Air insulated switching stations contain electrically connected protecting and measuring devices as well as HV switching apparatus. Typically, the said devices are arranged in lines, separately for each individual phase, forming separate current ducts for each individual phase. In a multi-phase air-insulated switching station individual current ducts are arranged parallel to each other and they are connected to the corresponding HV overhead lines. Electrical apparatus, namely disconnectors, circuit breakers, current and voltage transformers, and surge arresters are present within individual current ducts in various configurations and at various levels with respect to the ground. Such switching station design provides appropriate spacial requirements for individual devices as well as for groups of devices.

There are also known air-insulated switching stations in which individual devices are combined into a single piece of equipment. An example of such solution is the device presented in the patent application PCT 97/26692, describing a HV switch assembly composed of a disconnector integrated with a circuit breaker and instrumentation transformers.

In the device described both the circuit breaker and the disconnector are mounted on one and the same stand with one single support base. The stand also carries a current meter and earthing means. The central supporting insulator carries a two-element circuit breaker disposed in a T-shaped mount. Each of the breaker elements carries on its outer end a respective disconnector of a pantograph kind.

Combining functions of different devices in a single device reduces space required.

Since in each 3-phase switching station there are at least three parallel current ducts, the integration described is significant from both economical and practical point of view.

In the case of the 3-phase switching station however, separate switching units has to be installed for each individual current duct.

The object of the invention is an integrated unit for an air-insulated high voltage switching station containing a HV disconnector having transverse arms whose free ends are equipped with main contacts and for which the vertical insulators are attached to a frame forming a base, characterised in that the disconnector member is equipped with a rotary column attached to the base which said rotary column is affixed to three insulators forming the transversal arms arranged so that their projection on the surface perpendicular to the rotation axis of the column forms an image of medians of equilateral triangle crossing the pivoting point of the column.

The three vertical insulators are connected to the base so that they are parallel to the pivoting axis of the column arranged symmetrically to each other and to the rotation axis of the column.

Each of the vertical insulators is equipped with main contacts attached to the free ends of the insulators. Each of the main contacts is electrically connected to the corresponding head which in turn is connected to the input cables supplying HV current to the main contacts.

Each of the heads is in the best way electrically connected to one end of the surge arrester attached parallel to the corresponding vertical insulators. The surge arresters are located preferably inside the insulators. The surge arresters have their opposite ends grounded. Output cables are electrically connected to the main contacts located on the corresponding transversal arms of the disconnector.

In the second embodiment of the device according to the invention each of the main contacts is electrically connected to the head which is electrically connected to the input cables supplying HV current to the main contacts. Output cables are attached to the respective transversal arms of the disconnector and

each of the output cables is connected to the corresponding main contacts located at free ends of the transversal arms. All individual output cables have a common output path located along the rotary column preferably inside the column.

In this embodiment of the device each of the heads is electrically connected to one end of the surge arrester, attached parallel to the corresponding vertical insulators. The surge arresters are located preferably inside the insulators. The surge arresters have their opposite ends grounded.

Additionally, there are voltage and current measuring devices attached to each of the heads.

In the preferred embodiment of the device, there are circuit breakers located within the corresponding transversal arms of the disconnector.

In the another embodiment of the device according to the invention each of the circuit breakers is located on the extension of each corresponding vertical insulator, above the head. The upper end of the circuit breaker is equipped with a connecting head, connected to the corresponding input cable.

In the another embodiment of the device each of the circuit breakers is located below the head, whereas the connecting head with the corresponding input cable is located at the lower end of the circuit breaker.

The advantage of the device according to the invention is its design allowing for a significant space reduction with respect to the solution with three independent current ducts in the three-phase switching station. This is achieved by integrating three independent current ducts with a single, three-phase disconnector. Additionally, such a solution brings about a significant reduction of electrical connections among individual devices, existing in the conventional design of the switching station.

The object of the invention is schematically shown in the accompanying axionometric drawings in which: Fig. 1 illustrates the device in its simplest embodiment, being a disconnector; Fig. 2 is the device with the combined surge arresters; Fig. 3 illustrates the device with the common output path for all three output cables; Fig. 4 shows the device with the common output path for all three output cables and with the surge arresters ;

Fig. 5 illustrates the device with the common output path for all three output cables, with surge arresters, and additionally with circuit breakers; Fig. 6 illustrates the second embodiment of the device with circuit breakers ; Fig. 7 is the third embodiment of the device with circuit breakers.

As shown in Fig. 1, the rotary column 2 attached to the base 1 which said rotary column 2 is affixed to three symmetrically located insulators forming the transversal arms 3 of the disconnector. Free ends of the arms 3 are equipped with the main contacts 4.

Three vertical insulators 5 are connected to the base 1 so that they are parallel to the pivoting axis of the column 2 arranged symmetrically to each other and to the rotation axis of the column 2. The free ends of the insulators 5 are connected to the heads 6. equipped with main contacts 8 and HV terminals 7. The HV terminal 7 is located in the upper section of the head 6. Each of the heads 6 is electrically connected to the corresponding input cable 9 whereas output cables 10 are connected to the corresponding main contacts 4 located at the arms 3.

Fig. 2 illustrates the device shown in Fig. 1, in which the main contact 8 is electrically connected with the use of the head 6, to one end of the surge arrester 11 located inside the vertical insulator 5. The opposite end of the surge arrester 11 is electrically connected to the ground, which is not shown in the figure. Each of the heads 6 is electrically connected to the corresponding input cable 9 through the current and voltage measuring device12.

Fig. 3 illustrates the device shown in Fig. 1, in which there is an output cable 10 connected to each of the main contacts 4 located at arms 3, and each of the output cables 10 is located inside the corresponding arm 3. All individual cables 10 have a common output path 13 located inside the column 2.

Additionally there are current and voltage measuring devices 12 attached to each of the heads 6.

Fig. 4 illustrates the device shown in Fig. 3, in which there is an output cable 10 connected to each of the main contacts 4 located at arms 3, and each of the output cables 10 is located inside the corresponding arm 3. All individual cables 10 have a common output path 13 located inside the column 2. In this embodiment of the device the main contact 8 is electrically connected to one end

of the surge arrester 11 with the use of the head 6. The surge arrester is located inside the vertical insulator 5. The opposite end of the surge arrester 11 is electrically connected to the ground, which is not shown in the figure. Each of the heads 6 is electrically connected to the corresponding input cable 9 through the current and voltage measuring device 12.

Fig. 5 illustrates the device shown in Fig. 4, within each of the transversal arms 3 there is a circuit breaker 14 forming a part of the arm 3. One end of the circuit breaker 14 is electrically connected to the main contact 4. The opposite end of the circuit breaker 14 is connected to the output cable 10 and all individual output cables 10 have the common output path 13.

Fig. 6 illustrates a second embodiment of the device shown in Fig. 4, in which each of the circuit breakers 14 is located coaxially with respect to the corresponding vertical insulator 5. The surge arresters 11 are located inside the vertical insulators 5.-Each of the circuit breakers is located at the extension of the vertical insulator 5 and its lower end is connected to the head 6 which is electrically connected to the surge arrester 11. The current and voltage measuring device 12 is located between the head 6 and the lower end of the circuit breaker 14. Upper end of each of the circuit breaker 14 is connected to the connecting head 15 to which a corresponding input cable is attached.

Fig. 7 illustrates the third embodiment of the device shown in Fig. 4, in which each of the circuit breakers 14 is located coaxially with respect to the corresponding vertical insulator 5. The surge arresters 11 are located inside the vertical insulators 5. In this embodiment the head 6 with the corresponding main contact 8 is connected to the upper end of the corresponding circuit breaker 14.

Lower end of each of the circuit breakers 14 is connected to the connecting head 15 being in the electrical contact with the corresponding input cable 9. The connecting head 15 is in this embodiment also connected to one end of the surge arrester 11. The opposite end of the surge arrester 11 is electrically connected to the ground, which is not shown in the figure.

The operating principle of the device according to the invention is as follows: In the operating state ("on"state) the position of the rotary column 2 is so that there is a direct contact of each main contact 4 with the corresponding main contacts 8. Such position of the column 2 is achieved with the use of the drive

located below the base 1 which is not shown in the figures. Rotating the column 2 by 60 degrees results in rotating the three transversal arms 3 in the plane perpendicular to the rotation axis. This results in simultaneous disconnecting main contacts 4 from the main contacts 8 for all three phases, which provides visible discontinuities in the current ducts for all three phases, which is the"off"state of the device. The operating principle is identical for all the embodiments illustrated in figures 1,2,3, and 4.

The operating principle of the embodiments of the device illustrated in figures 5,6, and 7 is as follows: In the operating state ("on"state) the position of the rotary column 2 is so that there is a direct contact of each main contact 4 of the arm 3 with the corresponding main contacts 8 of the heads 6. At the same time the circuit breakers are in the"on"position. The current duct for each phase is thus continuous and there is current flow from the input cables 9 to the output cables 10. The values of current and voltage for each phase are determined with the use of the current and voltage measuring devices 12. The surge arresters 11 provide surge protection for each phase.

In order to brake the current ducts, at the first instance the circuit breakers are turned into the"off"state. This is achieved with a driving mechanism not shown in the figures. At the next step the column 2 is rotated by 60 degrees results in rotating the three transversal arms 3 in the plane perpendicular to the rotation axis. This results in simultaneous disconnecting main contacts 4 from the main contacts 8 for all three phases, which provides visible discontinuities in the current ducts for all three phases which is the"off"state of the device.