Yes DJ stands for "DisJuncteour" or whatever it is in french.This term probably appears because our electric locos have European origins and inspite of the older design ABCB(Air Blast Circuit Breaker)having been replaced by a simpler and more rugged...

Yes DJ stands for "DisJuncteour" or whatever it is in french.This term probably appears because our electric locos have European origins and inspite of the older design ABCB(Air Blast Circuit Breaker)having been replaced by a simpler and more rugged VCB,the term continues to avoid confusion for drivers.
VCB has only one set of one mobile and one fixed contacts which are designed to interrupt short-circuit level currents easily.Another feature of the VCB is that it can go through repeated duty cycles without any problems.This is especially important in traction duty where the DJ must be closed and opened frequently.
In older design ABCB(which can still be found on the WCAM-1 locos)the circuit breaker opens in two stages.There is a primary contact and a secondary contact in series with each other.The primary contact has a ball and socket arrangement.They are kept in firm contact with each other by a spring.When the circuit-breaker needs to be opened compressed air is allowed into the primary contact chamber which serves two purposes-it pushes the moving ball contact away from the fixed socket contact and at the same time the compressed air also blows away the arc drawn between the contacts.As soon as these contacts seperate,the secondary contact opens.Once the secondary contact has opened,the primary contacts are allowed to close again.While closing the circuit-breaker,only the secondary contact needs to be closed without touching the primary contacts.
DS is used only in DC line working and it does not have load-break features--that is it can't interrupt load currents and must be opened only in off-load conditions.Load-break functions are handled internally in DC line by heavy contactors called LDC.The WCAM-1 has 4 such contactors and the WCAM-2 has 6 such contactors.

DJ is Disc Joint.It is also called as VCB. This is the terminology used under AC operating conditions.While in case of DC we have DS that is Disconnecting Switch. The basic difference between DS and DJ is that DS can be set manually but not DJ.The main ...

DJ is Disc Joint.It is also called as VCB. This is the terminology used under AC operating conditions.While in case of DC we have DS that is Disconnecting Switch. The basic difference between DS and DJ is that DS can be set manually but not DJ.The main contact is a fixed contact.The auxiliary contact is a controlled by the air pressure from the panto reservoir used to make and brake the circuit.Both the Main and Auxiliary contacts are placed in a vacuum housing to avoid the arc when the DJ is closed.

@ Ankit.. DJ stands for 'Disjoncteur'. It is the french word for 'Circuit Breaker'..

1.Isn't vacuum enough to quench the arc???
2.If the auxiliary contact is inside the vacuum chamber, where are the main contacts???
3.VCB stands for Vacuum Circuit Breaker, what does DJ stand for???

There are two contacts. The main and the auxiliary. The auxiliary is housed in a vacuum enclosure. It picks up and connects a split second before the main contact. This done to avoid arching at the main contact.