Dear Arnab,
Reference:/blog/post/1575758
As per the Communication made by CLW through it's "Bi Monthly Corporate Communication Newsletter" CLW most probably stop the WAP-4 production within the Next Month or latest by Dec this year as because if you see the Tenders of CLW Website(Active CPP Tenders) you won't find any Conventional Loco related tender now. All are 3-Phase Tenders, moreover now they float tenders regarding the upgradation of the Civil Engineering Assests of Loco Production unit, it's sure that these Civil Engineering Assests upgradation is exclusively meant for 100% switchover to 3-Phasers....
more... Already they have stopped WAG-7 production(Last WAG-7 shell turned out from CLW in August 2015 which you find in the Photo Gallery of CLW's Official Website).
So upgradation is going at War footing manner for the 100% switchover to 3-Phasers in CLW and the Transition will likely occur either in Nov or in Dec 2015 which is inevitable.
Secondly, South Eastern won't be a hindrance for CLW as because it is depending on the Zone what it will do if SER is comfortable with WAP-4 then they can use WAP-4 only no harm in it. It's the mindset.
On the other hand, see southern Zone Royapuram is decorated with more and more WAP-7 and in future it will be a WAP-7 shed mainly by trasferring all it's WAP-4s to other zones. It's mindset dear, Southern has a positive mindset towards the 3-Phase Technology whereas SER has a stubborn and orthodox mindset for the reason best known to them. This is the Zonal issue and not likely to hamper 3-Phase production by CLW which is an independent body controlled by the Railway Board of India.