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Post by tube10 on May 13, 2005 15:57:09 GMT
do u know of any underground train that uses the chopper control for regenerative braking that makes a buzz when the train starts to move
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Colin
Advisor
My preserved fire engine!
Posts: 11,310
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Post by Colin on May 13, 2005 18:26:12 GMT
As far as i'm aware that is only used on the main line.
Q8 asked something similar in a thread titled 'choppers' in the general questions section.
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Post by igelkotten on May 20, 2005 11:15:45 GMT
Aren't the 95 & 96 TS supposed to be capable of regenerative braking?  Anyhow, the "buzz" you hear, and which is especially pronounced on vehicles with AC traction motors, is an inherent part of the traction control equipment. Thyristor control, sometiems also known as chopper control, generally works on the principle of chopping up the traction current in small pulses, thereby controlling the speed of the traction motor. The buzz you hear is, essentially, the switching frequency of the traction control units, amplified through the equipment cases it sits in and the carbody it is mounted on. Old-style thyristor bridges and DC mostors are actually quite silent, and do not make that much of a buzz. GTO thyristors use a slightly different principle of construction, and have a very pronounced "gear-shifting" sound when accelerating and braking. IGBT control with AC motors gives a characteristic buzzing whine that goes up and down in frequencey according to the load on the traction motors. |
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Post by Christopher J on May 20, 2005 22:24:08 GMT
Aren't the 95 & 96 TS supposed to be capable of regenerative braking? I know for sure the 96's are capable, not sure about the 95's. The Regen Brake on the 96's is currently disabled because of major problems that occur when the juice from the motors is sent back into the system. One example is that when the juice is sent back, the esleclators on the Jubilee Line Extension think they're the next Michael Schumacher and start accelerating at quite a rapid speed.  The same happens on the Central Line with the 92's, but it's not half as bad as what happens on the Jubilee Line with the 96's. |
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