SU1647756A1 - Device blocking relay protection operation for supply circuit faults - Google Patents

Abstract

This invention relates to electrical engineering, in particular, to relay protection devices. The purpose of the invention is to increase reliability by detuning from unbalance currents. The device blocks and signals the failure of two blocks of relay protection when current circuits malfunction on any of them due to imbalance of magnetic fluxes from the difference of phase currents and zero star circuit after switching on current protections in the middle rod of a three-core magnetic circuit. Extreme rods of the last form magnetic fluxes and cause braking currents of the comparison circuit of two electrical quantities in absolute value. providing the required braking characteristics of the blocking relay of each protection. 2 Il.

Description

The invention relates to electrical engineering, in particular, to relay protection devices, the failure of the current circuits of which can cause their false action.

The purpose of the invention is to increase reliability by detuning from unbalance currents.

FIG. 1 shows the scheme of the proposed device; in fig. 2 is a device response characteristic.

The device for blocking relay protection in case of malfunction of the power supply circuits contains a measuring three-pole current transformer 1, x secondary windings 2 and 3 of the first extreme and middle rods are connected via rectifying bridges 4 and 5 of the blocking relay of the first relay protection unit 7 power through the opening contact 8 of the relay 6 blocking, the closing contact 9 of which is included in the alarm circuit. The second block of relay protection is connected to the secondary windings 10 and 11 of the middle and second extreme rods

current transformer 1 is similar to the first block of 7 relay protection.

The device works as follows.

With any changes in the currents in the primary circuit of transformers toké for protection against phase C1 and C2 and zero 01 and 02 wires of their power supply, magnetic fluxes in the magnetic conductor of transformer 1, the current causes EMF on the secondary windings depending on their location: on the outermost rod winding 2 is proportional to the current, and on the middle dwelling core 3 is proportional to the difference of the currents.

The blocking relay 6 is configured according to the characteristic (Fig. 2), where the parameters of the braking current 1T are determined by the emf of coil 2 and the operating current 1p from coil 3. By activating the locking relay 6 via rectifiers J and 5 from coils 2 and 3 according to the scheme of comparing two electrical quantities in absolute value, the tripping current 1Ср has a dependent characteristic of operation /

WITH

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IPIII from brake gok, which provides the rack against possible current unbalanced 1ts (with different loading of measuring transformers and large multiples of primary current during a short circuit (hz) in the network. The selected braking characteristic of blocking relay 6 eliminates the possibility of false blocking of protection for any kind of short circuit in the network and the health of the current circuit power supply protection.

If any phase wire is broken, due to the absence of compensation of the magnetic flux in the middle core of the current transformer 1 magnetic core, its current becomes proportional to the phase or two phase current if the treated phase C is broken. When two untreated phases break, the magnetic flux is also proportional to the phase current, two phases treated - the difference of currents of the remaining phase and processed. At break of three phases the magnetic flux is also proportional to the current of the phase.

When an interruption in any combination of phases or when they are shunted to the point of control in the supply power circuits, a magnetic current is generated in the secondary core of the current transformer 1 on the secondary winding 3 and the voltage triggers the blocking relay and prohibits the first relay block 7 from opening. contact 8 and fault signaling closing contact 9.

The inclusion of the primary windings C1 and 01 from one set of current transformers with the same polarity of the same wires C2 and 02 of another set of the same current transformers provides the response of the blocking relay 6 to an interruption of the current of each set. The second set of current transformers has a similar blocking scheme of the protection unit connected to it against the same secondary windings 10 and 11 with the same principle of operation.

If the neutral wire is broken, the action of the relay protection unit against the flow through the primary circuit of the zero sequence currents is ensured until the alarm is triggered to eliminate this defect, which can cause overvoltages and bridging of the circuits with a complex action of the relay protection unit if they are not blocked.

Implementing the specified lock is not

represents the three types of THI.iark; and the high-performance version of the current transformer gpdpzhit no less than two secondary windings whose current circuits are provided

a common blocking device, the setting of which is lower than the current of operation of the blocking protection and higher the characteristic of the possible unbalance current due to errors in the operation of current transformers with a high multiplicity of currents to s.

With a larger number of secondary windings and the need to monitor their serviceability it is possible to pair the current circuits of different sets of transformers

current for their joint control and blocking of the corresponding protections, which, according to the settings, can be triggered by the load current in case of failure of the current circuits of both filter and differential protections. Similar blocking is possible both with a star circuit and a triangle or with current differences when the corresponding analogous phase currents of different sets of current transformers are included.

Claims (1)

Invention Formula Device to lock the relay protection in case of malfunction of the power supply circuits, containing a measuring current transformer with primary windings, designed to be connected to the output circuits of the relay protection, phase and the neutral wires of which are interconnected to the secondary winding of the measuring current transformer are connected to a blocking relay with a normally open contact for connection the operational circuits of the relay protection blocks to the power rails, characterized in that, in order to increase reliability by detuning from the unbalance currents made three-pole, the primary windings are located on the extreme rods of the indicated magnetic circuit with the same winding, the secondary windings of the first extreme and middle rods are connected the blocking relay of the first block of relay protection according to the scheme of comparing two electrical quantities, while the same connection of the second one of the second relay is made from the secondary winding of the second extreme magnetic core of the measuring current transformer.