Comeng Faults from the Highlighted Courseware Flashcards
In cases of loss of traction power/critical power loss, what are the four initial things a driver must check?
Trips, switches, gauges and cocks
When checking “trips, switches, gauges and cocks”, what does the driver check in regards to the trip?
That it is set and lowered
When checking “trips, switches, gauges and cocks”, what does the driver check in regards to switches? (3)
- Switches are in normal position
- Circuit breakers are in normal position
- Doors Closed button is activated (steady blue)
When checking “trips, switches, gauges and cocks”, what does the driver check in regards to gauges? (3)
- Main res pressure is between 585 and 725 kPa
- Brake pipe is within normal tolerances (550 kPa)
- Control res air with normal tolerances (490 kPa)
When checking “trips, switches, gauges and cocks”, what does the driver check in regards to cocks? (2)
- BVICS is open (if BP is low)
- Red EC and Yellow TECHAV cocks are in normal position
Which tripped circuit breaker is most commonly the cause of a failed Comeng?
Control Circuit Breaker
What fault-finding method is undertaken if trips, switches, gauges and cocks have failed to locate the fault?
ROBBDS test (book 2 page 9, check phrasing of this question KT)
What does the ROBBDS test stand for?
Reverser
(Traction) Overload Reset
Brake Pipe Reduction
Control Governor Bypass
Door Loop Bypass
Second Controller
If an untouched train’s control circuit breaker is tripping, it is often a fault between:
The reverser to master controller cabling
How do we perform Step 3 of the ROBBDS test (Brake Pipe Reduction)?
- Make a BP reduction to below 325 kPa (Control Governor opens)
- Recharge BP pressure to above 430 (Control Governor closes)
- Try again for power
(If train gains power, the fault was likely dirt caught between Control Governor contacts)
Which reservoir supplies air pressure to operate switches within a Comeng’s main equipment case to transfer 1500v DC to the traction motors?
Control reservoir
Which three fault lights are connected to the traction system?
- Local fault light
- Line Switch fault light
- This Car light
How much air does the Control Reservoir hold?
490 kPa (+/- 20)
What effect will a faulty Control Reservoir have on a train?
It will cause switches to remain open and traction power will be unavailable on that car.
(Which switches? The courseware doesn’t specify)
In case of lack of traction due to a ruptured/isolated Control Reservoir, what happens to the Line Breakers and what fault lights/indications will a driver receive?
Line breakers will remain open. Line Switch fault will occur and no amps will be supplied to the motor car.
What should a driver do to manage a ruptured/isolated Control Reservior?
Traction Motors put to All Out and TMM submitted
How would a driver determine which pair of traction motors are defective on a motor car?
- Place Traction Cut-Out Switch to 1&2 position.
- Press Overload Reset button.
If fault lights still present, isolate 3& 4 instead and repeat.
According to courseware, what are the three major causes of loss of overhead power?
- Weak substation output or substation failure
- Overhead failure
- Defective 1500V DC circuits on Comeng trains
With loss of overhead power, the driver must stop the train and: (4)
- Check for derailment
- Contact Train Controller
- Secure the train
- Follow instructions from Train Controller to identify cause of power loss
According to courseware, 1500c DC equipment and circuits include: (5)
- Pantographs
- Associated Circuits
- Compressors
- Traction equipment
- Motor Alternators
When loss of overhead occurs, how many times will the system will automatically attempt to reset itself?
Twice
What happens to the saloon doors in a Comeng when overhead power is lost?
Doors will release
What will Metrol do if they are unable to restore overhead power?
Make a group radio call and request all drivers in affected area to lower pantographs
When lost overhead power has been restored, at what interval will Train Control instruct drivers to depart
At one minute intervals
If a train fails and the driver is unable to contact train control, can it be assumed a loss of overhead has occured?
No way. Gotta do fault finding first. Check those Trips, Switches, Gauges and Cocks etc.
What items can a driver check to confirm presence of 110v DC? (3)
- Bell
- EP operational
- Low Pressure flag is lowered
What items can a driver check to confirm presence of AC power items?
- Saloon lights (non-emergency)
- Van area cab light
- Operation of headlights
If a driver’s overhead is restored during fault finding, they must return to lead cab and raise pantos/start MAs. If they have no communication, how long must a driver wait before applying traction power? How far can they power?
- 30 seconds for UP
- 60 seconds for DOWN
Must remain in SERIES until next platform
If there is suspicion of disarranged overhead, what two personal safety measures must a driver take?
- Must remain in cab
- Must make PA asking passengers to remain on train
When loss of overhead occurs, how long will emergency lights run for?
Two hours
Loss of overhead:
How can a driver reset the emergency lights?
Toggle marker lights from auto to any other position and back
Loss of overhead:
How is a driver informed of the need to reset the emergency lights
Battery charger light will flash on driver’s fault panel
Loss of overhead:
How long will PA system be available for? How can it be reset?
Up to two hours. Reset when emergency lighting is reset
What is the purpose of the LSM (Loss of Overhead Shutdown Module)? How does it work?
To reduce the impact of 1500v DC defects from overloading the substation when lost overhead is returned. It works by switching off certain circuits when overhead is returned
What is the LSM speed threshold?
8km/h
Train moving OVER 8km/h and BVICS OPEN in lead cab:
If overhead power is lost and the 110vDC output drops to 95v DC for 2 continuous seconds, the LSM will activate and: (4)
- Trip the Ep circuit breaker (low pressure flag raises)
- Leave local motor alternator contactor set to on
- Shut down motor alternator
- Train can only be driven on air brakes
Rheostatic breaking deficiencies can only be diagnosed at what speeds?
Speeds above 8km/h
Train moving OVER 8km/h and BVICS CLOSED in trailing cab:
If the LSM is activated it will have what effect on the MA contractors? (2)
- Set the MA contactors to OFF in trailing cabs
- MAs will shut down due to loss of overhead supply in trailing cabs
Train STATIONARY and BVICS CLOSED in trailing cab:
If the LSM is activated it will: (4)
- Drop all trailing pantos
- Lead panto will be raised
- Leading MA contactor will be ON
- Trailing MA contactors will be OFF
(straight outta courseware)
Control Circuit Breaker Tripping – Master Controller Closed
The control circuit breaker may trip due to a defect in which 5 pieces of equipment on any motor car in the consist?
- Master controller
- Train cable
- Reverser equipment
- Traction power control equipment
- Rheo brake demand circuit
What are the THREE probable causes for the Control Circuit Breaker tripping in the following circumstance:
- Master controller closed
- Reverser in FWD, neutral, or REV
- Brake controller applied
- EP circuit breaker set
- Rheo brake isolate switch in normal
- Short circuit on the electric brake demand wire in the train cable
- Fault in the rheo brake control equipment on any motor car
- (not highlighted in courseware) Short circuit between control circuit breaker and master controller
How is the train cable connected between two centre motors?
Through spring-loaded contacts in the Scharfenberg coupler
What will a driver observe if the Control Circuit Breaker trips when operating the Remote Panto Up or Remote Panto Down buttons (2)
Remote Panto Up: Pantos cannot be remotely raised
Remote Panto Down: Pantos cannot be remotely lowered
What will a driver observe if the Control Circuit Breaker trips when operating the Overload Reset?
Driver will observe that overloads cannot be reset
What will a driver observe if the Control Circuit Breaker trips when operating the Master Controller?
Driver will observe that they cannot get traction power in one or all powering positions
What will a driver observe if the Control Circuit Breaker trips when operating the rheo brake?
Driver will observe a failure of the rheo brake
How many running Motor Alternators are required to provide the train with a 110v DC supply?
One (though it will be in a degraded mode)
What will the effect on a three-car unit if one motor alternator stops working? (4)
- Saloon lighting at 50% capacity
- Air con at 50% capacity
- Cab lighting and heating at 50%
- Local rheo where MA has failed will be inoperative
How long after loss of overhead until the VICERS Activation Valve will open, causing brake pipe to exhaust to atmosphere?
5 minutes
If lost overhead is likely to be caused by a defective train, how will Metrol ascertain which train contains the defect?
One by one, Metrol will request a train raises all pantos and starts all motor alternators. When overhead is lost again, it will indicate the defective train.
At what pressure does the safety valve open on a Comeng?
775 kPa
What are the two pressure settings on the compressor governor?
HIGH (725 kPa)
LOW (585 kPa)
Fill the blank:
If brake pipe pressure cannot be maintained above ____ kPa, declare the train disabled and make arrangements for relief
425 kPa
Are the compressors able to run continuously if required?
Yes
How can a driver ascertain which faulty compressor governor is causing the compressors to run continuously?
((what extra thing should they check?))
Electrically cut-out each compressor governor in turn until the compressors stop operating.
(Compressor must be cut back in before moving to next compressor)
((Also, check iso cock is not turned))
How can a driver manage a faulty compressor governor which is causing the compressors to run continuously, if the train is in running or if there is no time to fault find at the terminal station?
Driver should isolate compressor governor in lead motor and continue driving.
What two indications might a driver get from a minor leak within the main res air system? (2)
- MR air pressure falling
- Air compressors running continuously
What are the main res air systems on a Comeng? (10)
SWAMP BED CC
- Spring park brake system
- Whistle
- Air suspension
- MA contactors
- Pantographs
- Brake pipe charging
- EP braking system
- Door system
- Compressor governor
- Control res system
What eight things can cause a FDCL if the doors are closed?
- Control Circuit Braker tripped in a rear cab
- Rear motor tail lights turned off
- Auxillary Circuit Breaker tripped in another cab
- PLC circuit breaker tripping in any trailing car
- Door System Faults
- Open circuit in the Train Cable
- The train not registering a decoupling having taken place
- Second BIVCS open
What lights on the fault panel are likely to illuminate in the case of saloon light defects? (3)
MA
AC
“this car” (if applicable)