Overhead Catenary System

Presented by, Vinod Karvande Nilesh Patil Abhimanyu Sasane Akash Baviskar Avinash Ambre

 INTRODUCTION  OVERHEAD WIRE  OVERHEAD CATENARY SYSTEM  CURRENT COLLECTION SYSTEM  AUTOMATIC WEIGHT TENSIONING SYSTEM  IDEAL CHARACTERISTICS OF OHE  ADVANTAGES OF OHE  CONCLUSION

INTRODUCTION 1) The first and foremost function in electric traction is to keep the traction unit fed with the energy that it needs. For this purpose broadly speaking, there are two systems of current collection. i) Third rail ii) Overhead wire 2) Current collection from over head wire is far superior to that from the third rail 3) This is because both theoretically and experimentally current collection is more difficult from rigid body than from elastic one.

THIRD RAIL SYSTEM • The system gives unsatisfactory current at high speed. • This system mainly used for high density suburban traffic. • Electric supply is collected from an insulated rail running parallel to the track at distance of .3 to 0.5 m from the running rail. • Suitable for heavy current collection for voltages up to 750 to 1200 volts.

OVERHEAD WIRE o Shaped to fit trolley clamps. o copper clad steel contact wire and a copper alloy contact wire are used. o Size 4/0 AWG: for 1000 feet weight = 642 lbs. resistance = 0507 ohm o Wire expands & contracts with temperature. o Weights keep tension constant, or frequent support mitigates sag. o Nominal wire height above rail 18 feet.

TYPES OF OVERHEAD CATENARY SYSTEM

1.Simple Catenary 2.Compound Catenary 3.Stitched Catenary 4.Modified Y Catenary

Simple Catenary system  Simple catenary system with higher size conductors, heavier tension

and a pre sag (of1/1000 of span) is reported to be adequate for speeds upto 350 kmph.

Compound Catenary system  Compound system for HSR was evolved in Japan for

first bullet train

Shinkansen in 1964.  This system has a second catenary wire, called the auxiliary catenary wire

between the main catenary wire and the contact wire. It is joined to the main catenary wire and the contact wire by means of droppers which helps to reduce variations.  However, the good current collection characteristics of this type of

installation are offset by the increased material requirements and significant higher installation effort.

Compound Catenary system

• Latest compound catenary systems in operation is Taiwan-shinkansen

• A y-stitch wire is used to designate a connecting element inserted between

the catenary wire and the contact wire.

• Sicat H1.0 was used for HSR 300km/h in operation between Cologne and Frankfurt. • German rail has developed Y-stitch catenary system for conventional lines also

AUTOMATIC WEIGHT TENSIONING SYSTEM • When conductor is stretched between two ends then sag is produced which is inversely proportional to tension by the conductor • The main requirement for traction unit is not only give the steady spark less current but also provide temperature and wind pressures to maintain it in standard horizontal level • It consist of pulley block. • Increase in tension reduces elasticity of OHE and makes it more uniform ,however this will increase lateral stresses which would involve extra expenses.

ADVANTAGES oSpark less current collection and stable dynamic OHE . oCrip is adjustable oFluctuation in the height are eliminated oConstant tension in conductor.

IDEAL CHARACTERISTIC OF OHE Height of contact wire Loss of contact and its duration Quality of current collection Resonance of traction conductor.

Push up of contact wire Pantograph pressure Temperature Wear of contact wire

CURRENT COLLECTION EQUPMENT 1.PANTOGRAPH 2.TROLLEY POLE

PANTOGRAPH • • • •

Accommodates high currents. Guided by the vehicle. Uses carbon strips for contact. Contact point moves across the carbon as the car proceeds. • At curves: OCS is positioned to the outside of the track center line. • At junctions: diverging wire crosses the straight or runs parallel.

TROLLEY POLE • Used on legacy and heritage streetcars. • Contact shoe is guided by the OCS. • Slants upward in the trailing direction; double-end car has two poles. • At curves: OCS is positioned to the inside of the track center line. • At junctions: diverging wire ends at a frog.

ADVANTAGES OF OHE • • • • • •

Lower construction cost and cable cost. Current collection is simple. Advantage of air for cooling and insulation of the line. Vulnerable to strong wind and severe weather. Negative visual impact. Easier maintenance/repair work.

CONCLUSION • One advantage of electrification is the lack of pollution from the locomotives themselves. • If we want efficient and reliable operation of traction, the overhead catenary construction should be withstand at all the condition.