THYRISTOR CHOPPER CONTROL AND THE INTRODUCTION OF HARMONIC CURRENT INTO TRACK CIRCUITS

Alternating currents will generally be present in a d.c. traction supply owing to the action of synchronously switched power-control equipment and also to the presence of mains-frequency-harmonic voltage ripple. This paper describes the factors that determine the magnitude and frequency of such current in the power rails, for various conditions of d.c-chopper operation. Models that describe the introduction of harmonic current into track circuits are developed from power-circuit considerations, and theoretical predictions are compared with practical results obtained from measurements undertaken by London Transport. The use of multiphase chopper equipments to reduce the size of the input filter is considered, and it is shown that, when normal-load unbalance conditions are considered, no advantage is gained by using more than two phases.

• Corporate Authors:

  Institution of Electrical Engineers

  Savoy Place
  London WC2R 0BL, NY  England  10016-5997
• Authors:
  • Lowe, T J
  • MELLITT, B
• Conference:
  • Institution of Electrical Engineers, Proceedings
• Publication Date: 1974-4

Media Info

• Pagination: p. 269-275
• Serial:
  • Volume: 121
  • Issue Number: 4

Subject/Index Terms

• TRT Terms: Chopper circuits; Interference; Mathematical models; Thyristors; Track circuits; Traffic signal control systems
• Identifier Terms: London Transport; London Underground
• Old TRIS Terms: Choppers; Signal systems; Thyristor control
• Subject Areas: Operations and Traffic Management; Railroads;

Filing Info

• Accession Number: 00083934
• Record Type: Publication
• Source Agency: British Railways
• Files: TRIS
• Created Date: Jul 2 1975 12:00AM