So in the year 2020, you will write an obituary for the WAP-4 Class Electric Loco on IRI.
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WAP-1to4 Class Non-3Phase Electric Indian Locos... RIP (1980-2020)
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These locos started their earlier runs with...
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trains like the Howrah Rajdhani. Their progressive manufacturing lead IR to phasing out the WAM-4 locos in 1997. Now these locos with their last variants of the P-4 model with the arrival of latest 3-Phase technology electric locos named WAP-7. IR is also planning a WAP-7D variant to haul trains at 140-160 Kmph on 9 specific routes. May the traditional electric locos be remembered by IRI for their immense contribution on Indian tracks under perverse Indian conditions _/\_

Sir,
As per Vision 2020 it is Seen. Here some points are to be noted:
If you kindly have a look at /blog/post/1440076(Vide News Entry# 221976) about the Subject:
" Indian Railways in 'severe financial crisis' again, finds panel headed by ex-Rail minister Dinesh Trivedi"
You...
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Can find that the Report which is Shared here by this Panel tells the following
1 Indian Railways have a huge drainage of Money for the Depreciation of it's Over Aged Assets and in maximum cases Depreciation is under estimated.
2 IR have a increased Per Unit Cost in both Passenger and Freight Sector which resulting in a "Negetive Operating Ratio" in both Freight and Passenger Sector
Operating Ratio= Operating Expense/Net Sales
In both Sectors Sales/Revenue figure is much less than Operating Expense.
Most importantly, IR can't generate enough Cash Flows from it's Passenger & Freight Operations that can be utilised for Procuring New Rakes, Wagons & Locomotives on the other hand drainage of money for maintaining these Over Aged Assets.
The Panel also comments that the "Financial Position of IR" is now not Sufficient enough to carry on it's Operation as a "Going Concern".
So, as per my Rail Fanning Experience I can say
1 3 Phasers will have less maintenance cost than Tap Changers
2 As per Current CLW situation Tender For Tap Changers are now becoming impossible due to availability of material.
3 IR can save both Power and Money in three phaser for it's "Regenerative braking"
4 Though CLW 3 Phaser cost 13 Crore(WAP 7 & WAP 5)[7 Crore more than Tap Changer WAP-4] but the aftermath costs of 3 Phasers are Less as compared to Tap Changers.
5 Not now, but after some years IR has to say "Good Bye" to it's Tap Changer" Fleets and have to use 3 Phaser for it's numerous Monetary and other benefits.
Thanks & Regards
Nilanjan Ray