How long can an operator wait before pumps shut off during pantograph flushing?

The correct answer is 10 seconds, which reflects the standard maximum wait time for an operator during pantograph flushing before the pumps automatically shut off. This time frame is crucial for ensuring that the flushing process is effective while also preventing potential damage to the system from prolonged fluid flow.

In the context of pantograph flushing, it is essential to balance efficiency with safety. A 10-second window allows enough time for an operator to assess the flushing process and determine if adjustments are necessary without risking overload or damage to the pumps or the system.

The other options, while depicting various times, do not align with the established protocol for pump operation during this specific procedure. Energetically, longer wait times could indicate an ineffective flushing operation or a risk of system failure, while shorter intervals may not provide sufficient opportunity for assessment. Hence, 10 seconds is set as the optimal duration for operator intervention in this scenario.