DIESEL LOCO - Power Ground

DIESEL LOCO - Power Ground 

Earth fault occur in power circuit is called power ground. When earth faults in traction motor, traction motor cables, BKT, REV, power contactors, GR1 operates with indications. Check following items - 1. Traction motor cables are tightened properly. 2. If there are any metal or wire pieces in between BKT/Rev./Power contactors, remove it. 3. Check the wire connection of load meter. 4. If there is smell or smoke from any TM, isolate it. Note

1. If power ground comes on higher notches, work on lower notches. 
2. TM 4, 5, 6 can be isolate through MCO, if additional contactors (AC1, AC2, AC3) are provided on back panel, then TM 1, 2, 3 can be isolated through MCO in case of power ground. 
3. When GR1 operate during dynamic braking don’t use DB.
4. Loco is provided with GR1 and GR2 and during engine starting, if GR2 operates. In this condition first start the engine, then reset it. 
5. One GR is provided in WDM-2 loco. At the time of engine starting, if GR operates. In this condition first start the engine, then reset it and note down in the repair book.

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Wheel Slip

The process of wheel slipping is called wheel slip. When the difference of current occurs between two traction motors then related WSR will energize with the following indications –

 

1. Wheel slip lamp will glow. 

2. Buzzer sounds. 

3. Automatic sanding takes place. 

4. Load meter fluctuates. 

 

Momentary Wheel Slip - Momentary wheel slip occurs whenever there is oily and wet track, during transition, while opening notches quickly. To avoid this reduce the notch and apply sanders. 

 

 

Motor Cut out Switch It is a rotating type switch provided on front panel. It is used to isolate the TM. It has 7 positions.

 

 

How to Operate MCO 1. MH should be kept to idle position 2. Break the MCO seal. 3. Rotate the MCO from All IN position to CO1, CO2, CO3, CO4, CO5, CO6 position. After Isolating TM By MCO:  1. Series power contactor will not pick up. 2. Only five parallel power contactors will pick up. 3. Transition will not come. 4. Dynamic brake isolated. 5. Load meter will not showing current, if TM-1 is isolated.

 

Load Meter

 

 It is provided on both control stands. It shows current in TM. During dynamic braking load meter shows generated current. It has two colour strips on the scale, green colour strip shows unrestricted zone and red shows restricted zone. Each marking on scale shows 100 amps. Green strip shows up to 1000 amp. Red colour strip having 60, 12, 6, 4 it shows minute. When load meter needle goes in restricted zone, observe time restriction shown by needle. Load meter shows 1/3 rd part of total current in SP combination and 1/6th part in parallel combination. Load meter have yellow/Red dot on 600 amps. During dynamic braking, when loco speed more then 90 km/h, load meter needle should not exceed yellow/Red dot, when loco speed is less than 90 km/h current should not exceed 800 amps.  Note 1. Load meter shows Ist notch current 300 amps. 2. Load meter is connected with TM-1.It will not show current reading if TM -1 isolate. 3. If both load meter showing different reading. Which one showing, 300 amps Ist notch current is correct. 4. If both load meters are defective then open the higher notch, after loco speed on/above 23 km/h.