Quote:
Originally Posted by ECML43
thanks Wyvern, now i think about it that's pretty ingenious. but tell me... (if you know) why does the thyristor on the 3/465 EMUs appear to have several frequency build ups one after the other each sounding the same. the LU 1996 (jubilee line) stock does this too.
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Networkers have asynchronous AC motors (even though they're DC stock, which means they have to use Invertors to convert DC-AC).
So to accelerate the train the traction convertors increase the frequency of the 3-phase current going to the motors. Thats what the increasing frequency of whining is. The motors don't run at exactly the same frequency as the supplied current, they lag behind a bit, depending on the amount of torque applied.
HTH
FP (ex Networker driver who got sick and tired of the whining noise
).