What device is used to detect the frequency of the engineer's movements and initiate a penalty brake application?

The device used to detect the frequency of the engineer's movements and initiate a penalty brake application is the Alerter. The Alerter system serves as a safety mechanism, monitoring the engineer’s activity to ensure that they are attentive and responsive while operating the train. When the system detects a lack of movement or response, it issues alerts, and if the engineer does not respond, it will trigger a penalty brake application to safely bring the train to a halt.

The Alerter is crucial for maintaining safety standards and reducing the risk of accidents caused by operator fatigue or distraction. As part of the broader safety mechanisms in place, it works alongside other systems, but its specific function focuses on real-time monitoring of the engineer's engagement with the operation of the train.