FI59512B - ANORDINATION OF THE PROCESSING OF MEASURES - Google Patents

Description

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Sweden-Sweden (SE) 7 ^ 11103-0 (71) ASEA Aktiebolag, S-721 83 Västeräs, Sweden-Sweden (SE) (72) Svante Johansson, Ludvika, Erik Strömblad, Ludvika, Sweden-6verige (SE) (7) * 0 Berggren Oy Ab (5I +) Device for earthing in switchgear cabinets - Anordning för Arbets-jordning i ställverkskip)

In order to protect personnel in electrical equipment inspection work, e.g. stipulates that the various phase conductors must be earthed and short-circuited at the workplace (so-called site earthing). For this purpose, different screw clamps are usually used, which are attached to different phase conductors and short-circuited and connected to ground potential via a flexible cable. To provide reliable grounding with these clamps, tightening is required at a certain torque, which means that the effectiveness of the precaution depends to a large extent on the person performing the work. Another disadvantage of using these clamps is that their installation is relatively time consuming, which naturally increases the risk of not grounding carefully enough. In addition, the switchgear enclosed in the cabinet has the disadvantage of the method described above from the point of view of personal safety that earthing cannot be carried out behind the doors of the closed cabinet.

It is further known (DT publication 1 19ä ä78) to use a manually inserted elongate earthing trolley equipped with a voltage test probe in high voltage switchgear. However, even with this 2 59512 device, earthing cannot be performed behind a closed cabinet door.

The object of the present invention is to provide a device for work earthing which is easier to connect than the above-mentioned earthing clamps and which at the same time ensures that earthing can be carried out with greater personal safety. This is achieved by a device in the form of an earthing truck having the features set out in claim 1. With such a forklift, earthing can be performed behind a closed cabinet door, and the pre-sensing phase of the forklift automatically provides a warning signal if the cabinet rail system accidentally becomes live when the earthing is started.

The connection between the signaling contact element of the truck and the alarm device is preferably made via a voltage transformer with two secondary windings, one supplying an audible signaling element and the other a light signaling element. In this case, a voltage warning is obtained, even if a fault occurs in the other signaling system.

The invention will now be described in more detail with reference to the accompanying drawing, which shows an embodiment of a grounding truck according to the invention. Figure 1 shows a side view of the truck, while Figures 2 and 3 show it from the front and from the rear.

The grounding truck shown in the drawing comprises a frame 2 movable by four wheels, which is intended to be pushed inside the switchgear cabinet when the grounding of the cabinet phase rails is to be performed. The frame 2 supports three contact members 3a, 3b and 3c arranged at a certain height from the floor, the mutual distance of which corresponds to the distance of the phase rails in the switch cabinet. The three contact members are connected to each other via a short-circuit rail 4 and connected via a ground conductor> to a sliding contact 6 which, when the truck is pushed into the cabinet, makes contact with a grounded slide rail fitted to the cabinet. The contact member 3b in the middle stage is arranged further backwards in the inward direction than the other two contact devices 3a and 3c. In front of this contact member 3b, a marking contact member 7 is arranged, which is mounted on an insulating holder 8, which is movable by a rod 9 against the action of a spring 10. The rear part of the signaling element 7 is made so that

Claims (8)

3 59512 that in the fully retracted position (earthing position) of the truck it makes good electrical contact with the contact device 3b. The signaling contact device 7 is connected to the earth conductor 5 via the primary winding of the voltage transformer 11. The voltage transformer 11 is provided with two secondary windings, one connected to the audible signaling element 12 and the other to the light signaling element 13. The drive is connected to the truck by means of a pin 14 projecting upwards from the top of the truck, and is otherwise adapted, via a hinge system 15, to act on a locking device 16 to lock the truck in the ground position. From below, the truck is provided with a foot-operated closing member comprising a latch 18 actuated by a spring 17 and adapted to co-operate with the lower edge of the switch cabinet door to lock the truck in the middle position. When grounding of the switch cabinet is started, the truck is first pushed into the cabinet so deep that the pin 14 engages the actuator mounted on the front of the cabinet, after which the cabinet door is closed. By means of the drive device, the truck is moved back to said central position, where it is mechanically locked by the closing member 18. In this position, the signaling contact member 7 makes contact with the middle phase rail of the switch cabinet and grounds the voltage transformer 11. If the cabinet rail system is live, both an audible and visual signal are obtained via the signaling elements 12 and 13. If no signal is received, the closing member 18 is released and the control to the connected position can be completed, whereby the rail system is grounded and short-circuited. Conventional earthing devices with cables can be connected if desired, after which the truck can be removed from the cabinet. A device for earthing in switchgear cabinets, comprising a grounding truck inserted into the switchgear cabinet, provided with contact members (3) adapted to contact the phase rails of the switchgear cabinet to short-circuit them with a grounding conductor (5) connected to the grounding truck and characterized in that the truck is equipped with a signaling contact valve (7) connected to the alarm device (12, 13), which is adapted to contact the second phase rail before the earthing truck is pushed into the cabinet before the rails are short-circuited; ) to a cabinet-mounted actuator for connection, which allows the truck to be moved to the ground position with the cabinet door closed. Device according to Claim 1, characterized in that the signaling contact element (7) is connected to the alarm device (12, 13) via a voltage transformer (11) fitted to the earth truck. Device according to Claim 1 or 2, characterized in that the signaling contact element (7) is arranged further in the insertion direction than the short-circuit contact device (3b) arranged in the same phase and is displaceable against the latter contact device (3b) against the action of a spring (10). Device according to Claim 1, 2 or 3, characterized in that the alarm device comprises both a light and an audible signaling element (13 and 12). Device according to claim 4, characterized in that the different signaling elements (12, 13) are supplied from their own secondary winding by said voltage transformer (11). Device according to one of the preceding claims, characterized in that the truck is provided with a mechanical closing element (17, 18) which is adapted to lock the truck in the middle position when the truck is pushed into the cab, where the truck signaling element (7) makes contact with the cab rail system. while the truck short-circuit contact means (3a, 3b, 3c) are spaced from the rail system. 1. For the purpose of arranging the use of the equipment and the use of the equipment in contact with the equipment, (3) the contact details of the equipment are used to contact the equipment in the case of the equipment (see)