SU1179473A1 - Device for protection of autotransformer against incomplete phase operation - Google Patents

Abstract

A DEVICE FOR PROTECTION OF THE TRANSFERER FROM A FULL-PHASE OPERATION MODE, containing current transformers of zero sequence, high and medium voltage sides, to the secondary windings of which current relays are connected, and their short-circuiting contacts are connected in parallel with each other and in series with the winding, time relay, short-circuit contact which is included in the circuit of the executive body, voltage transformers of zero sequence of the sides of high and medium voltage, power direction relay, current winding The ogo is connected to the parallel windings of the secondary transformers of the zero sequence of the medium voltage side and neutral side, the closing contact of the relay, the power direction is connected in series with the contacts of the current relay, i characterized in that, in order to increase the sensitivity (L and simplify, the secondary windings of transformers The terminals are connected in series and connected to the voltage winding of the power direction relay. "H with

Description

The invention relates to electrical engineering, namely, to relay protection of elements of energy systems, and can be used to protect autotransformers and transformers.

The purpose of the invention is to increase the sensitivity and simplify the device.

The drawing shows a diagram of a device for protecting an autotransformer from an incomplete phase operation.

The incomplete-phase operation mode is installed on the autotransformer 1 connected to the network through switches 2 and 3 connected to buses, on which voltage transformers 4 and 5 of the zero-sequence side of the middle and high voltage side are installed, current transformers 6, 7 and 8 of the zero-sequence, respectively medium voltage, higher voltage and neutral, current relay 9 and 10, power direction relay 11, its closing contact 12, which closes when the input values do not match. The closing contacts 13 and 14 of the current relay 9 and 10 respectively are a time relay, the winding 15 of which is connected in series with the closing contacts 13 and 14 of the current relay, and its closing contact 16 is included in the circuit of the executive body.,

The voltage Up and the current 1p applied to the relay are formed according to the expressions m:. .

.-Uv

,

where Uc, Ug is the zero-sequence voltage of the sides of the middle and higher stresses;

1. and 1 „- the zero current of the middle side and the neutral current, while the current supplied to the relay is shifted by 90.. Thus, with external asymmetry, the current and voltage applied to the relay are in antiphase, and the longitudinal internal asymmetry

in phase. The operating current of the current relays 9 and 10 is selected from the condition of the detuning from the unbalance voltage.

Protection works as follows

In the absence of an unbalance source, current relays 9 and 10, power relay 11 are in an inoperative state, and their contacts 12, 13, and 14 are open, winding 15 of the time relay is de-energized, and its contact 16 is open.

When internal longitudinal asymmetry, for example, if the phase switch 2 or 3 fails to turn on, the voltage on the medium and higher voltage buses is opposite in phase and, consequently, the power relay operates and closes its contact 12 and when the current relay 9 or 10 is triggered, a circuit appears through the winding The 15 time relays and through a power delay of the time relay, built up from the time of the phase difference of the on / off switch, closes the contact 16 of the time relay and disconnects the autotransformer 1 from rati.

With external asymmetry, the zero-sequence voltage on medium and high voltage tires coincide in phase, which leads to non-failure of the power relay 11 and its contact 12 will be open. Thus, the circuit of the winding 15 of the time relay I is not open and the relay does not operate.

The use of a power direction relay, to which the sum of the zero-sequence currents of the middle side and the neutral current, as well as voltages equal to the difference between the zero-sequence voltages of the middle and high sides, allows detecting the modes of external and internal longitudinal asymmetry, increase the sensitivity of the protection device, since there is no need: to rebuild the protection with a / t external asymmetry, as well as to simplify the protection device that does not require a bi-directional power direction relay intermediate relays.

Claims (1)

DEVICE FOR PROTECTING THE AUTOMATIC TRANSFORMER AGAINST INPHASE OPERATION MODE, containing zero-sequence current transformers of the sides of high and medium voltage, to the secondary windings of which are connected current relays, and their make contacts are connected in parallel with each other and in series with the winding, with a time relay, make contact which is included in the circuit of the executive body, voltage transformers of zero sequence of the sides of the high and medium voltage, power direction relay, the current winding of which connected to parallel secondary windings of the zero-sequence current transformers of the medium-voltage side and neutral side, the make contact of the power direction switch is connected in series with the contacts of the current relay, characterized in that, in order to increase sensitivity and simplification, the secondary windings of voltage transformers are connected in series and connected to the voltage winding of the power direction switch. SU ..... 1179473>