IRI member Amit Jha and Harsh started the topic of Pantographs and discussion was ended with no conclusion. Here I took a step forward to answer the controversial question of Mystery of Pantographs.
I would request everyone to read the full article first then comment !!
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Why does sometimes we see Front Pantograph used and sometime rear one in Winter or any Season?...
more...
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First of all we need to know few codes of conduct made by IR for AC Locos.
1)According to IR/Codesmanual/ACTraction-III/Chapter IV
Usage and authority over pantograph of various officials are issued under-
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30604- Duties of LP- The Driver/motorman shall keep a special watch on the pantograph of his own train as well as passing electric trains and report any abnormality as soon as possible to TPC/TLC. If he notices any serious defect in the pantographs which are likely to cause damage to OHE, he shall stop the train forthwith and convey details to the TPC/TLC on duty.
*So,Clearly LP does''nt have any authority to select Pantograph on his own.
30627- Use of Pantographs-1. The rear pantograph of the loco (in the direction of motion) should normally be used by the Driver. The leading pantograph may be used only if the rear pantograph is defective or damaged or specially instructed.
2. Loco should not be worked with both the pantographs raised.
3. For normal lowering of pantographs the Master Controller should be switched off and the circuit breaker tripped before the panto-selector is moved to position "0. In an emergency when the locomotive is in motion, the pantograph may be lowered by using the panto-selector switch, even without tripping the circuit breaker but after bringing Master controller to '0' position.1. The rear pantograph of the loco (in the direction of motion) should normally be used by the Driver. The leading pantograph may be used only if the rear pantograph is defective or damaged or specially instructed.
2. Loco should not be worked with both the pantographs raised.
3. For normal lowering of pantographs the Master Controller should be switched off and the circuit breaker tripped before the panto-selector is moved to position "0. In an emergency when the locomotive is in motion, the pantograph may be lowered by using the panto-selector switch, even without tripping the circuit breaker but after bringing Master controller to '0' position.
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Secondly,we must know consequences of winter season in India Correctly.
1) fog is made up of condensed water droplets which are the result of the air being cooled to the point (actually, the dewpoint) where it can no longer hold all of the water vapor it contains.
2) During Winter days Atmospheric pressure increases and precipitation decreases condensation happens of water droplets along with other foreign gases which may form any kind of compound according to elements it has...which causes sticking of solid materials on CATENARY WIRE.
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Thirdly we should know a little bit about Pantographs.
As given in pictures...we can see 2 metal strips on pantograph head. Generally first strip is Brass plated which is used to push/pull the impurities offf the wire. Second one is the main strip which is carbon molded which is used to obtain power. Image of Indian Loco Class WAP 7
Ohkay Now we are good to go...!!!
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In Case of eLoco the DBR is overhead and under the Pantographs which is the most sensitive equipment which works as SMPS of inner machinery. In case of winters in India on sometimes we see Front Pantograph Up which is abnormal according to IR ACtraction Code. The reason behind may be simple as that..'
a) If LP observes any problem in the rear Panto then he can inform TLC/TPC who can direct LP to stop using Rear panto for a change.
b) More complex reason is in winters OHE wires can be impure on its metal in various parts because of the weather reasons described above. Now, In case of winters OHE can be impure so here is the mechanism of both pantos over wire - Front > (Pushes the impurity ahead proportionate to the speed of the loco less chances of debris on DBR), Rear < (Pulls impurity and which can cause fatal by pulling the debris inside DBR). So Front panto is used to keep the Loco safe during Winters.
Pantographs were first designed by Francis Galton to scale down atmospheric temperature and which concept was first used in Sweden for Rail. So basically Pantograph design is based on Sweden rail. ADD(Automated dropping device) was used in Sweden and other countries for dropping the Panto whenever problem arises automatically. Swiss rail also uses same technology but ABB couldn't provide that to IR in its latest loco batch because for Installing ADD copper strip is required not carbon but in the diverse atmospheric condition copper would get rusted in India so which means the problems of pantograph is not yet solved in IR.
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FAQ-
1) Why in dense fog trans achieve bullet speed in other countries but not in India?
First reason is ADD absence. In winters in India Visibility is very low in northern zones but that is the figurative reason for slow speed. Scientific and technical factor is the Brass moled strip is very deadly in case of interaction with foreign materials other than wire metal. Thats why you see little sparks during the run. Now, If high speed is maintained Brass strip can get in contact with foreign compound present on the wire due to atmospheric conditions which are described above and can generate 3000 degrees heat which can result in glueing of Panto and OHE wire and Pantograph will get broken and will result in fire and results may be catastrophic. Thats why trains are kept at 20-50 K's in Fog due to this reason also. This consequence is for effective if Front Panto is up because Brass strip faces front and which creates greater Force in comparison to Rear. Thats why we see some trains to achieve MPS in low visibility too.
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2)Why Diesel locos face problems in IR during winters?
a) If diesel loco moving in Electrified zone- Simple, the section is full of eLoco trains and they are being slow due to reasons described above so to maintain run diesel loco trains also get delayed. For ex- If 12301 is going @20K's and a diesel train is behind which can go atleast at 60-70k's inspite of visibility then would IR allow that train to Overtake 12301. NO !!!Also the toxic gas which diesel Loco leaves also creats compounds on OHE wires.
b)If diesel loco is moving in fully non electrified zone such as NFR,NER,KR etc.- Visibility matters in that case !! Usually we see fully non electrified zones have Single BG or max Dual BG.In case of both the train running ahead is getting a little slow due to visibility but the cumulative effect lies on the train coming from behind because it can Overtake plus the train in behind also has visibility issue so this cumulative effect results in delay of diesel trains in India
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3) Why we see front panto up in summer/autumn too ??
As I stated according to ACTraction III / CH IV if LP observes any kind of compromising thing in the pantograph of his loco or other then he should inform TLC who may suggest to change Panto later thats why this can happen in any season not only in winter.
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4)Is there any directives of IR regulation to use Panto specifically in any zone and in any season??
NO. This choice solely happens during travel.LP doesnt have the authority or directives to change it. In case that he feels to get it changes...he have to discuss the matter with TLC and approval must be given by S.Engg/Sr.DEE whom may consider any theory which is not really known.
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5)What in Case of DC traction?
Generally, WCaM locos have two Pantograph for AC and DC each. Usually in IR the question never arises because DC traction is only present in CR which is not prone to such winter as compared to NR/NCR. But still same procedures can be taken on Wcam Locos too.
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6)Why this never arises in case of rainy season??
In rainy season Precipitation gets higher and Atmospheric Pressure gets lower which results in other gases to gain a height. So, lesser chances of impurity on OHE. Basic water is not having such weight which can effect DBR and also speed of Loco splits the water molecules in the air which results to just few sprinkles over DBR which is totally ineffective.
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This article is result of my research of various facts and history of Rail and applied sciences. I also interviewed few personals involved with ELS Engg. Dept.
This research may have faults and deviations !! All the learned friends of mine are welcome to discuss it further but I would request not throw comments without any valid reason or reasonable resonance. I also Conclude that..Usage of Pantograph is very controversial and vulnerable because no pattern of use is not yet observed. It will be the same untill and unless ADD is installed which is quite impossible with the use of Carbon strips.
Thankyou !!_/\_
