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AuthorTopic: Losing power while leaving station at 2mph (Read 1,155 times)
pacific
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Losing power while leaving station at 2mph
« Thread Started on Nov 4, 2006, 4:01pm »
I'm curious as to why this sometimes happens as it's occured more than once before.

The doors shut and the motor powers up to full power, then suddenly cuts off! Half a second later, the motor powers up again and we accelerate normally.

I'm just curious to why that happens as it is pretty jerky! ;D

For the record, only had it happen at Bethnal Green (EB andWB) since I only take the Central often between Liverpool St. and Mile End.
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Re: Losing power while leaving station at 2mph
« Reply #1 on Nov 4, 2006, 4:03pm »
Might be that people were pushed up against the doors, thus causing the motors to drop out due to the loss of pilot light?
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Re: Losing power while leaving station at 2mph
« Reply #2 on Nov 4, 2006, 5:40pm »
Is there a section gap there? Help me out Artery!
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Re: Losing power while leaving station at 2mph
« Reply #3 on Nov 4, 2006, 9:22pm »
I don't think it is a section gap otherwise i† would happen at the same place all of the time. I think it may be pilot light as quite often when this happens the train op comes on and starts complaining about people leaning on the doors.
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Re: Losing power while leaving station at 2mph
« Reply #4 on Nov 5, 2006, 2:14am »
The main reason for loss of traction (motors) when starting from a station is indeed a loss of pilot light - but it's not the only reason ;) ;D ;D

There are usually two main causes for a loss of pilot light in this scenario - the first has already been mentioned (passengers leaning on the doors). The second cause is where there is a gap in the current rails (section gap not really being of any relevance); as the train's shoes pick up the current rails again at slow speed, the resulting arc which sometimes occurs cause's the train to "lurch" - which in turn, cause's a loss of pilot light (the train door interlocks are sensitive things you see ::)).

In both these cases, moving the CTBC to the 'Off & Release' position will usually bring back the pilot light (on C & D stocks at least).

Another candidate, though less likely, are the overloads. I'm not that technically minded, but I do know that it's to do with the traction current supply to the motors - if there's an overload, the contacts break, and we lose power. Pressing the 'Overload Reset' button is the cure in this case. Again the CTBC will more than likely have returned to the 'Off & Release' position as it's normally the first reaction the driver will make in response to any problem - hence the impression of a brief lack of motoring.
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Re: Losing power while leaving station at 2mph
« Reply #5 on Nov 5, 2006, 9:13am »
It also occurs at Oxo C e/b... and it's not every train that does it either... Variety of factors include misaligned collector shoes, possible overload. There's a Section Gap at Bethnal... but I never really notice anything... I don't get a message on the DTS monitor about Traction supply probs...
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Re: Losing power while leaving station at 2mph
« Reply #6 on Dec 6, 2006, 2:14am »
So my two second release of the ATO start buttons might have been right.....wish I'd never deleted it now......
« Last Edit: Dec 6, 2006, 2:15am by The Major »Link to Post - Back to Top  IP: Logged
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