I think CLW is at the Final stage of their Historic Transition likely to Occur Soon(Don't know the Time). Only 34 Active CPP Tenders have been floated most of which are relating to 3-Phase Loco and the up-gradation of Civil Engineering Assets of their Production Unit as per the Official Website of CLW.
Active Tender List of CLW:
click here
Hope and pray for...
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soon occurrence of this Long awaited Transition procrastinated unnecessarily for so many years.
Attached Image Link: click here

#TMProductionupdate
Production Achievement of CLW regarding the Following as on 24.10.2015:
1 HTM( Hitachi Traction Motor for WAP-4 & WAG-7 Conventional Loco)-------- 333 (Target for this year 500)
2 3-Phase Traction Motor 6FRA 6068(For WAP-7 & WAG-9/9H/9i Loco) ------- 551( Target for this year 943)
3...
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3-Phase Traction Motor 6FXA 7059(For WAP-5 Locomotive)-------------------- 08 (Target for this year 80)
4 SL-30(Smoothing Reactor of Locomotive)--------------------------------------- --- 51 (Target for this year 130)
5 SJ(Inductive Shunt of Locomotive)--------------------------------------- ----------- 147( Target for this year 195)
Please see the attached Screenshot for the Detailed Production Break Up.
Link:PRODUCTION ACHIEVMENTS AS ON 24.10.15

Exactly!
Addendum :-
The three phase system is also very stable and hence, widely used for practical applications. In this case, the instantaneous power is never zero. If you see the graph which you've posted, you can easily notice three sinusoidal waveforms generated by three different conductors, having a phase difference with respect to one another.
Example : Consider two highways - a one-lane...
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highway and a three-lane highway and you're driving a car. In the first case, if the vehicles stop moving you've to stop as well. In the second case, you still have two more lanes to keep moving if there's any disruption in the movement of vehicles in the first lane.
Hope that clarifies :)