WDM-2 Control Switches

by Apurva Bahadur, 1998.

Disclaimer: The information presented here is neither complete nor accurate. Complete details on the topics here are available only from Indian Railways and other official organizations. The material here is not a substitute for the official documentation or official training procedures, which are provided to duly authorized personnel. Do not use the information here to design, build, operate, repair, or maintain any equipment.

List of Electrical switches (some are circuit breakers) in the WDM2 18379 cab (of Pune shed).

Located on the Long hood bulkhead

  • CABL: Cab light breaker
  • ENGRL: Engine Room Light
  • DIL: Dome light switch (pronounced by a large number of drivers as 'Doom' light)
  • ERF: Emergency Radiator Fan switch (forces the radiator fan to run at the fastest speed in the event of engine overheating)
  • DSC: Not very clear - something required by the maintenance crew - the drivers do not touch it
  • B/A : Battery Ammeter (Center Zero with 200 Amps graduations in the + & - (charge & discharge directions, Ammeter for the 72 V engine battery.
  • B/A bypass: switch used to disconnect the field of the Battery charging generator: This causes the ammeter needle to deflect slightly in the negative direction (discharge). Normally the ammeter is at the zero position, i.e. the charge and discharge is evenly matched. The negative deflection is the proof that the battery is being positively charged in the normal position and that is why the needle is normally seen in the zero position.
  • ESD: Engine Start Lamp: Comes on when all the conditions are right for the engine to start
  • FPM: Fuel Pump Motor Breaker: Low pressure pump used to lift the diesel from the tanks to the injectors, always running when the loco is live
  • CCM: Crankcase Exhauster motor: Used to scavenge the potentially explosive and combustible vapour from the crank case. The discharge of the exhauster is at a bent pipe near the fuel tank. If the CCM is switched off, the oil leakage from the cylinder heads show up faster as bubbles, the drivers use this 'short cut' to check a loco before accepting charge.
  • MB1: Master Breaker 1: Selects the control stand 1
  • Aux: Auxiliary breaker: I wonder what this switches on ?
  • MB2: Master Breaker 2: Selects the other control stand
  • H/L: Breaker for the headlight 72 V, 250 Watt dual filament.
  • M/T: Manual Transition switch: Allows the loco to come from series parallel to full parallel combination when used manually, More on this subject later
  • Start: Push Button used to start the mother of all engines
  • Stop: Time for shut down: The switch is held for almost 15 - 20 seconds until all the pistons stop pumping and there is sudden silence !
  • ECS: Selector switch with a handle with Idle and Run positions - why is it required ?
  • MCO: Selector switch with seven position, from left to right : CO3, CO2, CO1, ALL IN, CO 4, CO5 and CO6. This is the motor selector switch to isolate a defective traction motor. The normal position is in the center - the ALL IN position.
  • GR: Ground Relay: Operates when a 'Power Ground' occurs i.e. the main generator short circuits !
  • Alarm Bell: Sounds before the engine is started ( for people working in the engine room and under the loco to clear the area) also when there is a fault like high water temperature or overspeed trip

Gauges located in the bulkhead:

  • FOG: Fuel Oil Pressure Gauge: Normal Reading: 1 Kg/cm2
  • LOP: Lube Oil Pressure Gauge: Normal Reading: 4 - 5 Kg/cm2
  • Booster Pressure: This is the Turbocharger (the railways call the Turbocharger 'booster') pressure gauge: Normal reading 1 - 1.5 Kg/cm2

One observation that I cannot explain is that when the loco is standing and the engine is taken to the 8th Notch, the Booster Pressure gauge does not show any reading although the engine is running at full revs. However it shows an indication during the run even on the 4th notch. Any explanations ?

Breakers located on the corner and the face of the control stand :

  • MUSD: Multiple Unit Shut Down: Shuts down all the locos connected in M U
  • MFFB: Master Fuel Pump Breaker, help at hand to stop the engine in a hurry ? Why are there two breakers for the Fuel pump ? Believe me this is a design question and the drivers can only guess an answer.
  • GF: Generator Field: Actually switches the field of the Exiter generator thus indirectly switching the main generator field.
  • MCB1: Not connected in this loco but I think it is related to the two pin power socket for a torch or a three colour (red/green/yellow) for night signaling use
  • Unmarked toggle switches for switching on the 'Classification Lamps' i.e. the smaller lamps under the headlamp
  • Rotary selector switch for the headlight: with provisions to switch off both the headlights, to dim either or both the headlights or to switch on both the headlights fully bright.
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