TB/T 3027 is the Chinese railway industry standard that specifies the technical requirements for computer based interlocking at railway stations. It is not primarily an electromagnetic compatibility standard, and it is included here because interlocking equipment is a case in which electromagnetic requirements and functional safety requirements meet: the system must remain safe when it fails, so any disturbance that could change a route setting, release a route or permit a movement that has not been authorised is a safety hazard rather than a performance problem. The standard therefore sets out the functional and safety requirements of the interlocking, including the principles by which routes are established and locked, the handling of failures, the redundant architecture and the means by which the system is proven, and it imposes requirements on the environment in which the equipment operates, among them the electromagnetic conditions and the power supply arrangements at a station. It is applied together with the industry standards covering the electromagnetic protection of signalling installations.