Quote:
Originally Posted by Swapnil4585 A piece of information that I would like to share.
The Nagpur loco shed has come out with a technique to produce electricity out of energy produced when brakes are applied by the pilot. The said technique is being deployed on all the WAG - 9 class of electric locomotives belonging to the Nagpur shed.
The Nagpur - Itarsi section have a large number of inclines. Therefore, the pilots need to use the brakes, the 'Dynamic Brake' in particular, frequently (a loco has 5 different types of brakes). The friction between the brakes and wheels shall cause to produce electricity. How and where this electricity is stored, is not explained in the article that I read in our local newspaper.
The Nagpur shed has been doing this since April, and it has managed to save 1.06 crore units of electricity so far. Indian Railways have 272 WAG - 9 in its arsenal, out of which 140 belong to Nagpur. |
This is called dynamic braking. This can be retrofitted to all types of locos, but the regeneration capacity is limited only to 3 Phase locos- WAP5, WAP7 and WAG9.
How it works:
1. Each loco has traction motors attached to its wheel axles. They are fed electricity from OHE, and provide traction to the Locomotive in normal usage.
2. When the loco needs to brake, the traction motors act as generator and generate electricity which is fed back to OHE (in case of 3 Phase Locos) or dissipated through heat by DBRs (Dynamic Brake Resistors) in case of other locos.
3. This provides additional braking capacity to the locos, and hence reduces the fatigue on the loco's braking system.
4. Contrary to the post- A loco has only its own brakes, and regenerative braking (if traction motors are enabled to work this way). Each coach/wagon has its own brakes which are operated using the air pressure generated from loco. These are called air brakes, and can pressurized air travels across the hose pipes across the train. These hose pipes can be seen at the coach ends where coaches are coupled.
5. The regenerative braking works not only in sections with inclines, but on flat sections too. However it is preferred on the inclines as it reduces the fatigue on engine brakes and hence reduces chances of brake failures. For a loaded freight/Passenger train, a brake failure can be catastrophic on gradients.
6. Regenerative braking is used across IR and not limited to Nagpur shed. (By the way, shed's name is Ajni, where the 3 Phase locos are based out of)
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Originally Posted by sandeepmohan A locomotive like the WAG9 has the ability to send power back to the grid via regeneration. This is how power is saved. Its not via traditional braking though. This will cook the brakes. The traction motors basically work in reverse, sending power back to the grid. This is also known as regenerative braking.
Indian Railways has become more and more critical about power saving. Power consumed and returned from and to the grid is calculated at the end of every trip. The locomotive pilot logs this information by the end of his/her shift. |
Relatively better description of how the system works. The regenerative braking is not only used in regular trains, but the metro trains as well. It results in power saving and reduces the carbon footprint.
Here's the link for the statistics on the power consumed- relatively old, but would give a fair idea of the energy bills of IR.
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Originally Posted by A350XWB I'm curious to know how the normal wheel brakes are used to generate electricity (if true). Also, I would like to know what are these 5 different types of brakes that is mentioned in the post.
Diesel-electric locomotives also utilize dynamic braking, but they cannot send the power back to the grid. The power generated as a result of dynamic braking is dissipated through a resistance grid placed on the top part of the loco. That is some serious wastage of power |
Here are some examples of the DBRs
WDM3A's DBR- can be seen between the driver's window and the headlight, on the top side
WAP4's DBR- circled- the pic is from Daulatram's website, who are the leading manufacturer of DBRs for Indian Railways
WAM4's DBRs- this one has massive ones on its roof.
Note all these 3 loco types use dynamic braking but not regenerative braking. The difference is that regenerative braking sends power back to the grid.
Hope this clarifies.