CN2342377Y

CN2342377Y - Fault monitor for high voltage power supply cable network earthing

Info

Publication number: CN2342377Y
Application number: CN 98232510
Authority: CN
Inventors: 李选文
Original assignee: Caihong Color CRT General Factory
Current assignee: Caihong Color CRT General Factory
Priority date: 1998-03-10
Filing date: 1998-03-10
Publication date: 1999-10-06
Anticipated expiration: 2008-03-10

Abstract

The utility model relates to a fault monitoring device for high voltage power supply cable network earthing. The utility model comprises a zero-sequence mutual inductor and a zero sequence current sensing return circuit of the secondary side of the zero-sequence mutual inductor, and the zero-sequence mutual inductor is installed on each power supply cable. The utility model has a key structure that a secondary inducting luminous-display circuit of the zero-sequence current induction return circuit is added; the secondary inducting luminous-display circuit is composed of secondary induction branch circuits which are connected in parallel and are arranged on the zero-sequence current induction return circuit; each secondary induction branch circuit is composed of a mutual inductor, a rectifying diode and a luminous diode which are connected in series. The utility model with simple structure can finish the positioning display of the fault cable; thus, the fault can be processed in time, and the power-off time caused by the fault of the power supply network can be lowered.

Description

High voltage supply cable system earth fault monitoring arrangement

The utility model is a kind of high voltage supply cable system earth fault monitoring arrangement.

In the electric power system of 6～10KV or 35KV, generally all adopt three-phase supply neutral point O ' earth-free (as shown in Figure 2) or neutral point O ' power through the mode of arc suppression coil Q ground connection (as shown in Figure 3).When this electric power system is normally moved, the power supply neutral point O ' and end line A, B, C between phase voltage U _A, U _B, U _CBe (be equal and opposite in direction, phase differential is 120 °) of balance, line voltage U between each end line _AB, U _BC, U _CAIt is phase voltage Doubly.When a phase ground connection takes place in service cable, as shown in Figure 4, suppose that the C of service cable L1 at the D point earth fault takes place, then the C phase-to-ground voltage is zero, the voltage-to-ground of A, B two-phase raises

Doubly.At this moment, the value and the phase differential of each phase remain unchanged, and still can power to the three-phase consumer.But,, can cause certain prestige association to the insulation of electrical equipment in the system because the voltage-to-ground of A, B two-phase raises, also may cause the puncture over the ground of service cable A, B two-phase, cause the two phase ground short circuit, cause switch trip, line outage, therefore, must in time find and handle.In prior art, adopt a kind of zero-sequence current protection device to finish the supervision of service cable grid grounding fault usually.Owing to just form electric capacity when being separated with insulating medium in the middle of any two conductors, therefore, exist in each service cable alternate electric capacity and relatively between electric capacity, suppose to ignore alternate electric capacity, relatively between electric capacity as shown in Figure 3.When system normally moves, because phase voltage is symmetrical, so the capacitive earth current of three phases

Vectorial sum be zero, each voltage relatively just equals phase voltage.In case system's generation earth fault, the C that supposes service cable L1 as shown in Figure 4 takes place is when D point ground connection, and the current potential of C phase is zero, and the capacitive earth current of C phase also is zero, the capacitive earth current I of A, B two-phase among service cable L1～Ln _A1～I _An, I _B1～I _BnAll to flow back into power supply, then in earthing cable L1, will have bigger uneven capacitive earth current to flow through by earth point D.The zero-sequence current protection device utilizes this characteristic exactly; on each service cable, all be provided with a zero-sequence transformer H1～Hn, and the secondary coil of each zero-sequence transformer all constitutes a zero-sequence current loop inductance as shown in Figure 5 with a relay series connection.Again referring to Fig. 4, when earth fault takes place in the C of service cable L1 mutually, the uneven capacitive earth current I among the L1 _A1, I _B1One goes into one and goes out through the D point to flow back to power supply in the iron core of zero-sequence transformer H1, therefore, in H1 by I _A1, I _B1The magnetic flux that produces is repealed by implication, and by the next uneven capacitive earth current I of other service cable L2～Ln _A2～I _AnAnd I _B2～I _BnWill be in the iron core of zero-sequence transformer H1 two go into one and go out through the D point to flow back to power supply, this imbalance capacitance current will produce bigger magnetic flux in the iron core of zero-sequence transformer H1, make its secondary inductive coil output induced potential, the electric current that this induced potential produces makes the actuating of relay and provides fault-signal.But, as can be seen from Figure 4, the uneven capacitive earth current I among non-failure cable L2～Ln _A2, I _B2... I _An, I _BnAlso will be in the iron core of its zero-sequence transformer two go into one and go out after the C line arrives the D point, flow back to power supply then, therefore, so the non-uneven capacitive earth current in the cable also can make its zero-sequence transformer produce induced potential and provide fault-signal simultaneously.Like this, though can in time find fault, can't judge that cable breaks down.In order to find out failure cable, commonly usedly to seek by the operate a switch mode of outage of road, this has not only incured loss through delay the time of fault handling, and the user who returns electric power system causes damage.

The purpose of this utility model is the problem that can not locate at fault alarm in the prior art, but a kind of high voltage supply cable system earth fault monitoring arrangement of locating alarming is provided.

As seen in Figure 4, the uneven capacitive earth current that flows through on the failure cable L1 is other non-failure cable L ₂～L _nThe summation of the uneven capacitive earth current of middle A, B heart yearn, and each non-failure cable L ₂～L _nOn what flow through is the uneven capacitive earth current of own A, B heart yearn.Obviously, the uneven capacitive earth current that flows through on the failure cable much bigger than on the non-failure cable.According to this characteristic, the utility model adopts secondary induced potential relative method to realize the failure location warning, its concrete solution is as follows: this device comprises the zero-sequence current loop inductance of the zero-sequence transformer that is installed on each service cable and this zero-sequence transformer secondary side, its key structure is: the inducing luminous display circuit of secondary of setting up a zero-sequence current loop inductance, this display circuit is made of the secondary induction branch road parallel connection that is located on each zero-sequence current loop inductance, a described secondary induction route mutual inductor, commutation diode, the light emitting diode series connection constitutes.

By above-mentioned solution as can be seen, when in the power supply grid during a certain service cable generation earth fault, to produce bigger induction current in the zero-sequence current loop inductance on this service cable, mutual inductor on the branch road of secondary induction simultaneously also will produce bigger induced potential, this induced potential makes light emitting diode bright after rectifies, simultaneously, this induced potential is also clamped in low level with other secondary induction branch road, light emitting diode on other secondary induction branch road can not be lighted, so just finished the locating and displaying of failure cable.Superiority of the present utility model is to have finished with simple circuit configuration the locating and displaying of failure cable, and fault can in time be handled, and greatly reduces the fault outage time of power supply grid.

Describe concrete structure of the present utility model and principle below with reference to the accompanying drawings in detail.

Fig. 1, circuit theory diagrams of the present utility model.

The three-phase supply power supply the principle figure of Fig. 2, isolated neutral.

The three-phase supply power supply the principle figure of Fig. 3, neutral by arc extinction coil grounding.

Capacitive earth current distribution schematic diagram when Fig. 4, supply network generation earth fault.

The zero-sequence current loop inductance schematic diagram of Fig. 5, zero-sequence transformer secondary side.

Referring to Fig. 1, the zero-sequence current loop inductance of described each service cable is made of a zero-sequence transformer (1) and relay (2) series connection.One end and the power supply of relay (2) normally opened contact join, another termination fault alarm (3).A described secondary induction mutual inductor of route (6), commutation diode (7) and light emitting diode (8) series connection constitute.The inducing luminous display circuit of this secondary induction described secondary of branch road formation parallel with one another.Also have the audible alarm function in order to make in the inducing luminous display circuit of this secondary, can be in the inducing luminous display circuit of this secondary the relay switch (4) of a squealer in parallel or a squealer.Suppose that earth fault as shown in the figure takes place service cable L1, the induced potential maximum of mutual inductor H1 ' output then, this induced potential makes light emitting diode LD1 bright, the squealer sounding after the rectification of commutation diode D1; This induced potential is also clamped in low level with other induction branch road simultaneously, and the commutation diode on other induction branch road is ended, and its light emitting diode does not work.Thereby finish the locating and displaying and the audible alarm of earth fault cable.

Claims

1, high voltage supply cable system earth fault monitoring arrangement, the zero-sequence current loop inductance that comprises the zero-sequence transformer that is installed on each service cable and this zero-sequence transformer secondary side, it is characterized in that: the inducing luminous display circuit of secondary of setting up a zero-sequence current loop inductance, this display circuit is made of the secondary induction branch road parallel connection that is located on each zero-sequence current loop inductance, and a described secondary induction route mutual inductor, commutation diode, light emitting diode series connection constitute.

2, high voltage supply cable system earth fault monitoring arrangement as claimed in claim 1 is characterized in that: the relay switch of a squealer in parallel or a squealer in the inducing luminous display circuit of described secondary.