On the basis of Electrical Power drive:
(i) Non Electrical Traction
(ii) Electrical Traction
Non Electrical Traction: Traction system which does not uses the electrical power to drive, are called Non Electrical Traction system.
there are various types of non electrical systems:
- Steam Engine
- Diesel Engine
Electrical Traction: Traction system which uses the electrical power to drive, are called Electrical Traction system.
there are 4 types of electrical systems:
- D.C. System
- Single Phase A.C. System
- Three Phase A.C. System
- Composite System
- D.C. system: D.C. system contains D.C. supply of rating 600V, 750V, 1500V, 3000V.
dc system uses the low voltage ,series wound D.C. Series Motor to drive the train. dc motor is well suited to railroad traction, being simple to construct and easy to control. Until the late 20th century it was universally employed in traction system.
- Single Phase A.C. System: Alternating current system was used due to incapability of dc system i.e. high voltage. The higher voltage limit for the dc system was 3000 Volts. With alternating current, especially with relatively high voltage over-head wire, fewer substations are required, and the lighter overhead current supply wire that can be used correspondingly reduces the weight of structure needed to support it to the further benefit of capital cost of electrification.
single phase 16 *(2/3) Hz and 25 Hz frequency of supply is used in single phase ac system .
A.C. series motor is used due to high starting torque. Substations are used in distance of 30-40 Km to maintain the voltage level along the track. Voltage rating is 15-25 KV for this system.
- Three Phase A.C. System: This system is used for high voltage ratings. In three phase system we can transmit high voltage level which is for efficient transmission is required.
This system uses 3 phase induction motor, 3 phase supply, 50-60 Hz supply.
voltage rating of motor is 3.3-3.5 KV.
- Composite System: There are two types of composite systems.
- single phase to dc system
- single phase to 3 phase system
The first one single phase to dc system is used where voltage level is high for transmission and dc machine is used in the locomotive.
single phase to 3 phase system is used where 3 phase machine is used in the locomotive and single phase track we have.