The problem: traction inverter drives and signalling compatibility

For the safe operation of the railway it is essential that any traction vehicles running on it, in conjunction with the power supply system do not interfere with the correct operation of the signalling system. Here, the authors consider how this problem is approached by the signalling engineer and how this may lead to a specification for permissible interference such that the signalling equipment would continue to operate safely. They also consider how this in turn presents a problem to traction designers and how the specification has developed in the light of such experience