FR2762924A1 - PNEUMATICALLY CONTROLLED DISCONNECTOR FOR A HIGH VOLTAGE SHIELDED STATION - Google Patents

Abstract

A disconnector 10 for a high voltage and SF6 shielded substation comprises an enclosure 20 subdivided by an insulator 22 into a first compartment 64 containing a first fixed contact 12, and a second compartment 26 containing a second fixed contact 14. The insulator 22 is equipped with a conductive socket 28 inside which moves the movable contact 30 shaped as a double-acting piston sensitive to the differential pressure of the gas in the first compartment 64 and the second compartment 26 adjacent, to establish either the closed position, ie the open position of disconnector 10. The same SF6 gas is used for isolation and for controlling the disconnector.

Description

PNEUMATICALLY CONTROLLED DISCONNECTOR FOR AN ARMORED STATION

HIGH VOLTAGE

  The invention relates to a disconnector for a high voltage, gas-insulated shielded substation, comprising a sealed metal casing filled with insulating gas under pressure and with high dielectric strength, in particular sulfur hexafluoride SF6, and containing at least a sectioning pole comprising a first fixed contact and a second fixed contact cooperating with a movable contact for

  define an isolation interval in the disconnector open position.

  The line or switch disconnectors used in high-voltage shielded substations make it possible, on the one hand, to carry out, by appropriate maneuvers, different connection diagrams depending on the type of electrical network, and on the other hand to isolate for

  security reasons, certain parts of the circuit in the event of intervention on the network.

  To carry out these maneuvers, each disconnector is generally equipped with a mechanism with manual control or remote control by a geared motor for the mechanical actuation of the movable contact between the open and closed positions. The use of such disconnectors in shielded substations requires, during testing or maintenance operations, cutting off the main artery of the network, and earthing on both sides of the circuit breaker. Such a test process uses two line disconnectors, and two earthing switches, as shown in document US-A-3987260. The different commands of the line and earthing switches must be synchronized. The cost of manufacturing and maintenance

of such a post is high.

  The object of the invention is to simplify the control of a high disconnector

  voltage using the energy of the shielded station isolation gas.

  The disconnector according to the invention is characterized in that - the casing of the disconnector is subdivided by an insulator into a first compartment containing the first fixed contact, and a second compartment containing the second fixed contact, - the insulator is equipped with a conductive sleeve inside which moves the movable contact shaped according to a double-acting piston sensitive to the differential pressure of the gas in the first compartment and the adjacent second compartment to establish either the closed position or the position disconnector opening. According to a characteristic of the invention, the movable contact of the disconnector is provided with an annular flange having a diameter slightly greater than that of the rod of the movable contact, and intended to slide in leaktightness inside the socket to guarantee the between the two compartments when the contact is moved

  movable between the open position and the closed position.

  The cylindrical sleeve has two stops cooperating with the flange at the end of the travel movement of the movable contact, the axial offset between the two stops being

  slightly greater than the isolation interval.

  According to another characteristic, the first compartment is in communication with a reservoir containing a compressor, and control means for adjusting the

  gas pressure compared to that prevailing in the second compartment.

  According to a preferred embodiment, the first compartment is formed for the expansion volume of a circuit breaker associated with the envelope of the disconnector, the circuit breaker having a contact in electrical connection with a feeder, and another contact

  in electrical connection with the first fixed contact of the disconnector.

  The circuit breaker is actuated by a pneumatic control mechanism housed in the tank, the pressure of the isolation gas in the expansion volume of the circuit breaker being always maintained by the compressor at a value greater than that of the second compartment of the disconnector during operation normal from

post.

  The same compressor is thus used for the operation of the circuit breaker and the closing switch control. The same SF6 gas is used for insulation, breaking of the arc in the circuit breaker, and combined control of the circuit breaker and the

disconnector.

  Other advantages and characteristics will emerge more clearly from the description

  which follows of an embodiment of the invention, given by way of nonlimiting example and shown in the appended drawings in which FIG. 1 is a schematic sectional view of a pneumatically controlled disconnector according to the invention, the disconnector being shown in the open position, - Figure 2 shows an identical view to Figure 1 when the disconnector is in the closed position, - Figure 3 shows a view of a bay of an armored substation comprising an assembly pneumatically operated disconnector and circuit breaker,

  - Figure 4 is a detail view on an enlarged scale of the disconnector of Figure 3.

  With reference to FIGS. 1 and 2, a line disconnector 10 of a shielded high-voltage substation with gas isolation comprises at least one sectioning pole comprising a first fixed contact 12 tubular, and a second fixed contact 14 tubular, carried respectively by support insulators 16, 18 spaced one of

  the other along the axial direction of a sealed metallic envelope.

  The interior of the envelope 20 is filled with insulating gas with high dielectric strength, in particular sulfur hexafluoride SF6, and is subdivided by an insulator 22

  intermediate in two adjacent compartments 24, 26.

  The insulator 22 is crossed axially by a cylindrical and conductive sleeve 28, inside of which is slidably mounted a movable contact 30 in the form of a cylindrical rod. The intermediate part of the movable contact 30 is equipped with an annular flange 32 having a diameter slightly greater than that of the contact rod

mobile 30.

  The flange 32 acts as a double-acting piston displaceable in alternating translation inside the sleeve 28 between two end stops 34, 36, which are formed by curved parts formed at opposite ends of the sleeve 28. The flange 32 is provided with seals cooperating with the socket 28 to guarantee sealing between the two compartments 24, 26 when the movable contact 30 is in the open position (FIG. 1) or in the closed position (FIG. 2) and

  also during its movement between these two positions.

  Each fixed contact 12, 14 is shaped according to an annular ring having an internal diameter, corresponding to the external diameter of the movable contact 30. The first fixed contact 12 is cantilevered by a bell-shaped conductive member 38, secured to the support insulator 16, and being in the first compartment 24. In a similar manner, the second fixed contact 14 is carried in cantilever by a bell-shaped conductive member 40 fixed to the other insulator

  support 18, and arranged in the second compartment 26.

  Tubing 42 connects the first compartment 24 of the envelope 20 to a reservoir 44

  containing a compressor 46, and a control solenoid valve 48.

  The displacement of the movable contact 30 takes place by means of the differential pressure of the gas contained in the two compartments 24, 26 of the envelope 20. When the gas pressure SF6 inside the first compartment 24 is greater than that prevailing in the second compartment 26, the piston of the collar 32 drives the movable contact 30 to the right, so as to bring it to the end of the closing stroke in engagement with the second fixed contact 14 (FIG. 2). The disconnector 10 is

then in the closed position.

  The disconnector 10 is opened when the pressure of the SF6 gas inside the second compartment 26 is higher than that generated in the first compartment 24. The piston of the flange 32 is then biased to the left inside the socket 28, and causes the sectioning with the formation of a

  isolation interval 50 (Figure 1).

  The pressure drop in the first compartment 24 is obtained following the excitation of the solenoid valve 48 causing a gas discharge to the reservoir 44 through the

tubing 42.

  Switching on the compressor 46 causes the pressure in the first compartment 24 to rise to a predetermined threshold so as to cause the disconnector to close 10. The position of the movable contact 30 is bistable, the position change being effected quickly as soon as the start of the displacement race in a

one way or the other.

  In the embodiment of Figures 3 and 4, the disconnector 10 is associated with a circuit breaker 52 equipped with a pneumatic control mechanism 54 of the type described

  in patent EP-A-465377 of the applicant.

  Each pole of the circuit breaker 52 includes a pair of separable contacts 56, 58, and an arc extinguishing device 60 made active when the contacts 56, 58 are separated. One of the contacts 58 is connected to a feeder 62, while the other

  contact 56 is in electrical connection with the first fixed contact 12 of the disconnector 10.

  The expansion volume 64 of the circuit breaker 52 corresponds in this case to the first compartment 24 of the device in FIGS. 1 and 2, and is in communication with the reservoir 44 containing the compressor 46. The second compartment 26 of the disconnector 10 is separated from the volume expansion 64 by the support insulator 22 carrying the movable contact 30 bistable, which is movable between the two stops of the conductive sleeve 28. The other two insulators 16, 18 are not necessary, the second fixed contact 14 being electrically connected to a phase of a busbar 70

three-phase power supply.

  In normal operation of the high-voltage shielded substation, the pressure of the isolation gas inside the expansion volume 64 of the circuit breaker 52 is of the order of 6 bars, while the pressure of the gas in the second compartment 26 of the disconnector 10 is approximately 4 bars. Such a pressure differential permanently keeps the disconnector 10 in the closed position so as to guarantee the supply of the circuit breaker 52 and of the outgoing feeder 62. The pressure of the isolation gas in the expansion volume 64 is adjusted by the compressor 46 during operation

  normal, or during a cut-out made by circuit breaker 52.

  The excitation of the solenoid valve 48, possible after the opening of the circuit breaker 52 causes a drop in gas pressure in the expansion volume 64 causing the

  separation of the contacts 30,14 of the switch 10

  The disconnector 10 recloses as soon as the compressor has re-inflated the

  expansion volume 64 at a pressure greater than 4 bars.

  The disconnector 10 of Figures 3 and 4 is arranged according to a line disconnector, which is associated with a grounding disconnector 72 with manual control. The earthing switch 72 comprises a contact pin 74 sealingly traversing an orifice 76 of the metal casing 20 in a direction perpendicular to the movable contact 30. The pin 74 is at ground potential, and its free end is likely to enter the expansion volume 64 to engage in a hole

  the conductive sleeve 28 carried by the support insulator 22.

  When the earthing switch 72 is in the closed position (Figure 4), the circuit breaker is earthed on the side of the busbar 70. The outlet 62 also includes a quick closing earthing switch 78 to ensure the

outlet grounding 62.

  The solenoid valve 48 is not necessary when the disconnector 10 is used only

  safety device in the event of intervention on the circuit breaker 52.

  It is clear that the movable contact 30 in translation of the disconnector 10 could be

  replaced by a pivoting movable contact to constitute a rotary disconnector.

Claims (10)

  1. Disconnector for a high-voltage, gas-insulated shielded substation, comprising a sealed metal casing (20), filled with insulating gas under pressure and with high dielectric strength, in particular sulfur hexafluoride SF6, and containing at least one isolating pole comprising a first fixed contact (14) and a second fixed contact (16) cooperating with a movable contact (30) to define an isolation gap (50) in the open position of the disconnector (10), characterized in that - the casing (20) of the disconnector (10) is subdivided by an insulator (22) into a first compartment (24, 64) containing the first fixed contact (12), and a second compartment (26) containing the second fixed contact (14), - the insulator (22) is fitted with a conductive sleeve (28) inside which the movable contact (30) moves, shaped according to a double-acting piston sensitive to differential pressure gas in the first compartment ment (24, 64) and the second compartment (26) adjacent to establish either the closed position or the position the disconnector (10).   2. Disconnector according to claim 1, characterized in that the movable contact (30) of the disconnector (10) is provided with an annular collar (32) having a diameter slightly greater than that of the rod of the movable contact (30), and intended to slide sealingly inside the bushing (28) to guarantee sealing between the two compartments (24, 64, 26) when the movable contact (30) is in the open position or in the position of closing and also during its movement between these two positions.   3. Disconnector according to claim 2, characterized in that the cylindrical sleeve (28) has two stops (34, 36) cooperating with the flange (32) at the end of the travel movement of the movable contact (30), the axial offset between the two stops   (34, 36) being slightly greater than the isolation interval (50).   4. Disconnector according to one of claims 1 to 3, characterized in that the first   compartment (24, 64) is in communication with a reservoir (44) containing a compressor (46), and control means for adjusting the pressure of the gas by   compared to that prevailing in the second compartment (26).   5. Disconnector according to claim 4, characterized in that the control means comprise at least one solenoid valve (48) intended to ensure the escape of the gas from the first compartment (24, 64) towards the reservoir (44) during the phase the disconnector (10).   6. Disconnector according to one of claims 1 to 5, characterized in that the first   compartment (64) is formed for the expansion volume of a circuit breaker (52) associated with the casing (20) of the disconnector (10), the circuit breaker (52) having a contact (58) in electrical connection with a feeder (62), and another contact (56) in connection   electric with the first fixed contact (12) of the disconnector (10).   7. Disconnector according to claim 6, characterized in that the circuit breaker (52) is actuated by a pneumatic control mechanism (54) housed in the tank (44), the pressure of the insulating gas in the expansion volume ( 64) of the circuit breaker (52) being always maintained by the compressor (46) at a value greater than that of the second compartment (26) of the disconnector (10) during normal operation of the post.   8. Disconnector according to claim 7, characterized in that the casing (20) is provided with an orifice (76) for the passage of a contact pin (74) of an earthing disconnector (72) , said pin being connected to the earth potential, and extending in a direction perpendicular to the movable contact (30) of the disconnector (10) to engage during the earthing, in a hole of the socket (28) on the side of expansion volume (64).   9. Disconnector according to one of claims 1 to 8, characterized in that the contact   mobile (30) is formed by a bistable cylindrical rod mounted to slide alternately between the closed and open positions to constitute a line disconnector or busbar.   10. Disconnector according to claim 1, characterized in that the movable contact (30)   is pivotally mounted on the sleeve (28) to form a rotary disconnector.