GB/T 24338.5 is the part of the Chinese railway electromagnetic compatibility series that deals with fixed power supply installations and apparatus. It is adopted from the corresponding international document but is written from the perspective of the Chinese railway network, in which the traction supply arrangements and the signalling systems differ in some respects from those of Europe. The standard sets emission limits and immunity requirements for the equipment installed in traction substations and along the line: the transformers, switchgear, converters and auxiliary apparatus that supply the traction current. Two distinct concerns are addressed. The apparatus must not emit disturbance that interferes with the signalling and communication systems that share the railway corridor, and it must itself continue to operate when the railway environment produces disturbances from lightning, from switching operations and from the traction current itself. Test levels and assessment criteria are given for each environment.