Aim : Draw sketch of current collecting equipments

Theory :

Current collecting systems

there are mainly 2 systems for locomotive tramsways or trolley buses viz .1.conducter rail systems .2.overhead current collection systems.overhead current collection systems is superior than conductor rail systems this is because both theoratically and experimentally current collection is more difficult from rigid body than from an elastic body farther than elevation would also the be impracticable and endanger the safety of personnel.

Conducter rail system

this is employed at 600 volt for suburban service on account of its relative cheapness and easier inspections and maintenance .the supporting structure does not necessary to protect the rail from accident also it is not necessary to protect.in case of time one rail conducter the advantages of using insulated return current on other public service buried in the vicinity of railway tunnels the rails are mounted on insulators parallel with track rails at a distanc of 3 to 0.4m from the running rails with their most surface acting at constant surface and are fed at suitable points from sub stations.

the rails are designed from electrical consideration are .1.electrical conductivity.2.cost.3.wearing qualities.4.contact.surface available for conducter rail keeping i view the type of insulator used.a special steel alloy is used for rails it provieds high conductivity and at same time satiesfies all other requirement.

Overhead current collection system

this system is adopted when trains are to be supplied at high voltage.in this systemwith high operating voltage the train requiring high power may be current supplied through conducter ofrespecting small cross section and collection of current required by train can be done by a collector with a sliding contact over head is universal for all ac railways and is also used with dc tramways trolley buses and locomotives.in alll these cases

the running rails are utilised at return conducter therefore width ac single phase systems.only one overhead wire is required for each track

1.trolley collecter

it is universally employed with tramways and trolley buses.this consists of grooved gun metal wheel or grooved slides shore with carbon insert carried at the end of long pole .

the other end of this pole is hinged to a swivelling base fixed to roof of vehicle necessary upward pressure for the pole and current collecter is provided for each wire the bases being mounted side by side the pressure for the pole and current collecter is provided for each wire the bases being mounted side by side .the pressure for wheel is approx 10 kg and for a carbon inside slider is approxinately17 kg and for a carbon insert drawback of trolley collecter is that it has to be rotated through 180.for reversing the direction of motion of vehicle

2.bow collector

it is also employed for current collection with tram ways.the bow collector consists of light metal strip 0.6 to 0.9 metre wide pressing aginst trolley wire and attached to frame work mounted on the roof of vehicle.althuogh provision work mounted on roof of vehicle to rrun at higher speed work without running the riskof leveling the contact of trolley wire is lost it is as such not suitable for trolley wire at high speed .it is desire that wire being accurately located above track rail and stay about 15 cm to each of the wearing of groove in contact strip collection strip is made of soft material such as copper alluminium or carbon so that it should work out collection strip than trolley wire necessary upward pressure is obtained by springs

3. Pantograph collector

the pantograph collector is employed in railways for collection of current where the operating speed is high at 100 or 130 kmph and the currents to be collected are at on the roof large at 2000 to 3000 amps pantograph are mounted on the roof vehicle and usually of steel tubing .the coinside of jointed frame usually trolley wire .these consists of shoes are usually about 1.2 meter long there may be single shoe straight throughout

their lenths or camberred slighted or may be in the form of an quirally bow material plates of copper and slightly or may be in the form an auxirally bow material used for pantograph is often steel with sometimes varying paltes of copper or bronze instead of preesure varies from 5 to 10 kgs.

the pantograph is raised or lowerd from the drives cubby one of the following methods or with some modification of it .

the above arrange ment has the following advantages over bow type collector

 It can operate in either direction of motion  Ther is no risk overhead network is very simple due to absence of points and grooved crossing required for bows.

Its height can be varied from drivers cabin by carrying out simple operations .

Conclusion : in this practicle we conclude that the various current collecting system line conductor rail system overhead system and also study that different current collector like trolley collector bow collector and pantograph collector. pantograph collector is mostly used in electric traction system.