If the Master key is not off, what might happen when troubleshooting defective pantos?

When the Master key is not off during troubleshooting, it allows the defective pantographs (pantos) to potentially continue operating, even if they are not functioning correctly. This situation can lead to unsafe conditions where the pantographs may provide power to the system or engage in movements that could pose hazards while repairs are being made.

The importance of ensuring the Master key is off is to prevent any unintentional operation of the pantos during fault diagnosis and repair processes. By having the key on, troubleshooting could fail to address the issues effectively, since the equipment is still responsive to commands, thereby complicating the identification of defects and the safety of personnel working on or around the pantographs. Proper procedures typically require that the Master key be disengaged to ensure complete control over the pantos and verify that all systems are disabled before maintenance begins.