Slip control, Over voltage relay, Main overload relay, Earth Fault Relay, Low Pressure Governor, Brake Cylinder Cutoff Valve, Train parting alarms and No OHE volt relay
The Indian locomotive class WAP-4 is a class of 25 kVACelectric locomotives that was developed in 1993 by Chittaranjan Locomotive Works for Indian Railways. The model name stands for broad gauge (W), AC Current (A), Passenger traffic (P) engine, 4th generation (4). They entered service in late 1994. A total of 773 WAP-4 were built at CLW between 1993 and 2015, which made them the most numerous class of mainline electric passenger locomotive until the WAP-7. The locomotive was developed after its predecessor, the WAP-1, was found inadequate to haul the longer, heavier express trains (24-26 coaches) that were becoming the mainstay of the Indian Railways network.
The WAP-4 is one of the most successful locomotives of Indian Railways serving both passenger and freight trains for over 27 years. This class provided the basic design for other locomotives like the WAP-6 . Despite the introduction of more modern types of locomotives like WAP-7, a significant number are still in use, both in mainline duties. Production of this class was halted in December 2015 with locomotive number 25051 being the last unit to be rolled out of Chittaranjan Locomotive Works. As of October 2021, all locomotives except those lost in accidents still retain "operational status" on the mainline as WAP-4, with further examples having been converted back from WAP-6.
Recently as per directive received from Railway Board [RB] all the loco sheds holding WAP-4 type locomotive have started "Mu" [Multiple Unit] operations. This configuration of Mu WAP-4 locos are being used to haul medium tonnage faster freight trains across IR.
The different locomotive sheds of WAP4 are Arakkonam, Santragachi, Erode, MughalSarai, Howrah and Bhusaval.
