switch and the busbar connections in the DCC

• Vacuum again

• If required, clean using dry cloths

6.13 Checking the main and auxiliary contacts of the contactors, transfer switch and the busbar connections in the DCC

Visual checks must be carried-out at regular intervals to check wearing parts associated with electromechanical switching devices and identify the effects of ageing at busbar connections.

Carry-out the following for contactor K1, K2: • Remove the arc quenching chamber at contactor K1,K2

• Check the main contactor contacts for erosion; when required, replace the main contacts (for instructions, refer to instruction manual for contactors)

• Re-attach the arc quenching chamber

• Check the auxiliary contacts for visible traces of erosion, when required, replace

Carry-out the following for transfer switch Q1.1, Q1.2, Q1.3 and motor module Q1: • Check the main contacts of the switch modules for erosion, when required replace the switch modules (instructions on how to do this, refer to the chapter 7)

• Check the auxiliary contacts on motor module for visible traces of erosion, when required, replace

Visually check the complete power section; in doing so, place give special emphasis on the following points: • Are the cables damaged, is the insulation cracked or is there evidence of abrasion on the cables?

• Are components visibly damaged (phase modules, crowbar thyristor module, transducers)?

• Are the components and current-carrying parts discolored?

• Can white, crystalline traces be seen (these signify that the cooling system has leaks)?

• Are all of the cable lugs OK (none of the leads split, not discolored)?

• Is the busbar OK (visual check: Straight; no discoloring; no bubbling; not de-laminated)?

If there is evidence of problems or defects then they must be resolved.

Siemens Ltd. A5E01511750J/ 4M-2601-1645240 AC Shovel 295HD/ HR DCC Operation & Maintenance Manual 87