Regenerative/Dynamic Brakes – Part 3: Example of using a Locomotive in Regenerative Brakes

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As promised, this is the third part on Regenerative/Dynamic Brakes. I was able to use Bennie’s old 6E manual and thanks to another Route Supervisor – Gerhardus Kruger – for the use of his book: Transnet List of English – Afrikaans Terms which helped with the translation of certain phrases. Gert also played a role in producing this book for Transnet back in the late ’80s.

I decided to use what is now an old locomotive – the 6E/6E1 – but you can still get an idea how Regenerative Brakes are used in every day situations. Below is an excerpt from the 6E manual. Once again, it is technical. I decided to use this locomotive as it’s one of my favourites.

Here is a snippet of information from a Wikipedia Article written by Andre Kritzinger:

‘The Class 6E1 was produced in eleven series over a period of nearly sixteen years, with altogether nine hundred and sixty units placed in service, all built by UCW. This makes the Class 6E1 the most numerous single locomotive class ever to have seen service in South Africa and serves as ample proof of a highly successful design.’

The full article about this and all other South African Locomotives can be read at: http://en.wikipedia.org/wiki/South_African_Class_6E1,_Series_1

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36. Operation of Trains in Regenerative Braking

36.1 Setup of Regenerative Brakes

36.1.1 Make a minimum brake application of 16 – 20 kPa for around 60 – 90 seconds, depending on the length of the train, before descending on the down gradient. Operate the Train Brake to manage the speed of the train. Switch the Accelerator Lever from Full Field to Off Position as soon as the gradient changes to a down gradient.
36.1.2 Place the Reverser Key in the required combination (Series or Parallel).
36.1.3 Place the Regenerative Brake Lever in the first notch and wait until the Field Ammeter gives a reading. When the Field Ammeter registers, notch up the Regenerative Brake Lever until the Motor Voltmeter and the Line Voltmeter are balanced.
36.1.4 When the meters are balanced, place the Accelerator Lever in the first notch, see that the Line Switch Indicator extinguishes and watch the Armature Ammmeter. Make sure that it registers zero and setup the Regenerative Brake Lever when needed. When the Armature Ammeter registers zero, move the Accelerator Lever with a consistent movement to the Full Field position. Slight Motoring Reading will be used preferably to prevent the locomotive/s from tripping out of regenerative brakes. (This is why it’s important for the Train Assistant to give the Driver the regen readings on the rear locomotives to avoid jerking when the Driver goes into regen – Bennie Jordaan)
36.1.5 Place the Independent Brake Valve in the Proportional position.
36.1.6 Set the Regenerative Brake Lever to the highest notch depending on the gradient, load, speed limit, Motor- and Line Voltage and so forth, and place the Driver’s Brake Valve in the desired position. The speed of the train must be managed by the use of the Train Brake until the Accelerator Lever is in the Full field position, and the Regenerative Brake Lever is in the highest notch. After the Train Brake is released, the speed of the train will be managed by the use of regenerative braking. If needed, the Train Brake must be used to control the speed of the train and to control the voltage from the Traction Motors.

37. Setup of Electronic Regenerative Braking on 17E Locomotives (Refer to Wikipedia articles to see how a 17E is relevant here – Jade)

Regenerative Braking can be used at speeds higher than normal and the balancing of the readings on the Line Voltmeter and Motor Voltmeter is not critical.

38. Speed During Regenerative Braking

38.1 During regenerative braking, the speed of the train must never be at higher speeds than what normal running times allow. The locomotives are not designed to change to other combinations during regenerative braking. The Train Driver must decide on which combination (series or parallel) to use before setting up regenerative braking.

38.2 The Speed During Regenerative Braking:

38.2.1 Series Combination: 22,5 km – 48 km per hour.
38.2.2 Parallel Combination: 43 km – 90 km per hour.

38.3 It is better to start the down gradient at a lower speed than the speed actually wanted to be driven at.

38.4 The closest maximum speed where regenerative braking can be setup:

38.4.1 Series Combination: 37 km per hour.
38.4.2 Parallel Combination: 64 km per hour.

39. Managing the Speed of the Train

39.1 As a result of high Axel Loads, sometimes the catenary wire cannot accept all the current back on the amount of regenerative braking being used, in this case, the Train Brakes must be applied to control the speed of the train. Then speed restrictions can be managed by the use of the Train Brake occasionally and then notch up the regenerative brake lever. If the speed is so low that the Armature Ammeter indicates powering, the Regenerative Lever must be notched up towards the 16th notch and place the Locomotive Brake Lever into proportional incase of a trip out. It might be necessary to put the train brakes on in a dangerous situation if the Armature Ammeter and Field Ammeter readings extremely differ.

39.2 Regenerative Braking is designed to keep a train at a constant speed whilst on down gradients. Notching up of the Regenerative Brake Lever to reduce speed can make the Over Current Relay or Overload Relay trip, causing the wheels to slip.

39.3 There will be circumstances when the right speed cannot be maintained. For example, the load can be limited to a speed that’s either too high for Series Working or to low for Parallel Working. In such instances, the locomotive must be worked in Series and the regenerative brakes must be helped partially by the use of Train Brakes.

39.4 The stopping distance of the train can be significantly reduced by the locomotives in Regenerative Combination while the Train Brakes are used. When the Armature Ammeter moves towards zero, the Accelerator Lever must first be moved to off and then the Regenerative Brake Lever.

39.5 The Train’s speed and Armature Ammeter Readings can change with different gradients regardless of the position of the Regenerative Brake Lever. If the gradient becomes steeper, the speed and Armature Ammeter reading will increase. If the gradient becomes level, the speed and Armature Ammeter reading will reduce. The Regenerative Brake Lever must be used appropriately (notched up or down) to match changes in gradient and to keep the train at a constant speed. The position must only be changed when the changes to the gradient are reasonable enough. The use of sand is recommended while the Regenerative Brake Lever is being notched up.

39.6 The Train Brake must partially be used if the wheels slip during regenerative braking until the wheels stop slipping. Sand must not be used to stop the wheels slipping. (This is to prevent the wheels from locking therefor breaking gear teeth. It is better to notch down to avoid slipping wheels. The Driver can first apply sand before notching up in regen to avoid wheel slip – Gert Kruger)

39.7 If the Train Brake is partially used to control the speed of the train, the Train Driver is not allowed to make a brake application less than the usual Minimum Application.

40. Reducing speed during Regenerative Braking

40.1 The Train Driver must change to a lower Combination if circumstances call for the train to travel at a lower speed.

40.2 If it is not necessary to switch to a lower Combination, handle the train as follows:

40.2.1 Make a Minimum Brake Application or, if the Train Brake is already partially applied, reduce the application. When the application becomes effective, the train’s speed will reduce. When the train’s speed reduces, the Armature Ammeter reading will also go down.
40.2.2 When the Armature Ammeter reading drops, move the Regenerative Brake Lever one notch up. The Armature Ammeter reading will show a higher reading and care must be taken to ensure that the Armature Ammeter reading does not go higher than the original reading.

40.3 While the Regenerative Brake Lever is occasionally notched up, according to reducing the train speed and Armature Ammeter reading, the Train Driver sets up the Regenerative Brake Lever in a position to reduce the speed of the train without jerking, bundling up or going out of regenerative braking.

41. Switching out of Regenerative Braking

In the case of more than one locomotive, the Train Driver must keep in mind that the rear locomotive/s, can give a lower or higher Armature Ammeter reading. Under these circumstances, when going out of regenerative braking, the Train Driver must come out of regenerative braking carefully to avoid unnecessary jerking of the train.

42. Switching out of Regenerative Braking on a Down Gradient (Not Stopping)

42.1 Put the train brakes on a Minimum Application and then steadily increase the brake pressure. Once the brake application has gone through the train effectively, the speed and Armature Ammeter reading will decrease. Wait until the Armature Ammeter indicates zero.

42.1.1 Place the Independent Brake in the Release Position.
42.1.2 Place the Accelerator Lever in the Off Position.
42.1.3 Place the Regenerative Brake Lever in the Motoring Position.
42.1.4 Using the Train Brakes, continue to manage the speed of the train.

4.3 Changes to Regenerative Braking Combination on a Down Gradient

43.1 Because changing the combination while in regenerative braking is not possible, first come out of regenerative braking before changing to another regenerative braking combination.

43.2 Follow the directions in paragraph 42. to come out of Regenerative braking.

43.3 Place the Reverser Key in the required position and apply the Train Brake to change the speed for the Regenerative Braking combination needed.

43.4 Setup the Regenerative Braking in the usual manner.

44. Train movement from a Down Gradient to level or Up Gradient

44.1 When the gradient begins to smooth out, the train’s speed and the Armature Ammeter reading will decrease. In a constant manner, notching down the Regenerative Brake Lever as the gradients smooths out the Regenerative Braking Power decreases consistently because the train’s speed stays constant.

44.2 If the Regenerative Brake Lever is notched down too quickly, the locomotive will most likely switch to motoring which will result in a violent jerking of the train.

44.3 The Armature Ammeter must be watched closely to ensure that the Regenerative Braking reading decreases in a constant manner. When the Armature Ammeter registers zero, the Train Driver must –

44.3.1 place the Independent Brake in the Released position.
44.3.2 place the Accelerator Lever in the Off position.
44.3.3 place the Regenerative Brake Lever in the Motoring position.
44.3.4 continue to handle the train in an appropriate manner to surrounding conditions.

45. Stopping During Regenerative Braking

45.1 Progressively apply the Train Brakes until the train is under control. When the Armature Ammeter reading is at zero, put the Independent Brake in the Released position, the Accelerator Lever in the Off position and then the Regenerative Brake Lever in the Motoring position.

N.B: The Accelerator Lever and the Regenerative Brake Lever must never be notched up or notched down at the same time. It can result in huge damages and must thus be avoided.

45.2 The Independent Brake must be moved to the Released position before the Accelerator and the Regenerative Brake Levers are pushed back.

46. Emergency Stop in Regenerative Braking

46.1 Fully apply the Train Brake and Independent Brake and apply sand progressively on the rails. As the Armature Ammeter Needle moves closer to zero, place the Accelerator Lever in the Off position and the Regenerative Brake Lever in the motoring position. Place the Independent Brake in the Proportional position.

46.2 keep the brakes applied until the train stops or until it is clear that there is no need to stop.

47. Bringing a Train in Motion in Regenerative Braking

47.1 The locomotive is not designed to depart in the Regenerative Braking the reason being that the Armature Current can rise too high. When it is required to depart in Regenerative Braking, such as immediately before a steep down gradient where speed restrictions are in place, continue as follows:

47.1.1 Place the Reverser key in the Series position.
47.1.2 Place the Regenerative Brake Lever in the first notch, check that the Field Ammeter registers and move the Regenerative Brake Handle towards the 16th notch.
47.1.3 Release the Locomotive Brakes and place the Independent Brake in the Proportional position.
47.1.4 Place the Accelerator Lever in the first notch to slowly bring the train in motion. Increase the speed of the train by carefully notching up the Accelerator Lever as in normal driving conditions. Use the Train Brakes when required to control the speed of the train.
47.1.5 Set the Regenerative Brake Lever to accommodate prevailing conditions.

48. Rolling Sections

48.1 Sections sometimes change with short up gradients that require light Motoring. There can be instances in such sections where Regenerative Braking can be used.

48.2 The recommended maximum ratio from Field Current to Armature Current is as in the case of working in Regenerative Braking.

49. Resistance Blowers – Locomotives equipped with a “C”- Drum

When switching out of Regenerative Braking, and the Resistance Blowers fail, the Train Driver will be obliged to bring the train to a standstill and then set the Resistance Blower Switch – Drum Switch, where provided, (C – Drum no. 2 High Tension Compartment) correctly by hand.

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