Safety - Section 20 9/11 OM2041 Page 20-16 SPECIAL PRECAUTIONS FOR WORKING ON AC DRIVE TRUCKS Engine Shutdown Procedure Before Welding or Performing Maintenance Before welding or repairing an AC drive truck, maintenance personnel should notify a Komatsu service representative. Only qualified personnel, specifically trained for servicing the AC drive system, should perform this service. Normal operation of the drive system at shutdown will leave the system safe to maintain. However, in the event of a system failure, performing the follow- ing procedure prior to any maintenance activities will ensure that no hazardous voltages are present in the AC drive system.
If it is necessary to perform welding or repair to the truck without the field engineer present, the following procedures must be followed to ensure that the truck is safe for maintenance personnel to work on and to reduce the chance for damage to equipment. 1. Before shutting down the engine, verify the sta- tus of all the drive system status lights on the status indicator panel. If any drive system warning messages are dis- played, DO NOT attempt to open any cabinets, disconnect any cables, or reach inside the retarder grid cabinet without a trained drive sys- tem technician present - even if engine is off.
Only qualified personnel, specifically trained for servicing the A-C drive system, must perform this service. Anytime the engine is running, do not open any of the cabinet doors or remove any covers. Do not use any of the power cables for hand holds or foot steps. Do not touch the retarding grid elements. 2. If there are no drive system warning messages, follow all of the instructions for “Safe Parking Procedures.” 3. After the engine has stopped, open the access panel at the left front side of the control cabinet. Verify that the green link voltage light is illumi- nated and the DC bus voltage gauge reads 0.0 V.
Notify qualified drive system maintenance personnel if the green link voltage light remains off longer than five minutes after engine shut- down. Before opening any cabinets, removing any covers, or touching a retarding grid element or power cable, the engine must be shut down and the green link voltage light must be illuminated. 4. Locate the alternator cutoff switch in the front access panel on the left side of the main control cabinet. Place the CUTOFF switch in the ON position. This will prevent the alternator from re- energizing and creating system voltage until the switch is returned to the previous position. 5. Ensure both battery disconnect switches are in the OFF position.
Verify that the battery discon- nects are functioning. 6. Leave the drive system in the rest mode until the truck is to be moved.