78
6.2.8 Busbar earthing switch
To earth the busbars, earthing switches are used, also of type EK6. Their operating mechanism is
identical to that of the branch earthing switches (see section 6.2.7). The conditions for panel to panel
interlocking of the busbar earthing switches are described in section 3.4.2.
6.2.9 Earthing and short-circuiting with earthing module
• Isolate the area to be earthed and secure it against reconnection;
• Carefully follow all safety regulations;
• Remove the withdrawable circuit-breaker part from the relative switchgear panel;
• Secure the shutter in front of the live contact pins by means of the padlock. Screw on the earthing
module 142 actuating bars 142.1 (figure 129) as follows:
- To the top position for opening of bottom shutter;
- To the bottom position for opening of top shutter;
• Further screw on the earthing module 142 insulating plate 142.5 with 3 removable bushings as
follows:
- Contact arms 142.2 in the bottom position for earthing of cable output feeder;
- Contact arms 142.2 in the top position for earthing of busbars;
• Insert the earthing module 142 into the test/disconnected position and then move it into the service
position with the hand crank 121 (for procedure - see sect. 6.2.1);
• Using a high voltage tester, check that contact pins 142.7 of the earthing module are definitely
offcircuit;
• Withdraw the earthing module back into the test/disconnected position (see sect. 6.2.1);
• Mount a complete short circuit link 142.8 on the earthing module 142. Connect one end of earthing
cable 133.1 under one of three screws M12, with which short circuit link 142.8 is connected to contact
pins 142.7. Connect the second end of this cable to the earthing terminal 19.3 in the panel;
14.1
14.2
122
Fig. 127: Preparation for operation of branch earthing
switch - press the slide downwards.
14.1 Hexagonal shaft of earthing switch
operating mechanism
14.2 Slide
Fig. 128: Preparation for operation of branch earthing
switch - operating lever prepared for switch-
ing on/off
122 Operating lever
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