SU1325616A1 - Device for differential protection of busbars - Google Patents

Abstract

The invention relates to electrical engineering. The purpose of the invention is to increase the speed. This is achieved by separating the first harmonic indirectly as the difference between: the total differential current and the generator corresponding to the higher harmonics. In the absence of the first harmonic filter, the response time is determined only by the release time of the higher harmonics by filter 3 and the response time of the code body .8. 1 il.

Description

1 13

The invention relates to electrical engineering, namely, relay protection, and can be used as a differential current protection for busbars of power stations and substations.

The purpose of the invention is to increase speed,

The drawing shows the scheme of the proposed device for differential tire 3audits.

The device contains current transformers 1 connected in a differential circuit, a nonlinear element 2 connected in series, a high harmonic filter 3, an intermediate transformer 4 loaded on active resistance 5, rectifiers 6 and 7 on opposite side, output element .8,

The device works as follows,

In case of external damage, the differential current is not sinusoidal, since it is the magnetizing current of the transformer of the damaged connection ,, In this case, the high relative harmonic content and, therefore, the high voltage at the output of the filter 3, and the highest the components are emphasized due to the presence of a nonlinear element 2, since in this case the unbalance current flows under the action of a voltage source with an internal resistance equal to the resistance of the shoulder damaged connection, the output body 8 of the device does not work.

In case of internal damage, the differential current is less distorted, and in addition, it proceeds under the action of an equivalent current source, therefore, it is almost not distorted under the action of nonlinear element 2, therefore, with the internal compounter A. Bondarenko L.Oliynyk Proofreader S.Shekmar

Order 3119/51 Circulation 617 Subscription

VYIIPI USSR State Committee

on invention and discovery Ii3035s Moscow, Zh-35, Raushsk nab, d, 4/5

Production and printing company, Uzhgorod, st. Project, 4

16, 2.

the damage of the voltage of the first harmonic is greater than that of higher harmonics, and the device reliably works.

In the proposed device, the first harmonic is obtained indirectly as the difference between, a full signal proportional to the differential current and a component corresponding to higher harmonics.

Since in the proposed device the time of the first harmonic separation is the same as the higher 1 armonic components, the time of its operation is practically determined by the time of work of the output organ 8,

Claims (1)

Invention Formula A device for differential busbar protection, containing a current transformer, the secondary windings of which are connected in a differential circuit and connected to series-connected high-harmonic filters and a nonlinear element, two watches, the outputs of which are included counter and sub-. They are connected to the output organ, the input of the first rectifier is connected in parallel to the filter of higher harmonics, which is so that, in order to improve speed, an intermediate current transformer and resistance connected parallel to the secondary winding of the intermediate current transformer are additionally introduced which is connected in series with a harmonic filter and a non-linear element directly to the secondary windings of the current transformer, the second rectifier is connected in parallel chain consisting of filter higher harmonics and intermediate secondary winding of the current transformer,