Drawout type switchgear

Abstract: The sliding mechanism (50) of a drawout type switchgear has a first slide arm (5) which is slidably supported by the upper and lower support rails (3A, 3B) and a second slide arm (7) which is slidably supported by the first slide arm (5). The second slide arm (7) is interlocked with the first slide arm (5) by a lock plate (12) when the first slide arm (5) is sliding from a connected position to a final drawout position of the first slide arm (5). When the first slide arm (5) reaches the final drawout position of the first slide arm (5), the interlocked second slide arm (7) is released by rotation of the lock plate (12).

Description: The present invention relates to a drawout type switchgear. More particularly, it concerns with such a drawout type switchgear which comprises a base frame, a pair of support rails mounted on both sides of the base frame, a slide frame slidably held by the support rails and a circuit breaker supported by the slide frame. An example of a drawout type switchgear is disclosed in the Japancse published examined utility model publication (Jikko) Sho 63-5384. In this known drawout type switchgear, if the circuit breaker is designed to have a long extension stroke or interval by means of a long slide frame, the drawout type switchgear can be easily maintained and an inspection at the drawout position of the circuit breaker which is fully removed from the base frame is readily possible. However, in order to achieve a small sized drawout type circuit breaker, the slide frame for drawing out the circuit breaker can not be designed to have a long extension interval. Consequently, it is difficult to conduct the maintenance and the inspection of the small sized drawout type circuit breaker because the circuit breaker can not be fully removed from the base frame. From US-A-2 865 685 a further example of a drawout type switchgear is known. This switchgear has a telescopic slide mechanism, so that in the full extended position of the slide mechanism the circuit breaker is fully removed from the base frame and thus readily accessible, but in the retracted position the slide mechanism has - due to its telescopic action - a short axial length permitting a small sized drawout type circuit breaker. For permitting a sliding movement of the telescopic slide mechanism prior to moving the circuit breaker out of its frame a button must be manually depressed in order to unlock the slide mechanism such that the circuit breaker can be moved. The present invention has been made in order to solve the above-mentioned problem. An object of the present invention is to provide a drawout type switchgear of which a maintenance and an inspection can be easily conducted in spite of small sized configuration. In order to achieve the above-mentioned object, the drawout type switchgear of the present invention comprises: a base frame; a circuit breaker, which is movably mounted on said base frame, and which is to be locked at plural positions, namely a connected position wherein the circuit breaker is entirely received within said base frame and the electrical circuits are in a connected state, a disconnected position wherein the circuit breaker is slid in a drawout direction from the connected position to a position where the electrical circuits are in a disconnected state and a drawout position where the circuit breaker is fully removed from said base frame; a pair of upper and lower support rails which are mounted on both side plates of said base frame; a first slide arm which is slidably supported by said upper and lower support rails; a second slide arm which is slidably supported by said first slide arm, and which is fixed to said circuit breaker; and lock members which automatically lock said second slide arm to said first slide arm when the circuit breaker is drawn out from said connected position to said disconnected position and then release said second slide arm such that the circuit breaker can be drawn further to said drawout position until said first slide arm reaches its final drawout position and lock said first slide arm to said base frame, said lock members release upon an forced overlapping movement between said second slide arm and said first slide arm. According to the above-mentioned drawout type switchgear of the present invention, a maintenance and an inspection are easily conducted in spite of the small sized configuration because the drawout type switchgear comprises a small sized slide frame having a long extension interval. Furthermore, the lock members automatically lock said second slide arm to said first slide arm when the circuit breaker is drawn out from said connected position to said disconnected position and then release said second slide arm such that the circuit breaker can be drawn further to said drawout position. Accordingly, a single person can easily draw out the circuit breaker without the necessity of operating a button or the like prior to draw-out. Further, in the drawout type switchgear of the present invention, the circuit breaker is locked at a disconnected position without fails, and is prohibited from projecting in a drawout direction owing to a shock or a shake. Therefore, the drawout type switchgear can realize a high reliability of the manufactured product. While the features of the invention are set forth particularly in the appended claims, the invention, both as to organization and content, will be better understood and appreciated, along with other objects and features thereof, from the following detailed description taken in conjunction with the drawings, in which: FIG. 1 is a perspective view of the drawout type switchgear of a first embodiment in accordance with the present invention in its drawout state; FIG.2 is a side view showing an inner face of a sliding mechanism of the drawout type switchgear of FIG.1; FIG.3 is a side view showing the main part of the sliding mechanism in a connected state before a circuit breaker is drawn out from a base frame of the drawout type switchgear of FIG.1; FIG.4 is a side view showing a lock member of the sliding mechanism of FIG.3; FIG.5 is an exploded perspective view showing the sliding mechanism of FIG.3; FIG.6 is a side view showing the main part of the sliding mechanism in an intermediate state of a drawing operation of the drawout type switchgear of FIG.1; FIG.7 is a side view showing the lock mechanism of the sliding mechanism of FIG.6; FIG.8 is a side view showing an inner face of a sliding mechanism of a drawout type switchgear of a second embodiment in accordance with the present invention; FIG.9 is a side view showing the sliding mechanism in an intermediate state of a drawing operation of the drawout type switchgear of FIG.8; FIG.10 is a side view showing the sliding mechanism in a connected state before a circuit breaker is drawn out from a base frame of the drawout type switchgear of FIG.8; FIG.11 is an exploded perspective view showing the sliding mechanism of FIG.10; FIG.12 is a perspective view showing a part of a sliding mechanism of a drawout type switchgear of a third embodiment in accordance with the present invention; FIG.13 is a perspective view showing a part of a sliding mechanism of a drawout type switchgear of a fourth embodiment in accordance with the present invention; FIG.14 is a side view showing a part of a lock lever unit of a drawout type switchgear of a fifth embodiment in accordance with the present invention; FIG.15 is a perspective view showing the lock lever unit of FIG.14; FIG.16 is an exploded perspective view showing the lock lever unit of FIG.15; FIG.17 is a side view showing an inner face of a sliding mechanism of FIG.14; FIG.18 is a side view showing an intermediate state of the sliding mechanism of FIG.17; and FIG.19 is a side view showing a disconnected state of the sliding mechanism of FIG.17. It will be recognized that some or all the Figures are schematic representations for purposes of illustration and do not necessarily depict the actual relative sizes or locations of the elements shown. In the following paragraphs, the present invention will be described in detail concerning the preferred embodiments shown in the attached drawings. A first embodiment of a drawout type switchgear in accordance with the present invention is described concerning the accompanying drawings of FIGs. 1 to 7. FIG.1 is a perspective view of the drawout type switchgear of the first embodiment in a drawout state wherein a circuit breaker 11 is drawn out from the base frame 1. FIG.2 is a side view showing an inner face of a sliding mechanism 50 of the drawout type switchgear. FIG.3 is a side view showing the sliding mechanism 50 in a connected state before a circuit breaker 11 is drawn out from a base frame 1. FIG.4 is a side view showing a lock plate 12 in the sliding mechanism 50 of FIG.3. FIG.5 is an exploded perspective view showing the sliding mechanism 50 of FIG.3. FIG.6 is a side view showing the sliding mechanism 50 in an intermediate state of a drawing-out operation. FIG.7 is a side view showing the lock plate 12 of the sliding mechanism 50 of FIG.6. As shown in FIG.1, the base frame 1 of the drawout type switchgear slidably receives the circuit breaker 11 supported by the sliding mechanism 50. The circuit breaker 11 can be drawn out from or pushed into the base frame 1 by an operation of a drawout/push-in unit 51 to which a detachable handle (not shown) is connected when the circuit breaker 11 is drawn out or pushed into the base frame 1. The drawout type switchgear has a locking unit (not shown) which can lock the circuit breaker 11 at three positions, namely a "connected position", a "disconnected position" and a "drawout position". (i) When the circuit breaker 11 is locked at the "connected position", the circuit breaker 11 is entirely received within the base frame 1, and both of a main circuit and a control circuit in the drawout type switchgear are in a connected state. (ii) When the circuit breaker 11 is locked at the "disconnected position", the circuit breaker 11 can be slid in a drawout direction from the connected position, and then, both of the main circuit and the control circuit are in a disconnected state. (iii) When the circuit breaker 11 is locked at the "drawout position", the circuit breaker 11 is fully removed from the base frame 1. In FIG.2, which shows the sliding mechanism 50, a pair of an upper support rail 3A and a lower support rail 3B are mounted on inner faces of both side plates 1a of the base frame 1 by means of screw bolts 4. Both side plates 1a are supported to each other by an angle bar 2 connecting them. A first slide arm 5, which is formed to have a first slot 6, is slidably supported by a pair of the upper support rail 3A and the lower support rail 3B as shown in FIGs. 2 and 3. A second slide arm 7 having a second slot 9 is disposed along the first slide arm 5, and is slidably supported by the first slide arm 5. A first support pin 8, which is provided at a rear portion (right side portion in FIG.2) of the second slide arm 7, is slidably engaged with the first slot 6 of the first slide arm 5. A second support pin 10, which is provided at a front portion (left side portion in FIG.2) of the first slide arm 5, is slidably engaged with the second slot 9 of the second slide arm 7. Therefore, the circuit breaker 11, which is fixed to the second slide arm 7, can be drawn out from or pushed into the base frame 1. The lock plate 12 is provided on an inner or a rear portion (right side portion in FIG.2) of the first slide arm 5 pivotaly about a pivot pin 13. The lock plate 12 has a hook 12a forwardly projecting and a projection 12b upwardly projecting. The lock plate 12 is urged by a lock spring 14 in a manner to be always biased in a counterclockwise direction about the pivot pin 13 as shown in FIG.5. Next, drawing-out operation of the above-mentioned drawout type switchgear of the first embodiment is described concerning FIGs. 2 to 7. In the connected state, where the circuit breaker 11 is inserted in the base frame 1 as shown in FIG.3, the hook 12a of the lock plate 12 is abutted to an upper face of the lower support rail 3B, and hence the projection 12b of the lock plate 12 is engaged with a recess 7a of the second slide arm 7. FIG.4 shows the lock plate 12 in the above-mentioned condition. As a result, the second slide arm 7 is interlocked with the first slide arm 5 in a manner to slide between the upper support rail 3A and the lower support rail 3B. Accordingly, when the circuit breaker 11 is moved from the connected position shown in FIG.3 to an intermediate position shown in FIG.6, the first slide arm 5 and the second slide arm 7 slide together. As shown in FIGs. 6 and 7, when the first slide arm 5 reaches an intermediate position in the drawing-out operation, that is at a final drawout position of the first slide arm 5, the hook 12a of the lock plate 12 has come off the front end (left ends of the drawings) of the lower support rail 3B; and then the lock plate 12, which is urged by the lock spring 14 in a counterclockwise, direction is rotated. As a result, the projection 12b of the lock plate 12 comes off the recess 7a of the second slide arm 7. Only the first slide arm 5 at this intermediate position is inhibited from further drawing out by the known stopper unit. When the circuit breaker 11 is further drawn out from the above-mentioned intermediate position, the second slide arm 7 supporting the circuit breaker 11 only slides so as to remove from the base frame 1 as shown in FIG.2. In this drawing-out operation, that is during the while the second slide arm 7 is only sliding, the first support pin 8 mounted on the second slide arm 7 travels in the first slot 6 of the first slide arm 5, and simultaneously the second support pin 10 of the first slide arm 5 travels in the second slot 9 of the second slide arm 7. Consequently, the sliding mechanism 50 is fully extended, and the circuit breaker 11 is fully removed from the base frame 1 as shown in FIGs. 1 and 2. In the above-mentioned drawing-out operation for the circuit breaker 11, the second slide arm 7 is moved along the first slide arm 5 after the first slide arm 5 was slid between the upper support rail 3A and the lower support rail 3B. Accordingly, the circuit breaker 11 is steadily and reliably removed from the base frame 1 by the sliding mechanism 50 comprising the first slide arm 5 and the second slide arm 7. And, the drawout type switchgear comprising this sliding mechanism 50 has an improved workability in the maintenance operation and so on, and can realize a stabilization in the drawing-out operation. In the following paragraphs, a push-in operation of the above-mentioned drawout type switchgear is described. In the first step of the push-in operation, the first slide arm 5 shown in FIG.2 is inhibited from sliding in a backward direction (rightward in FIG.2) by an abuttment between the hook 12a of the lock plate 12 and the front end of the lower support rail 3B. Therefore, when the circuit breaker 11 is pushed into the base frame 1 in the above-mentioned first step of the push-in operation, only the second slide arm 7 is moved in the backward direction. When the second slide arm 7 reaches the intermediate position shown in FIG.6, the second slide arm 7 abuts the projection 12b of the lock plate 12. And the second slide arm 7 makes to pivot the lock plate 12 in the clockwise direction against the force of the lock spring 14. FIG.7 shows the lock plate 12 just before the second slide arm 7 is abutted to the projection 12b. As a result, the hook 12a of the lock plate 12 comes off of the front end of the lower support rail 3B, and the projection 12b of the lock plate 12 is engaged with the recess 7a of the second slide arm 7. Consequently, the first slide arm 5 and the second slide arm 7 are interlocked therebetween, and are pushed into the base frame 1, thereby to become into the connected state as shown in FIG.3 and FIG.4. And the circuit breaker 11 is locked at the connected position by the locking unit. A second embodiment of a drawout type switchgear in accordance with the present invention is described with reference to the accompanying drawings of FIGs. 8 to 11. Corresponding parts and components to the first embodiment are shown by the same numerals and marks, and the description thereon made in the first embodiment similarly apply. Differences and features of this second embodiment from the first embodiment are as follows. FIG.8 is a side view showing an inner face of the sliding mechanism 60 having the first sliding arm 5 and the second sliding arm 7 of a drawout type switchgear of the second embodiment. FIG.9 is a side view showing the sliding mechanism 60 at the intermediate state in the drawout/push-in operation. FIG.10 is a side view showing the sliding mechanism 60 in the connected state before the circuit breaker 11 is drawn out from the base frame 1. FIG.11 is an exploded perspective view showing the sliding mechanism 60 shown in FIG.10. As shown in FIGs. 8 to 11, the sliding mechanism 60 of the drawout type switchgear comprises a first support roller 16, which is rotatably supported by a first bracket metal 15, and a second support roller 18, which is rotatably supported by a second bracket metal 17. The first support roller 16 is provided at an upper rear portion of the first sliding arm 5 so as to contact to a lower face of an upper support rail 3A. The second support roller 18 is provided at a lower front portion of the side plate la of the base frame 1, and is disposed at a lower position adjacent to the front end of the lower support rail 3B so as to contact to the lower face of the first slide arm 5. In the second embodiment, the first slide arm 5 is slidably supported by the first support roller 16 and the second support roller 18, as well as a pair of the upper support rail 3A and lower support rail 3B. Consequently, when the first slide arm 5 is sliding from the connected position shown in FIG.10 to the intermediate position shown in FIG.9 between a pair of upper and lower support rails 3A and 3B, the operational load in the drawout/push-in operation is received by rotation of the first support roller 16 and the second support roller 18. As a result, the drawout type switchgear of the second embodiment can realize a reduction of the operational load in the drawout and push-in operation of the circuit breaker 11, and has an improved workability. A third embodiment of a drawout type switchgear of the present invention is described referring to the accompanying drawing of FIG.12. Corresponding parts and components to the first embodiment are shown by the same numerals and marks, and the description thereon made in the first embodiment similarly apply. Differences and features of this third embodiment from the first embodiment are as follows. FIG.12 is a perspective view showing the way of supporting the upper support rail 3A and the lower support rail 3B of a sliding mechanism 70 in the drawout type switchgear of the third embodiment. As shown in FIG.12, the lower support rail 3B is supported on and by the upper edge of the angle bar 2, which is firmly connected between the lower portions of the both side plates 1a of the base frame 1. The upper support rail 3A is supported by a bent plate 19 which resists to a lifting force owing to the moving of the first slide arm 5 supporting the circuit breaker 11. The bent plate 19 is formed by bending a cut portion of the side plate la of the base frame 1. As a result, the upper support rail 3A and the lower support rail 3B in the third embodiment have respective strengthened support constructions, which is free from error of rail positions. Therefore the drawout type switchgear of the third embodiment realizes the high reliability of the manufactured product. A fourth embodiment of a drawout type switchgear of the present invention is described referring to the accompanying drawing of FIG.13. Corresponding parts and components to the first embodiment are shown by the same numerals and marks, and the description thereon made in the first embodiment similarly apply. Differences and features of this fourth embodiment from the first embodiment are as follows. FIG.13 is a partly perspective view showing the first slide arm 5 and the second slide arm 7 of a sliding mechanism 80 in the drawout type switchgear of the fourth embodiment. As shown in FIG.13, the first slot 6 of the first slide arm 5 is formed to have a large notch 20 extended downward therefrom; and the second slot 9 of the second slide arm 7 is formed to have a notch 21 extended downward therefrom. The large notch 20 is provided to receive a head of the first support pin 8 for assembling of the sliding mechanism 80. The notch 21 is provided similarly to receive a head of the second support pin 10 during assembling. As a result, in the assembling process of the sliding mechanism 80, the second slide arm 7 can be fitted with the first slide arm 5 after the first slide arm 5 was attached to a pair of the upper support rail or the lower support rail mounted on the base frame 1. Accordingly, the drawout type switchgear of the fourth embodiment has an improved workability in the assembling process. A fifth embodiment of a drawout type switchgear of the present invention is described referring to the accompanying drawing of FIGs. 14 to 19. Corresponding parts and components to the first embodiment are shown by the same numerals and marks, and the description thereon made in the first embodiment similarly apply. Differences and features of this fifth embodiment from the first embodiment are as follows. FIG.14 is a side view showing a part of the side plate la of the base frame 1 in the drawout type switchgear of fifth embodiment. FIG.15 is a perspective view showing a lock lever unit 160 provided on the second slide arm 7 of the drawout type switchgear of the fifth embodiment. FIG.16 is an exploded perspective view showing the lock lever unit 160 of FIG.15. In FIG.14, which shows the drawout type switchgear in the disconnected state, the side plate la of the base frame 1 is formed to have a cutoff part 15 at the front portion of the side plate la. The cutoff part 15 has at its back end part a projection 15a which is for engagement with an upper end of a lock lever 16. As shown in FIGs. 15 and 16, the lock lever 16, which comprises an arm portion 16a having a journal hole 16c and an end portion 16b, is mounted rotatably on an outer face of the second slide arm 7. The lock lever 16 is rotatably held by a support pin 17, which is fixed to the second slide arm 7 through the journal hole 16c of the lock lever 16. The end portion 16b of the lock lever 16 is engaged with an edge of a square hole 7b, which is configured in the second slide arm 7. The end portion 16b of the lock lever 16 is biased in a direction shown by an arrow 21 of FIG.15 by a spring 18 engaging across the support pin 17 and the end portion 16b. As shown in FIG.16, the support pin 17 has a head having a lateral through-hole 17c for receiving one end of the spring 18, a supporting portion 17a for rotatably journaling the lock lever 16 and a semicircular shaft 17b for fixing to a semicircular hole 7c of the second slide arm 7. A handle 19 is formed by bending the front end of the second slide arm 7 for manually drawing-out or pushing-in the base frame 1. Next, drawing-out operation of the above-mentioned drawout type switchgear of the fifth embodiment is described referring to FIGs. 14, 17, 18 and 19. FIG.17 is a side view showing an inner face of the sliding mechanism 90 in the connected state as same as the aforementioned state shown in FIG.4. FIG.18 is a side view showing the sliding mechanism 90 in the intermediate state, and FIG.19 is a side view showing the disconnected state. In the connected state shown in FIG 17, that is the circuit breaker 11 is fully inserted to the base frame 1, the hook 12a of the lock plate 12 is abutted to the upper face of the lower support rail 3B. Therefore, the projection 12b of the lock plate 12 is engaged with the recess 7a of the second slide arm 7. As a result, the first slide arm 5 and the second slide arm 7 are interlocked to be slid together, similarly to the interlocking mechanism in the aforementioned first embodiment. When the circuit breaker 11 is drawn out from the connected position (FIG.17), the first slide arm 5 and the second slide arm 7 slides out of the base frame 1 to be supported by the upper support rail 3A and the lower support rail 3B. When the circuit breaker 11 in the base frame 1 reaches the disconnected position shown in FIG.14, the lock lever 16, which is biased by the spring 18 in a direction indicated by an arrow 21 of FIG.14, is engaged with the projection 15a of the side plate la. In this disconnected state, though the circuit breaker 11 can be returned to be inserted to the base frame 1, the circuit breaker 11 is prevented from being drawn out in a drawout direction indicated by an arrow 20 of FIG.14 because the lock lever 16 can not be turned in a direction indicated by an arrow 22 of FIG.14. Consequently, it is prevented that the circuit breaker 11 in the disconnected state projects from the base frame 1 in the direction indicated by the arrow 20 owing to an unexpected force of a shock, vibrations and the like. When the circuit breaker 11 is drawn out of the base frame 1 in order to conduct a maintenance, an inspection and so on, the operator makes the lock lever 16 to rotate in the direction indicated by the arrow 22 (FIG.14) overcoming the pressure of the spring 18. As a result, the lock lever 16 is disengaged from the projection 15a of the side plate la. Therefore, the first slide arm 5 and the second slide arm 7 can be drawn out from the base frame 1 together with the circuit breaker 11. After the above-mentioned state, that is the circuit breaker 11 is drawn out from the disconnected position, when the first slide arm 5 reaches the intermediate position shown in FIG.18, the hook 12a of the lock plate 12 comes out of the front end of the lower support rail 3B, and the lock plate 12 rotates around the pivot pin 13 by the force of the lock spring 14 similarly to the aforementioned first embodiment. At the same time, the projection 12b of the lock plate 12 does not engage with the recess 7a of the second slide arm 7. The first slide arm 5 is inhibited from drawing out further from the intermediate position by a known stopper unit (not shown). As a result, only the second slide arm 7 can be slid along the first slide arm 5 by the sliding means of the first support pin 8 and the second support pin 10 which travel in the first slot 6 and the second slot 9, respectively. Consequently, the circuit breaker 11 is fully removed from the base frame 1 as the same drawout state shown in FIG.19 as the aforementioned first embodiment shown in FIG.1. In the following paragraphs, a pushing-in operation for inserting the circuit breaker 11 to the base frame 1 of the drawout type switchgear in the drawn-out state shown in FIG.19 is described. In the pushing-in operation, the first slide arm 5 is inhibited from moving in a backward direction (rightward in FIG.19) by abutting between the hook 12a of the lock plate 12 and the front end of the lower support rail 3B as shown in FIG.19. Therefore, when the circuit breaker 11 is pushed into the base frame 1, the second slide arm 7 is moved only in the backward direction. When the second slide arm 7 reaches the intermediate position shown in FIG.18, the second slide arm 7 abuts the lock plate 12. The second slide arm 7 makes the lock plate 12 to rotate around the pivot pin 13 in the clockwise direction against the force of the lock spring 14. As a result, the hook 12a of the lock plate 12 disengages from the front end of the lower support rail 3B; and the second slide arm 7 and the first slide arm 5 are slid in so as to be received by the base frame 1. In the pushing-in operation, the top end 16t of the lock lever 16 is pushed down by a front curved periphery of the projection 15a, and the lock lever 16 is rotated overcoming the force of the spring 18 in the direction indicated by the arrow 22 of FIG.14 because the top end of the lock lever 16 moves along the front curved periphery of the projection 15a. The top end 16t of the lock lever 16 overrides the projection 15a and thereby finally is caught by the projection 15a as shown in FIG.14. FIG.14 shows the disconnecting state of the drawout type switchgear. As shown in FIG.14, the lock lever 16 in the fifth embodiment is designed to arrange behind the handle 19 of the second slide arm 7. Therefore, when the circuit breaker 11 is to be drawn out from the base frame 1 by using the handle 19, the lock lever 16 can be operated to be released by pulling forward (rightward in FIG.14) by a finger of the operator during holding the handle 19. Accordingly, the release operation of the lock plate 16 and the drawout operation of the circuit breaker 11 are conducted by one motion by the operator. The drawout type switchgear of the fifth embodiment can realize an improved workability and a stabilization in the drawout operation. Apart from the above-mentioned fifth embodiment wherein the sliding mechanism comprises a double slide structure of the first slide arm 5 and the second slide arm 7, a modified embodiment may be such that the sliding mechanism comprises a known single slide structure. Although the present invention has been described in terms of the presently preferred embodiments, it is to be understood that such disclosure is not to be interpreted as limiting. Various alterations and modifications will no doubt become apparent to those skilled in the art after having read the above disclosure.

Claims: A drawout type switchgear comprising: a base frame (1); a circuit breaker (11), which is movably mounted on said base frame (1), and which is to be locked at plural positions, namely a connected position wherein the circuit breaker (11) is entirely received within said base frame (1) and the electrical circuits are in a connected state, a disconnected position wherein the circuit breaker (11) is slid in a drawout direction from the connected position to a position where the electrical circuits are in a disconnected state and a drawout position where the circuit breaker (11) is fully removed from said base frame (1); a pair of upper (3A) and lower (3B) support rails which are mounted on both side plates (la) of said base frame (1); a first slide arm (5) which is slidably supported by said upper and lower support rails (3A, 3B); a second slide arm (7) which is slidably supported by said first slide arm (5), and which is fixed to said circuit breaker (11); and lock members (7a, 12, 14) which automatically lock said second slide arm (7) to said first slide arm (5) when the circuit breaker (11) is drawn out from said connected position to said disconnected position and then release said second slide arm (7) such that the circuit breaker (11) can be drawn further to said drawout position until said first slide arm (5) reaches its final drawout position and lock said first slide arm (5) to said base frame (1), said lock members (7a, 12, 14) release upon an forced overlapping movement between said second slide arm (7) and said first slide arm (5). The drawout type switchgear in accordance with claim 1, wherein said lock members (7a, 12, 14), comprise a lock plate (12) which is rotatably provided to said first slide arm (5), and having a hook (12a) and a projection (12b), and, when said hook (12a) slides to abut to a face of a support rail by a lock spring (14), said projection (12b) engages with said second slide arm (7) to interlock said first slide arm (5) and said second slide arm (7), and further, when said hook (12a) comes out from said face of said support rail at said final drawout position of said first slide arm (5), said hook (12a) is rotated by said lock spring (14) to engage with said support rail but said projection (12b) disengages from said second slide arm (7). The drawout type switchgear in accordance with claim 1 or 2, wherein a first support roller (16) to contact to a lower face of said upper support rail (3A) is provided at a back portion of said first slide arm (5) and a second support roller (18) to contact to a lower face of said first slide arm (5) is provided at a front position of said side plate (1a) of said base frame (1) close to a front end of said lower support rail (3B). The drawout type switchgear in accordance with anyone of claims 1 to 3, wherein said lower support rail (3B) is supported by and on an angle bar (2) which connects between both side plates (1a) of said base frame (1), and said upper support rail (3A) is supported by a cut and bent plate (19) which is formed by bending a cut portion of said side plates (1a). The drawout type switchgear in accordance with anyone of claims 1 to 4, wherein said first slide arm (5) has a first slot (6) for permitting therein traveling of a first support pin (8) which supports said second slide arm (7), said second slide arm (7) has a second slot (9) for permitting therein traveling of a second support pin (10) which is mounted on said first slide arm (5), and said first slot (6) has a notch (20) for inserting a head of said first support pin (8) and said second slot (9) has a notch (21) for inserting a head of said second support pin (10). The drawout type switchgear in accordance with anyone of claims 1 to 5, wherein a lever lock unit (16) is provided on said second slide arm (7) to rotate in a lock release direction only, and which is engaged with said side plate (1a), thereby to prevent said circuit breaker (11) from coming further out of said base frame (1) when said circuit breaker (11) is disposed at said disconnecting position.

Inventors: ISHIKAWA TAKAYOSHI, ISHIKAWA, TAKAYOSHI, Ishikawa, Takayoshi, c/o Mitsubishi Denki K.K.
Applicants: MITSUBISHI ELECTRIC CORP, MITSUBISHI DENKI KABUSHIKI KAISHA
Application year: 1992
Main classification: H05K7
IPC codes: H02B11, H05K7