SU1681362A1 - Device for protection of power two-winding transformer with two-side feed - Google Patents

Description

one

(21) 4041741/63

(22) 02/14/86

(46) 09.30.91. №36

(75) Yu. A. Stepanov

(53) .314 (088.8)

(56) Black-browed N. V. Relein protection. M .: Energie, 1971, p. 512.

(54) DEVICE FOR PROTECTION OF POWER TWO-WATER TRANSFORMER WITH BILATERAL POWER

(57) The invention relates to electrical engineering, in particular to devices for relay protection of power transformers. The purpose of the invention is to increase the sensitivity of protection to winding short-circuits and windings of a power transformer. To achieve this goal, two relays 4 and 5 of the power direction, two capacitors 6 and 7, two double-wrap saturating transformers 8 and 9, two active-capacitive chains 10 and 11 are inserted into the device. Current windings of the relays 4 and 5 of the power direction are connected between the outputs of the transformer 1 of the phase winding of the higher voltage of the power transformer and the inputs of the same phases of the current relays 3, and the voltage windings of the relays 4 and 5 of the power direction are connected through capacitors 6 and 7 and two-winding saturating transformers 8 and 9 between the transformer outputs The armature 2 is the phase winding current of the lower voltage of the power transformer and the inputs of the same phases of the current relay 3. 2 Il.

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Fig 1

The invention relates to electrical engineering, in particular to devices for relay protection of power transformers with double-sided power supply against short circuits.

The aim of the invention is to increase the sensitivity of protection to short-circuits of the windings of a power transformer.

FIG. 1 shows a diagram of the device for protection of a power two-winding transformer with two-way power supply; in fig. 2 is a circuit for turning on the windings of a current relay.

The device contains two transformers 1 and 2 of the current, one of which is connected in delta 4 is installed on the side of the high voltage winding, and the other is connected to an incomplete star and is installed on the side of the low voltage winding of the power transformer, and by the number of phases there are current relays 3, connected to the difference of the phase currents of the current transformers 1 and 2, between the inputs of current relays 3 and the outputs of current transformers 1 and 2 include two relays 4 and 5 of the power direction, two capacitors 6 and 7, two two-winding saturable transformers 8 and 9, and two active Capacitive chains 10 and 11, each of which consists of a capacitor 12 and a resistor 13 connected in series, the current winding of the power direction relay 4 is connected between the current transformer 1 output of one phase of the high voltage winding of the power transformer and the same phase current relay 3 input, and the current winding of the relay 5 of the Power direction is connected between the output of the transformer 1 of the third phase winding of the higher voltage of the power transformer and the input of the same phase of the current relay 3, the winding of the relay of the 5 direction of power The capacitor 6 is connected to the secondary winding of the saturating transformer 8, the primary winding of which is connected between the output of the transformer 2 current of one phase of the low voltage winding of the power transformer and the input of the same phase of the current relay 3, and the voltage of the second relay 4 directing the power through the capacitor 7 connected to the secondary winding of the saturating transformer 9, the primary winding of which is connected between the output of the transformer 2 of the third phase current of the low voltage winding of the power transformer and the input of the same phase of the current relays 3, the secondary windings of the saturable transformers 8 and 9 are shunted by active-capacitive chains 10 and 11, the output elements 14 of the power direction relays 4 and 5 are connected to the disconnecting circuit of the power transformer.

Capacitor 12 and resistor 13 perform an overvoltage protection function.

Capacitors 6 and 7 provide the maximum torque at relays 4 and 5 of the power direction. Fast-sinking transformers 8 and 9 are supplied to the voltage windings of relays 4 and 5 with practically constant voltage regardless of the magnitude of the short-circuit current.

The windings 15-17 of the current relays 3 and their circuit for switching on the difference of phase currents,

5 depicted in FIG. 2, are made as in the prototype.

The device works as follows.

0In normal operation of power

transformer in the direction of power from the winding to the winding of the lower voltage power transformer or vice versa currents at the outputs of transformers 1 and 2 current

5 coincide in sign, therefore the sign and currents in the current winding and the voltage winding of the relays 4 and 5 of the power direction coincide in sign and their output elements 14 do not work. Current relays do not work either.

0 3, since the difference of currents in the windings 15-17 fixed by the relay is close to zero, the sign and currents in the current winding and the voltage winding of relays 4 and 5 of the power direction and their output elements coincide

5 do not work. The current relays 3 do not work either, since the difference of the currents in the windings 15-17, which is fixed by the relay, is close to zero.

With a short circuit on the findings

0 or between the windings of the power transformer, the currents at the outputs of the transformers 1 and 2 of the current are opposite in sign, as are the opposite in sign and currents in the current winding and the voltage winding of relays 4 and 5

5 power directions. Their output elements 14 are triggered. Such current relays 3 operate, the windings 15-17 of which fix the sum of the indicated currents.

Testing a transformer (i.e. its

0 unilateral activation is accompanied by magnetizing current surges. In connection with this, the current in the current relays 3 increases in comparison with the normal mode, the response threshold of which must be chosen higher than the indicated current.

However, in this case there is no current in the current winding or in the voltage winding of the relays 4 and 5 of the power direction, so its threshold can be accepted below the specified current level.

When a power transformer is turned on for a short circuit, there is no current at the output of one of the transformers 1 or 2, therefore there is no current in the current winding or in the voltage winding of relays 4 and 5 of the power direction and their output elements 14 do not operate.

However, at the inputs of the current relays 3, a current is generated, which causes the relays to trip the power transformer.

During short coils in windings of a power transformer, the level of currents at the outputs of transformers 1 and 2 may be lower than the levels of currents when testing a power transformer. Therefore, the current relay 3 in this case may not work. However, the relays 4 and 5 of the power voltage, having a lower response threshold, provide, through their output elements, the disconnection of the damaged power transformer.

Thus, due to the use of a directional relay, an increase in the sensitivity of the device to winding short circuits and windings of a power transformer is achieved.

Claims (1)

Claims of the Invention Protection device of a power double-washing transformer with two-sided power supply, comprising two three-phase current transformers, one of which, connected in a triangle, is installed on the side of a high voltage winding, and the other, connected in an incomplete star, on the side of a power winding transformer, and the number of phases - current relays connected to the difference of the phase currents of one and the other current transformers, characterized in that. In order to increase the sensitivity of protection to winding short circuits of the windings of a power transformer, two power relays, two capacitors, two two-winding saturable transformers, two active-capacitive chains of series-connected resistors and a capacitor, and the first winding A power direction relay is connected between the current transformer output of one phase of the winding of the higher voltage of the power transformer and the input of the same phase of the current relay, and the current the coil of the second power direction relay is connected between the output of the current transformer of the third phase of the high voltage winding of the power transformer and the input of the same phase of the current relays, the voltage winding 0 of the first power direction relay through the first capacitor is connected to the secondary winding of the first saturating transformer, the primary winding of which is connected between the output of the current transformer of one phase of the low voltage winding of the power transformer and the input of the same phase of the current relay, and the voltage of the second relay of the power direction through the second capacitor is connected to the secondary winding of the second saturating transformer, the primary winding of which is connected between the output of the third-phase current transformer bmotki Low voltage power 5 of the transformer and the input of the same phase of the current relay, the secondary windings of the saturable transformers are shunted by active-capacitive chains, the output elements of the power direction relay are connected to the disconnecting circuit of the power transformer. 15 X L sixteen 17 j FIG. 2