When carrying out maintenance in traction vehicles where high voltage is available, it is a mandatory duty to ensure the highest security level to the maintenance personal. Even today where any device can be remotely monitored and where sophisticated supervision tools are used to control the operating position of these devices, the most reliable way to guarantee the highest safety remains the use of a range of safety devices that can be mutually mechanically key interlocked. From the roof mounted pantograph to the high voltage containers inside the vehicle, the safety philosophy is based on a simple step by step principle that enables the manipulation of a safety device only once the previous one in the traction chain has been operated and locked in the grounding position.
