EP0127531A1 - Hydraulically operating system for electric circuit breakers - Google Patents

Abstract

On the parts (19) of the hydraulic control circuit, which are sometimes under pressure, sometimes unpressurized, is connected an assembly E comprising a reduced pressure regulator (33) and a low-capacity compensating hydraulic accumulator (37) which replenishes oil at reduced pressure the portions of the circuit lacking oil or filled with emulsified oil following the depressurization operations. The invention makes it possible to reduce the response times to circuit breaker closing orders.

Description

The present invention relates to oleopneumatic controls for electric circuit breakers.

It is known that these commands essentially comprise: a hydraulic actuator for actuating the movable contact of a circuit breaker; one or more high pressure oleopneumatic accumulators, of the order of 200 to 400 bars, a valve supply / purge valve system, which selectively connects the working chamber of the actuator to the accumulator or to a low pressure purge enclosure; and a hydraulic circuit for sending orders controlling the switching, in the feed position or in the purge position, of the aforementioned valve system.

The hydraulic circuit for sending orders is selectively put under high pressure, to bring the valve system of the jack to the supply position, that is to say to bring the circuit breaker to the on position; or it is selectively vented to return the valve system of the actuator to the purge position, that is to say to return the circuit breaker to the tripped position.

The hydraulic circuit for sending orders is placed under the control of a so-called "operational block" control station, of well known construction, which, from fugitive electrical engagement or trigger orders acting on two engagement or trigger electro-valves, puts under high pressure or else purges the hydraulic circuit for sending orders.

The actuator of the moving contactor of the circuit breaker is returned to the position corresponding to the tripping of the circuit breaker, by the elastic tripping means (mechanical or pneumatic spring), the jack being held, in the position corresponding to the engagement of the circuit breaker. , by maintaining the HP in the cylinder's working chamber.

An oleopneumatic control of the aforementioned type is for example described and represented in the book "Technical Engineering" Volume "Electricity", page D 657-5.

As is well known, and as seen from the above, a number of the hydraulic lines of a circuit breaker control (and, among them the lines for sending orders) are alternately subjected to HP or are "unpressurized" (venting substantially at atmospheric pressure).

Given the high pressures used (200 to 400 bars), for which the oil behaves like a compressible fluid, and given the very short operating times required for circuit breakers, the passage of a pipeline from the situation "into pressure "to the situation" without pressure "gives rise to phenomena of depression of certain volumes of oil, due to the inertia of the volumes of oil set in rapid motion (several tens of meters / second which act at like a liquid piston.

It follows that, in at least some of their parts, the pipes, and in particular the pipes for sending orders, have empty volumes of oil or containing emulsified oil.

For the next engagement maneuver which is carried out by repressurizing the previously purged pipe, the pipe behaves as if it were partially filled with an elastic fluid and the response time to the hydraulic pressurization signal is extended , indefinitely.

For a few years, we have been looking for shorter and shorter breaker operating times, of the order of a few milliseconds between sending the order and the start of actuation of the jack, and we have been looking for even more constant times. reproducible in all operating cases.

This is particularly important for groups of circuit breakers or circuit breaker modules to be operated simultaneously (circuit breakers on the three phases of a network or circuit breakers connected in series on the same phase).

This is also important in the so-called "synchronous engagement" in which the engagement must be carried out at a precise point on the sinusoid of the current voltage, thereby requiring knowledge of the response time of the command.

In the event that a sufficient time interval elapses between a triggering maneuver and the next engaging maneuver, a certain equilibrium has the time to recover more or less slowly in the pipes for sending orders. However, it is common in modern installations for the time interval between the sending of a trip order and the sending of the next trip order not to exceed about 3 / 10th of a second. then at this point in the pipes of empty oil or oil filled volumes emulsified, so that the response time can be doubled, or even more, and that the response times can be very different between several circuit breakers controlled from the same trip signal.

It is in particular this defect that the invention proposes to eliminate.

It should be noted on the other hand that the harmful phenomena described above, appearing in the pipes as a result of pressurization or pressurization, can also cause re-entry of air, due to seals which are tight in oil but not airtight. In the case of a long period in the triggered position, these air inflows are detrimental to the delays and the reproducibility of the delays of the first engagement maneuvers.

Finally, the volumes of emulsified oil contained in the pressureless pipes are returned throughout the hydraulic control circuit, as and when all the switching operations, where they can have harmful effects, for example waves pressure or the impossibility of performing hydraulic sequences in series.

The invention overcomes these latter drawbacks.

The subject of the invention is an oleopneumatic control of the aforementioned type comprising, in addition, a pressure reducer delivering a reduced pressure PR from the high pressure HP of the accumulator, as well as a compensator accumulator at reduced pressure, of low capacity, compared to that of the HP accumulator, recharged by the regulator and connected to the hydraulic circuit for sending orders from the oleopneumatic control.

Preferably the compensating accumulator is connected to the hydraulic circuit for sending orders in the vicinity of the upstream end of a part of this circuit, considering the direction of circulation of the oil in this part of the circuit when said circuit goes from the "pressurized" situation to the "pressurized" situation.

Thanks to this arrangement, the compensating accumulator directly replenishes non-emulsified oil with the precise locations of the circuit where voids or oil emulsions appear, so that the "oil-filled" situation is restored almost instantaneously in the circuit which is ready to receive a new switch-on signal.

In the common case of a hydraulic control in which the HP supplied by the main accumulator is of the order of 200 to 400 bars, the regulator and the compensating accumulator are adjusted for a reduced pressure of between 2 and 10 bars, or on the order of 20 to 100 times lower than the pressure of the main accumulator.

In the case where the compensating accumulator is connected, in all the operating configurations of the installation, to a part of the hydraulic circuit capable of being put under HP, a non-return valve is interposed preventing the return of the HP to the compensating accumulator.

It has been indicated in the foregoing that the compensating accumulator has a low capacity compared to the main accumulator. This capacity can be for example 100 to 1000 times more low. Thus, the capacity of the compensating accumulator can be of the order of a few cubic centimeters to a few tens of cubic centimeters, while the capacity of the main HP accumulators is commonly from a few cubic decimetres to a few tens of cubic decimeters.

Of course, the same compensating accumulator can be connected at several points of the circuit, the most likely to give rise to the appearance of an emulsion, or else several compensating accumulators can be provided for the same command.

Oleopneumatic controls for circuit breakers often include, as is well known, one or more hydraulic relay valves on the hydraulic circuit connecting the "operational block" to the supply / bleed valve system of the jack.

According to one embodiment of the invention, the compensating accumulator can be connected not only to the regulator, to be recharged by the latter, but also to one of the chambers of at least one of the relay valves receiving the purge oil from the order sending pipe when the latter is "depressurized", whereby the compensating accumulator is also partially recharged by the purge oil discharged during tripping operations.

The reduced pressure compensator accumulator is preferably a low inertia accumulator, having a response time for the supply of the compensating oil. Preferably, the compensating accumulator is of the membrane type, with a short stroke, the membranes being subjected to the action of a mechanical spring, by means of a support plate.

• La figure 1 est une représentation schématique d'une commande oléopneumatique pour disjoncteur équipée d'un système compensateur suivant l'invention.
• La figure 2 est une variante de la figure 1 dans laquelle la canalisation de liaison entre le bloc de commande et le vérin du disjoncteur est, à la fois, une canalisation d'envoi d'ordres hydrauliques et une canalisation de transmission de puissance.
• La figure 3 est une autre variante de la figure 1 dans laquelle le système compensateur suivant l'invention réalimente les valves relais du circuit hydraulique.
• La figure 4 est une vue en coupe d'un accumulateur compensateur à membrane et à ressort.

The invention will be better understood on reading the detailed description which follows and on examining the appended drawings which represent, by way of nonlimiting examples, several embodiments of the invention.

• FIG. 1 is a schematic representation of an oleopneumatic control for a circuit breaker equipped with a compensating system according to the invention.
• Figure 2 is a variant of Figure 1 in which the connecting pipe between the control unit and the circuit breaker cylinder is, at the same time, a pipe for sending hydraulic orders and a pipe for power transmission.
• FIG. 3 is another variant of FIG. 1 in which the compensating system according to the invention replenishes the relay valves of the hydraulic circuit.
• Figure 4 is a sectional view of a diaphragm and spring compensator accumulator.

FIG. 1 shows the essential elements of an oleopneumatic control of known type, for an electric circuit breaker. This command includes: a hydraulic cylinder 1 for actuating the movable contact 3 from a circuit breaker to the fixed contact 4; a main high pressure oleopneumatic accumulator 5; a supply / purge valve system 7 for selectively connecting the working chamber 9 of the jack 1 either to a low-pressure enclosure 11, in the tripped position of the circuit breaker shown in FIG. 1, or to the accumulator 5,, for bringing and keep the circuit breaker in the on position. The cylinder is returned to the triggered position by permanent elastic means such as a spring 13 or the elastic pressure of the accumulator 5 brought into the upper chamber 9 'of the jack by a pipe 13' indicated in broken lines in FIG. 1. The supply / purge system 7 comprises a hydraulic actuator 15 for the supply / purge valve which brings the switching member 17 of the valve into the supply position 17 'when it is subjected to the high hydraulic pressure supplied by a pipe. 19 and returns the switching member 17 to the bleed position shown in solid lines when said actuator is no longer subjected to the high pressure. Finally, the installation comprises, in a conventional manner, a sending station of order 21, called "operational block", which can be located at a distance from the circuit breaker, and which comprises a solenoid for engagement 23 and an electrovalve for tripping. 25, which control the switching of a valve 27. This valve 27, in the solid line position, connects to a low pressure enclosure 29 the connecting pipe 19 between the operating unit and the valve system 7, while, in position 27 ′, the pipe 19 is connected to the high pressure supplied either by an additional accumulator provided for the operational block, or by the main accumulator 5 which is connected to the operational block by a pipe 31.

The operation of such an installation is well known and it suffices to recall that, in the case shown in FIG. 1, the pipe 19, which can be very long, is only a pipe for sending orders by "placing pressure "or" depressurization ", while the high-flow hydraulic power required to supply cylinder 1 is supplied directly by the main accumulator 5.

To bring the circuit breaker into the latched position and keep it there, the pipe 19 is put under the high pressure of the main accumulator 5, for example 200 to 400 bars. To bring the circuit breaker into the tripped position, the pipe 19 is vented, substantially at atmospheric pressure. During this maneuver, the oil contained in the line 19 decompresses, as has been explained previously, and at least part of the line 19 is empty of oil or filled with emulsified oil.

If the following engagement order, by repressurizing the line 19, is given within a short time, the line 19 will behave as if it were filled with an elastic fluid, so that the response time of l actuator 15 will be considerably increased and variable from one operation to another.

According to the invention, there is provided a "regulator / compensator accumulator" E assembly which comprises a regulator 33 the high pressure side of which is connected to the main accumulator 5 by the pipe 31 and which delivers by its outlet 35 a reduced pressure PR. The assembly E also comprises a compensating accumulator 37 at reduced pressure and at low capacity which is recharged with oil at the pressure PR by the pressure reducer and which is connected, by a pipe 39 to the hydraulic circuit for sending orders 19.

A non-return valve 41, mounted on the pipe 39, prevents the high pressure, present in the pipe 19 in the engaged position of the circuit breaker to gain the reduced pressure portion PR of the hydraulic circuit 33, 35, 37.

Preferably, the pipe 39 is connected to the pipe 19 in the vicinity of the upstream end 43 thereof, if one considers the displacement of the oil when the circuit 19 passes from the "pressure" situation to the " off pressure ", this end 43 being the most subject to the phenomenon of lack of oil.

Thanks to the assembly E, the line 19, which is partially empty of oil (or filled with emulsified oil) when pressurized, is quickly replenished and replenished with oil in the liquid state, under pressure PR, by the compensating accumulator 37, which is immediately recharged with oil by the regulator 33.

To avoid that, in the tripped position, the compensating accumulator 37 and the regulator 33 do not flow continuously, there is provided, on the drain pipe 45 of the operating unit 21, a check valve 47, calibrated at a pressure slightly higher than the PR pressure.

Of course, one can provide several identical sets E, to replenish several points of the hydraulic circuit most likely to suffer from a lack of oil or the presence of emulsified oil. It is also possible, from a single set E, to replenish several points of the hydraulic circuit.

The volume of the portions of the hydraulic circuit which empty of oil at the time of depressurization is relatively small, this is why it suffices with a compensating accumulator 37 of small capacity, for example a few cubic centimeters to a few tens of cubic centimeters (about 1000 times less than the capacity of the main battery 5).

On the other hand, it has been observed that only a low "Reduced Pressure" is sufficient to refuel the empty portions of oil. Thus, for the compensating accumulator 37 and for the regulator 33, it suffices to provide a reduced pressure of the order of 2 to 10 bars, while the high pressure of the accumulator 5 is of the order of 200 at 400 bars.

Finally, it is advantageous for the compensating accumulator 37 to have low inertia, to quickly compensate for the lack of oil. This is why, as will be seen with reference to FIG. 4, a membrane accumulator with a short stroke is preferably chosen, the membrane of which is stressed by a mechanical spring bearing, on a support plate, against the membrane.

There is shown in Figure 2 another known hydro-pneumatic control system for circuit breaker which includes the same essential elements as that of Figure 1 but in which the connecting pipe 19 between the operating block 21 and the supply-purge valve 7 of the actuator 1 is not only a pipe for sending orders to the valve 7 (by "pressurizing" or "depressurizing") but also serves as a power line for supplying the working chamber 9 of the actuator 1.

An example is shown for the valve 7, a known valve of the so-called "rapid vent" type, in which the portion 15, forming a piston, of the purge valve 49 constitutes the hydraulic actuator of the valve 7.

The assembly E, comprising the regulator 33 and the compensating accumulator 37, at reduced pressure PR is identical to that which has been described in connection with FIG. 1 and it is preferably connected to the pipe 19 by a pipe 39 opening into the upstream region 43 of the pipe 19.

It is also possible to provide a safety valve 51 connected to the portion of the hydraulic circuit 35 which is at the pressure PR. This safety valve is calibrated for a pressure slightly higher than PR and protects the assembly E against any abnormal overpressure, for example in the event of leakage of the non-return valve 41.

It is well known that, in hydraulic control circuits for circuit breakers, the final supply / purge valves of the jack or jacks, which are large sections, are not directly controlled (as has been shown for simplification in the figures 1 and 2) but via several pilot valves and relay valves of increasing sections.

These pilot valves and relay valves form part of the hydraulic circuit for sending orders and at least some of the chambers which they comprise are also subjected to circulations of emulsified oil or empty volumes of oil. As in the case of the pipes described in connection with FIGS. 1 and 2, there occurs, during the tripping operation, shortages of oil or appearances of emulsified oil in some of the parts of these relay valves or pilot valves and in the pipes on which they communicate, which affects the speed of response at the time of re-pressure.

It is therefore advantageous to replenish oil at reduced pressure at least some of the chambers of these valves.

FIG. 3 shows the essential elements of a conventional oleopneumatic control, similar to that represented in FIG. 1 in that the connecting pipe 19-19 ¹ , between the operational block 21 and the purge supply valve 7 of the cylinder 1, is only a channel for sending orders ("under pressure" or "unpressurized"). The high-speed supply to the jack 1 is provided by the main accumulator 5. As a variant, a purge supply valve 7 is shown, a conventional valve comprising an independent supply valve 53 and a purge valve 55, l the hydraulic actuator 15 of the valve being constituted by the piston-shaped portion of the purge valve 55.

An auxiliary high-pressure accumulator 5 ′ is also shown supplying the operational block 21, these two accumulators being connected in pressure equilibrium by a low-flow line 56 (shown in broken lines in FIG. 3) and being recharged conventionally by a pump not shown.

Such a control system conventionally comprises relay valves, of which only one has been shown under the reference 57.

It suffices to recall that this relay valve has a high pressure inlet 59, a high pressure outlet 61 connected to the connection pipe 19 ′, a purge outlet 63 and a control input 65 connected to the connection pipe 19 with the block. operational 21. The supply 66 and purge 66 ′ valves of the valve 57 are controlled by a pilot cylinder 67.

The assembly E comprising the regulator 33 and the compensating accumulator at reduced pressure 37 is connected, by a pipe 39, to the chamber purge 69 of the relay valve 57. On a tripping order of the solenoid valve 25, the supply / purge valve of the operational block 21 comes into the purge position 27 shown in solid lines; the pilot cylinder 67 no longer being under pressure, the purge valve 66 'opens and purges the chambers 69-69' and the pipe 19 '. The decompression and the circulation of the oil in these volumes produces the phenomena of lack of oil and of emulsion which have been indicated previously. The assembly-E replenishes immediately and directly, in oil at the pressure PR, the chambers of the relay valve and the pipe 19 ′, thus ensuring a normal response time to the next engagement order.

A check valve 47 ′ (similar to the valve 47 in FIGS. 1 and 2), calibrated for a pressure greater than PR, is provided on the purge line 39 ′ connected to the line 39 connecting the assembly E and the chamber of the relay valve 57.

As can be seen in FIG. 3, the chamber 69 is never subjected to high pressure, since, in the engaged position, the valve 66 ′ is closed and isolates the chamber 69. This is why, in this embodiment, there is no provision for a non-return valve on the pipe 39 similar to the non-return valve 41 in FIGS. 1 and 2.

This has the advantage that the compensated accumulator at reduced pressure 37 is not only recharged by the regulator 33 but also partially recharged by the purge oil originating from the decompression of the pipe 19 'at each tripping operation.

Of course if there are one or more other relay valves, for example in the operational block 21 in place of the simple supply / purge valve 27-27 'which has been schematically represented, the chambers of these relay valves equivalent to the chamber 69 can also be replenished with oil at pressure PR by another compensating assembly E or from the assembly E shown in FIG. 3.

It should be noted that the compensator assembly E according to the invention is also operating during long periods of immobilization in the triggered position during which any possible return of air is prevented by the supply of oil at reduced pressure PR from the compensator assembly E. It is thus ensured that, from the first engagement maneuver, the response times will be respected.

FIG. 4 shows an embodiment of the compensating accumulator 37 at reduced pressure PR and at low capacity. The accumulator comprises a variable volume oil storage chamber 71 which is closed by a waterproof membrane 73 urged by a spring 75, with the interposition of a support plate 77. A connector 81 opening into the chamber 71 is connected to the connection pipe 39 (Figures 1, 2, 3). A vent valve 83 is also provided for the air purge on first filling. Such an accumulator has a low inertia, the total stroke of the membrane 73 being for example 5 to 10 mm for a membrane surface of 20 to 40 square centimeters, or a capacity of approximately 10 to 40 cubic centimeters. Thanks to this low inertia, the compensation of empty oil volumes, or filled with emulsified oil, is very fast.

Claims (8)

1. Oleopneumatic control for electric circuit breaker which comprises: a jack (1) for actuating the movable contact (3) of the circuit breaker: a main high pressure oleopneumatic accumulator (5): a supply / bleed valve system (7) of the jack, selectively connecting the working chamber 9 ′ of the jack to the accumulator or to a low pressure enclosure (11); return means (13-13 ′) of the jack in the tripped position of the circuit breaker: a hydraulic order sending circuit comprising at least: a hydraulic actuator (15) sensitive to the pressure which, when subjected to the high pressure, brings said valve system to the supply position, and, when it is no longer subjected to the high pressure, brings it to the purge position; an operational block (21) for sending orders; a link circuit (19) between the operating unit and said valve system .; and a regulator (33), connected to the hydraulic order sending circuit, said regulator delivering a reduced pressure PR. from the high pressure of the accumulator (5), said control being characterized in that it comprises at least one compensator accumulator at reduced pressure (37), of low capacity compared to that of the main accumulator recharged at said pressure PR by said regulator and connected by a line (39) to said hydraulic circuit for sending orders (15, 19, 21). 2. Control according to claim 1, characterized in that the capacity of the compensating accumulator (37) is of the order of 100 to 1000 times lower than that of the main accumulator (5). 3. Control according to one of claims 1 or 2, characterized in that, on the connection pipe (39) connecting the compensating accumulator (37) to the hydraulic circuit for sending orders (15, 19, 21) is interposed a non-return valve (41) allowing only the flow of oil from the compensating accumulator to the order sending circuit. 4. Control according to one of claims 1 to 3, characterized in that a check valve (47, 47 ') calibrated for a pressure slightly greater than the reduced pressure PR is interposed on the purge circuit (19, 45 , 39, 39 ') of the order. 5. Control according to one of claims 1 to 4, characterized in that the connection pipe (39), connecting the compensating accumulator (37) to the hydraulic circuit for sending orders (15, 19, 21), ends, on this circuit, in the vicinity of its upstream end (43), by considering the direction of circulation of the oil in said circuit when said circuit passes from the "pressurized" situation to the "non-pressurized" situation. 6. Control according to any one of the preceding claims, characterized in that the order sending circuit (15, 19, 21) also constitutes the oil supply circuit under high pressure of the jack (1). 7. Oleopneumatic control according to one of claims 1, 2 or 4, characterized in that it comprises at least one hydraulic relay valve (57), interposed, in the order sending circuit, and in that the compensator accumulator (37) is not only connected to the regulator (33) to be recharged by the latter, but also to a chamber (69) of at least one of said hydraulic relay valves (57) said chamber receiving the purge oil from the sending line order (19 ') when the latter is put "pressureless". 8. Control according to any one of claims 1 to 7, characterized in that the reduced pressure compensating accumulator PR (37) is a low inertia accumulator comprising a membrane (73) which delimits the oil chamber (71) and which is biased by a mechanical spring (75) acting on the membrane by means of a support plate (77).

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