Regular maintenance helps
Unit Removal & Replacement

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Make sure that the power switch in the unit is in the ‘OFF’ position before withdrawal. Refer to the scheme diagram and terminal chart before de-energising the control circuits. The initial movement from ‘Connected’ to ‘Test’ position is accomplished by turning the racking screw anti-clockwise. The screw disengages from the racking nut (mounted on the tray) approx. 3 turns after the ‘Test’ position. Thereafter the unit can be pulled out to ‘Disconnected’ and ‘Maintenance’ positions. In the ‘Maintenance’ position, the unit is completely out of the panel, yet mechanically attached to it. A spring-loaded pin prevents the unit from sliding accidentally into ‘Test’ position. For inserting the unit back to ‘Test’ or ‘Connected’ position, this pin has to be simultaneously pressed in with the unit. In the ‘Maintenance’ position, the unit can be tilted over to gain access to the contacts behind the unit as well as to the equipment mounted on the rear of the base plate. ONLY TWO COUNTER-SUNK SCREWS NEED TO BE REMOVED TO TILT THE UNIT. To remove the unit from the panel, withdraw it to the ‘Maintenance’ position and remove the four counter-sunk screws fixing the unit to be telescopic rails. Lift the unit and place it on a table/the floor. Push the telescoping part of the two rails inside to close the door. The unit will rest on the telescopic rail studs even when all the four counter-sunk screws are removed. As far as possible, keep the unit free from dst. Special care must be taken to protect the power and control contacts. Reverse the process for unit replacement.

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 Larsen & Toubro - Electrical Business Group