Drive System

As noted above, we had one major crash caused by the new building drive. The main concern (and surprise) was that one of the motors could fail without the system detecting it and actually continuing trying to turn the building. No specific mention of this could be found in the very extensive documentation. This error was already detected earlier during tests and to avoid the building continuing to move hardware signals to TCS were installed for each of the 4 motors so if any of them failed the TCS would take immediate action by fast stopping the building drive and the telescope azimuth drive to avoid a building crash between them and above all to avoid grinding flat surfaces on the drive wheels. At this time also a system was set-up to diagnose the problem and instructions were provided for resetting the system after such an event. This system was in place during the reported error and an analysis pointed to the communication with the motor which was already suspected, and as a result the encoder cable to the motor was replaced.

A computer is being purchased to provide a dedicated building drive error display that can also be remotely accessed, thereby giving full remote access to the building drives in case of problems or for test purposes.