Abstract:
Apparatus for phase switching in a pumping-up power station includes a phase switching device to switch over between pumping-up and generating. The phase switching device includes a pair of disconnecting switches for pumping-up and generating integrally accommodated in a sealed casing filled with sulphur hexa-fluoride (SF 6 ) gas and an actuating mechanism for actuating the disconnecting switches.

Description:
BACKGROUND OF THE INVENTION 
     1. Field of the Invention 
     This invention relates to gas insulated switch-gear in a pumping-up power station, and, more particularly, to an apparatus for phase switching between the pumping-up and generating operations in a pumping-up power station. 
     2. Description of the Prior Art 
     The recently developed hydraulic power station is being gradually replaced by the pumping-up power station because of operation efficiency. The housing therefor is a tunnel structure of underground structure which does not impair the adjacent environment. As a result, a switch gear employing sealed sulphur hexa-fluoride (SF 6 ) has more restrictive sizing requirements. 
     On the other hand, the pumping-up power station needs apparatus for phase switching in order to permit the generator to function as a motor. 
     It is known that reversing the rotation of a three-phase motor is effected by reversing the connection of two of the three terminals. Accordingly, changing the generator from generator to motor is effected by reversing two switches. Two disconnecting switches, i.e. DS 1  of the generator and DS 2  of the motor, have been employed and phase-switched by alternative operation. 
     FIG. 1 shows a connecting diagram of the pumping-up power station. In FIG. 1, the generator G works as a pumping motor as described above. Tr designates a transformer, DS a main disconnecting switch, GCB a gas circuit breaker, DS 1  and DS 2  disconnecting switches for phase switching as described above, and BUS a bus bar. 
     A load (not shown) is connected to the bus bar BUS through a disconnecting switch DSa, a circuit breaker CB and a disconnecting switch DSb. 
     In such a structure, the disconnecting switch DS 2  of the motor side as described above is necessary to phase-switch the generator from a generating operation to a motoring operation and to then connect the bus bar to another power line to operate the generator G as a motor. If the disconnecting switches DS 1  and DS 2  are closed together, a shorting fault occurs. 
     Accordingly, the disconnecting switches DS 1  and DS 2  must satisfy the following conditions. When the disconnecting switch DS 1  of the generator side is closed, the disconnecting switch DS 2  of the motor side must be open and vice versa, and the disconnecting switches DS 1  and DS 2  can be opened together. 
     In order to satisfy such conditions, an interlocking mechanism as shown in FIG. 2 is provided between the disconnecting switches DS 1  and DS 2 . 
     A link LK with a clearance is provided between an actuating lever L 1  of the disconnecting switch DS 1  and an actuating lever L 2  of the disconnecting switch DS 2 . 
     One end barring the clearance of the link LK is engaged with the lever L 1  of the disconnecting switch DS 1 . Thus, the interlock mechanism IM comprises the link LK. In FIG. 2, like reference characters designate identical or corresponding parts as shown in FIG. 1. 
     However, since there is an interlocking mechanism, the structure of the arrangement and its adjustment are complicated. Further, since there are two disconnecting switches DS 1  and DS 2  separated from each other, the arrangement in general requires a great deal of space. 
     SUMMARY OF THE INVENTION 
     Accordingly, it is an object of this invention to provide a new and improved unique closed-up type switch gear which has a small size and a simple structure. 
     The foregoing and other objects are attained in accordance with one aspect of the present invention through the provision of an apparatus for phase switching between the pumping-up operation and the generating operation in a pumping-up power station, the apparatus comprising a sealed casing filled with an insulating gas, a pair of disconnecting switches which have a stationary contact and a movable contact and are integrally accomodated in the sealed casing, an actuating means for actuating the movable contacts so as to move reversely with respect to each other, and means for connecting the movable contacts. 
    
    
     BRIEF DESCRIPTION OF THE DRAWING 
     Various objects, features and attendant advantages of the present invention will be more fully appreciated as the same becomes better understood from the following detailed description of the present invention considered in connection with the accompanying figures of the drawing, in which: 
     FIG. 1 shows a single connecting diagram of a pumping-up power station, 
     FIG. 2 shows a front view, partly in a connecting diagram, of a prior arrangement, 
     FIG. 3 shows a front view, partly in a connecting diagram, of a preferred embodiment of the invention, 
     FIGS. 4 and 5 are schematic views showing an enlarged portion of the phase switching mechanism shown in FIG. 3, before and after the mechanism is operated, and 
     FIG. 6 illustrates a modification of the phase switching mechanism shown in FIG. 3. 
    
    
     DESCRIPTION OF THE PREFERRED EMBODIMENTS 
     Referring now to the drawing, wherein like reference characters designate identical or corresponding parts throughout the several views, and more particularly to FIG. 3 thereof, a phase switching device PHSD is mounted on a bus bar unit BUS and a gas circuit breaker GCB is mounted on a side portion of switching device PHSD. 
     A main disconnecting switch DS is mounted between an upper portion of the gas circuit breaker GCB and a connecting part TrC of a transformer Tr. 
     The bus bar BUS, the phase switching device PHSD, the main disconnecting switch DS and the connecting part TrC communicate with each other and are filled with an insulating gas such as SF 6  gas. 
     Three phase switching devices are provided at each three-phase terminal. For example, a first phase switching device exchanges the connections A and B of the bus bar BUS and a second phase switching device exchanges the connections B and A of the bus bar BUS to reversely connect the connection of the first phase switching device. A third phase switching device acts only as a disconnecting switch with respect to the connection C. Only the first phase switching device is explained. 
     FIG. 4 is a schematic view of an enlarged portion of the phase switching device PHSD shown in FIG. 3. In FIG. 4, a case 2 is mounted on top of a tank 1 for enclosing an operating mechanism as described hereinafter. Covers 3a and 3b are mounted to conducting members 5a and 5b through insulating members 4a and 4b. Opening-projecting portions are provided in the under portion of the tank 1 to facilitate mounting. 
     The conducting members 5a and 5b have a stationary contact fixed thereon which is coupled to the bus bars A and B shown in FIG. 3. An insulating spacer 7 having a connector 8 connected to the gas circuit breaker GCB is mounted on a side wall of the tank 1. A shaft 9 fixed on a pinion 10 of a rack and pinion mechanism is supported by the case 2 so as to rotate freely. A pair of movable racks 11a and 11b which are free to move up and down and which hold the pinion 10 therebetween are provided at both sides of the pinion 10 so as to move oppositely with respect to each other by rotating the pinion 10. 
     A pair of series bodies consisting integrally of insulating rods 12a and 12b and movable contacts 13a and 13b, to be engaged to the stationary contacts 6a and 6b, are respectively rigidly mounted on one side of the respective racks 11a and 11b. 
     Intermediate contactors 14a and 14b are electrically connected to the connector 8 and slidingly contact movable contacts 13a and 13b. 
     The stationary contact 6a and movable contact 13a constitute disconnecting switch DS 2 . The stationary contact 6b and the movable contact 13b constitute the disconnecting switch DS 1 . 
     The operation of the phase switching device PHSD shown in FIG. 4 and FIG. 5 will now be described. 
     FIG. 5 shows the phase switching device PHSD when the switching over as described hereinafter is completed, namely when the pumping-up is switched over. 
     In the phase switching device PHSD, usually, i.e. when the generator G is operated as a generator, the current flows from the connector 8, connected to one terminal of the gas circuit breaker GCB, to the bus bar B through the intermediate contactor 14b, the movable contact 13b, the stationary contact 6b and the conducting member 5b. 
     In the condition shown in FIG. 4, in the event that the phase switching device PHSD switches over after the gas circuit breaker is opened, the movable contact 13b is separated from the stationary contact 6b by the rising of the rack 11b when the pinion 10 is rotated counterclockwise by an actuator (not shown) coupled to the shaft 9 in accordance with the switchover command. 
     On the other hand, the pinion 10 causes the rack 11a to move down and both movable contacts 13a and 13b are separated from stationary contacts 6a and 6b when the movable contact is reached at an intermediate point of the stroke. 
     In this condition, if the operation of the rack and pinion mechanism is stopped, both disconnecting switches DS 1  (6b-13b) and DS 2  (6a-13a) assume the open state and the insulation between the stationary contact and the movable contact is maintained by the SF 6  gas. 
     Furthermore, if the pinion 10 is rotated counterclockwise by the actuator, the movable contact 13a for pumping-up (motor) approaches the stationary contact 6a and then is closed (FIG. 5). 
     In the event that the state shown in FIG. 4 is switched over to the state shown in FIG. 5, the phase switching device PHSD can be effected by clockwise rotation of the pinion 10 and can be switched over from pumping-up to generating. 
     FIG. 6 illustrates another embodiment of the phase switching mechanism shown in FIG. 3. 
     The embodiment described above is a combination of the pinion 10 and the racks 11a and 11b. However, the embodiment shown in FIG. 6 substitutes a link mechanism for the combination rack and pinion mechanism. The link mechanism comprises a lever 15 integrally fixed on the shaft 9 and links 16a and 16b which are free to rotate and which are respectively provided between the end portion of the lever 15 and the insulating rods 12a and 12b. 
     According to the invention as described above, since the phase switching device PHSD has a pair of stationary contacts and movable contacts for phase switching, which are accomodated in the same casing, it is possible to make the unit quite compact. The structure of the gas sealed switch gear can also be reduced. 
     Furthermore, as the movable contacts move reversely with respect to each other by the operation of the rack and pinion mechanism or the link mechanism, it is unnecessary to have a special interlock mechanism. It is therefore possible to simplify the mechanism of the phase switching device. 
     Obviously, numerous modifications and variations of the present invention are possible in light of the above teachings. It is therefore to be understood that within the scope of the appended claims the invention may be practiced otherwise than as specifically described herein.