currents km (Fig. 2a, and b), as a result of which the currents in the primary windings 1pi P16 decrease, and the currents in the secondary windings IBT vta increase in accordance with the accepted coefficient

transformations of additional transformers 11 and 12 current. The latter are superimposed on the forward sequence current d. If, a relay 4 with a phase corresponding to the negative sequence current 1ag

 There are two (c) which are selected by the filter of relay 4 and act on its measuring organ. This component is counted by measuring instruments 31 and 32.

The device allows when checking under

load without the use of an unauthorized power source to improve the accuracy of checking the working setpoint and to ensure the possibility of testing multiphase current relays. The technical and economic efficiency of the device is due to the possibility of performing preventive checks without shutting down the protected connection,

Claims (2)

Invention Formula 5 1- Device for relay protection and testing it under load, containing the main current transformers, the secondary windings of which are connected to a relay unit and an additional current transformer, the primary winding of which is connected to the main current transformers, and the secondary winding through the switch of the element to be tested Connected to each of the relays of the block, characterized in that, in order to increase the accuracy of checking the working set, an additional current transformer is made with three primary windings, which are included in each of the The main current transformers are sequentially and bridged each with adjustable resistors. 0 2. The device according to claim 1, characterized in that, in order to enable and test multiphase relays, the number of additional current transformers and selection keys of the element under test corresponds to the number of phases used in multiphase relays. Sources of information taken into account in the examination 1. Japanese patent number 49-7929, cl. H 02 H 3/02, 1973. 0 2. USSR author's certificate for application number 2725542 / 24-07, cl. H 02 H 3/08. H 01 H 69/01, 1979.