Experimental investigation of influence of a.c. traction current on the rail circuits

The experimental investigation of spectral structure of return traction current was done on the section with a.c. traction. The 25 and 75 Hz harmonics determined among the rest coincide with the signal current in rails. The information about spectral structure of traction current can be used at the design of new systems, which are applied in the railway, and in other spheres.