Abstract:
A semaphore for use in a detection system for a high voltage device and for signalling a predetermined state of the device. The semaphore comprises a housing supporting therein a retroreflector element. The housing has an aperture and the retroreflector has a reflective surface supported in a alignment with the aperture. The housing is mounted in close proximity to the device. A linkage is associated with the housing and the device and is actuated upon the occurrence of a predetermined condition whereby to expose the reflective surface in the housing for the reflection of signals through the apertures. A remote scanning device continuously generates infrared signals in the direction of the aperture and detects reflective signals from the reflective surface.

Description:
BACKGROUND OF THE INVENTION 
     1. Field of the Invention 
     The present invention relates to a semaphore for use in a detection system and a method of detecting a predetermined state in a high voltage (HV) device, and wherein the predetermined state of the device, when sensed, activates a retroreflective device to reflect infrared signals continuously generated at the device and wherein the reflected signals are indicative that the HV device has reached a predetermined state. 
     2. Description of Prior Art 
     In our U.S. Pat. No. 4,451,910 there is described a signalling system which is associated with a high voltage device, herein a disconnect switch, whereby to signal the relative position of a moving contact in relation to a fixed contact. The system as disclosed therein is an ultrasonic system and which has proven extremely expensive to construct, and which may not be efficient during severe weather conditions, such as during a snowstorm, where the reflective surface of the mirrors in the receiver device may be obstructed by snow and ice, and render the receiver inaccurate. 
     The infrared detecting system of the present invention was conceived for use with a high voltage switch of the type disclosed in the referenced patent and having a fixed contact and a movable contact, and as utilized in an electrical distribution and transport network. However, the detecting system may have other applications with other high voltage devices such as for the monitoring of gas pressure in a high voltage device, or monitoring the level of oil in high voltage devices. 
     As described in our earlier U.S. Pat. No. 4,451,910, up to now the positions of the contact elements of high voltage disconnect switches have been ascertained by sensing the mechanism which displaces the moving contact blade which is used to close or open the switch. Microswitches are associated with the motorized mechanical connections of the moving contacts to generate signals identifying the position of the moving contact. However, such interconnecting drive mechanisms between the drive motor and the moving contact blade have many flexible connections and are sometimes inaccurate in the operation, and therefore could cause an inaccurate closure of the moving contact, although the microswitches would indicate that the contact is properly closed. Such errors could cause the destruction of the contacts when a strong current passes through the disconnect switch, and in certain cases it is necessary to make visual inspection of the disconnect switch to ascertain the position of its contacts. Therefore, presently known signalling systems are not totally reliable as to the information which they provide and prevent their use in a remote controlled system as often a visual inspection of the disconnect switch would be required. 
     SUMMARY OF INVENTION 
     It is a feature of the present invention to provide a detection system using a semaphore to signal a predetermined state of a high voltage device by reflecting infrared signals continuously generated in the direction of the retroreflector in the semaphore, and wherein the signals are reflected back by a retroreflector which is pivotally mounted in the semaphore housing. 
     Another feature of the present invention is to provide a method of detecting a predetermined state in a high voltage device by the use of an infrared detection system consisting of a semaphore having a retroreflector element therein which is pivotally mounted to reflect infrared signals continuously generated in the direction of the retroreflector in the semaphore upon the detection of a predetermined state of the high voltage device. 
     According to the above features, from a board aspect, the present invention provides a semaphore for use in a detection system for a high voltage (HV) device, and for signalling a predetermined state of the device. The semaphore comprises a housing supporting therein a retroreflector element. The housing has an aperture and the retroreflector has a reflective surface which is supported in alignment with the aperture. Means is provided for mounting the housing in close proximity to the device. A linkage is associated with the housing and the device and is actuated upon the occurrence of the predetermined condition whereby to expose the reflective surface in the housing for reflecting of signals through the aperture. A remote scanning device continuously generates infrared signals in the direction of the retroreflector, and also detects reflected signals from the reflective surface of the retroreflector. 
     According to a still further broad aspect of the present invention there is provided a method of detecting a predetermined state in a high voltage (HV) device. The method comprises the steps of supporting a retroreflective device in a housing having an aperture in alignment with the retroreflective device. The retroreflective device has a reflective surface and is pivotable to a reflecting and a nonreflecting position. A predetermined state of the high voltage device is sensed through a linkage means which is connected for pivotal displacement of the retroreflective device. Infrared signals are transmitted in the direction of the retroreflector, and a detector detects infrared signals which are reflected back by the reflective surface of the retroreflector when positioned to its reflecting position by the linkage upon the occurrence of the predetermined state of the HV device. 
    
    
     BRIEF DESCRIPTION OF DRAWINGS 
     A preferred embodiment of the present invention will now be described with reference to the accompanying drawings, in which: 
     FIG. 1 is a perspective view illustrating schematically the mounting of a disconnect switch utilizing the signalling system of the present invention; 
     FIG. 2 is a section view illustrating the construction of the semaphore; 
     FIG. 3 is a further perspective view illustrating a subassembly of the semaphore housing; and 
     FIG. 4 is a schematic illustration of a semaphore utilized in accordance with the present invention, but for detecting pressure change in a high voltage pressure switch. 
    
    
     DESCRIPTION OF PREFERRED EMBODIMENTS 
     Referring now to the drawings, and more particularly to FIG. 1, there is shown generally at 10 a high voltage disconnect switch which is usually connected to a transmission line of a three-phase electrical transmission system (not shown). The disconnect switch comprises essentially two metal support structures 11 and 12, each having a column of porcelain insulators 13 and 14, respectively. A further insulating column 15 of insulators is associated with the displaceable contact arm 16 of the disconnect switch and is rotatable by a drive motor 17 whereby to cause the blade contact 16 to axially rotate. Such a structure is well known in the art. 
     Referring additionally to FIG. 2, there is schematically illustrated the construction of the fixed contact 18 which receives the blade contact 16 to complete the circuit. The fixed contact comprises sets of opposed contact fingers such as 19 and 20 with contact finger 19 being spring-biased towards fixed contact 20. When the blade 16 enters between the two contact fingers 19 and 20, it is axially rotated by the drive 17 to assume the position as illustrated in FIG. 2, with the contact jaw being open and pressure being applied on the blade by the contact fingers 19 and 20. This assures good electrical conduction through the stationary contact. As previously described in our above-referenced U.S. patent, a cable 21 has a displaceable inner wire 22 connected to the movable contact finger 19 to transmit a mechanical signal of the position of the movable finger when fully engaged by the blade, as shown in FIG. 2. It is also implied that in some applications, inner wire 22 would be displaced by specially shaped &#34;dummy&#34; fingers installed in the proximity of the normal fingers. 
     When the movable contact blade is fully retracted, it assumes a position as shown in phantom lines at A. 
     As shown in FIG. 1, the detection and signalling system of the present invention consists in the provision of a semaphore 25 and 25&#39; associated respectively with the movable contact 16 and the stationary contact 18. A pair of infrared scanning devices 26 are each associated with their respective semaphores 25 and 25&#39;, and generate and detect a narrow beam of infrared signals at their respective semaphores and specifically at the aperture 33 thereof. These scanners 26 are well known in the art such as provided by Banner, Model SBLX-1, which is a special purpose retroreflective scanner for long range applications. 
     Referring now more specifically to FIGS. 2 and 3 there will be described the construction of the semaphore device 25&#39; associated with the fixed contact 18. It is pointed out that the other device 25 is of identical construction, but its cable 23 is operated by a linkage (not shown), which is actuated when the contact arm 16 reaches a fully open position A. The semaphore consists of a housing subassembly 27, housing a retroreflector element 28. A further housing subassembly 29 is provided with a rounded shape wall to prevent corona discharge from environmental high voltage circuits, and to prevent direct sunrays from saturating the receiver of the associated scanning device 26. The forward face 30 of the housing 29 is preferably of a non-reflecting finish. A tube 31 also forms part of the subassembly 27 and constitutes a housing for the retroreflector 28. The tube also forms the aperture 33 which receives the infrared signals and reflects them when the retroreflector 28 is in a reflective position, as shown in FIG. 2. A visor 32 is formed by an extension of the tube 31 protruding forwardly of the front face 30 to prevent accumulation of wind driven snow on the reflector. 
     As herein shown, the retroreflector is a corner-cube type reflector having a reflective surface 34 and mounted on a pivotal connection to which is secured a disc 35 located outside the cone 32 (see FIG. 3). The retroreflector disc 28 is displaceable to a nonreflective position, as shown in phantom as indicated by reference numeral 28&#39;, to a reflective position as shown in FIG. 2. This displacement is effected by a toggle linkage which comprises a pivotally mounted arm 36 having an intermediate pivot 37. The cable 22 from the movable contact finger 19 is secured at one end of the pivoted arm 36 through a suitable attachment part 38. The other end of the arm has a flexible connecting element constituted by a linkage spring 39, with the spring having an end 40 connected to the arm 36 and the other end 41 connected to the disc 35. The pivoted arm 36 is normally spring-biased in a downward direction, where the disc assumes its nonreflecting position as shown at 28&#39;, by a tension spring 42. 
     As can be seen in FIGS. 2 and 3, when the contact finger 19 is displaced outwardly to its position as shown in FIG. 2, the wire 22 will pull down on the connected end of the arm 36 causing the spring attachment end of the arm 36 to move upwardly. This applies tension in the linkage spring 39 and quickly rotates the disc 35 to its position as shown in FIG. 2, that is to say, the retroreflector snaps into its reflective position. Accordingly, infrared rays entering the tube through the aperture 33 and aligned on the mirror will be reflected back at the associated scanner 26&#39;, which detects the reflected rays indicating that the contact blade 16 has entered the jaw of the stationary contact 18, and has opened the jaws to assume a proper operation of the HV switch. In the specific application the infrared signals generated by the scanner were pulsated infrared signals, and they provide the advantage of preventing the scanner to be affected by ambient infrared rays that may come from the sun indirectly or from any other light source such as electric arcs. 
     Referring now to FIG. 4, there is shown another application of the semaphore of the present invention, and in this particular instance, for detection of the pressure level of a gas in a high voltage circuit breaker or a level of insulating oil in a transformer or bushing or any other variable that may be interesting to be monitored. As herein shown, the linkage would include a pressure gauge type device 50 having a connection 51 which disengages with a connection 52 associated with the retroreflector 53. If the pressure in the guage 50 falls or increases above predetermined limits, the connections 51 and 52 would disengage and cause the retroreflector 53 to assume a horizontal position by suitable spring-biasing means, not shown, to prevent reflecting the infrared rays 54 directed in the aperture 55 of the housing 56. 
     Many other applications of the detecting device of the present invention are conceivable and particularly for use with high voltage devices, i.e., where the voltage is in the range of 735 kV. Summarizing, the present invention provides a method and a system for detecting a predetermined state in a high voltage (HV) device by supporting a retroreflective device in a housing. The has an aperture in alignment with the retroreflector. The retroreflective device has a reflective surface which is pivotally mounted for displacement to a reflecting and a nonreflecting position. A predetermined state of the HV device is sensed by a linkage which is connected for pivotal displacement of the retroreflective device whereby, upon detection of the predetermined state, the reflective surface is positioned to reflect back infrared signals which are continuously transmitted at the aperture and retroreflector by a scanner device located remotely of the semaphore. 
     It is within the ambit of the present invention to cover any obvious modifications of the examples of the preferred embodiment described herein, provided such modifications fall within the scope of the appended claims.