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Post by nickf on Jun 24, 2010 10:23:36 GMT
I have read that in the early days of electric traction on trams and Underground trains that the transition between series and parallel working could be jerky until bridge transition was introduced. Do the new methods of thyristor and IGBT control replace this transition from series to parallel or is bridge transition still used?
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North End
Beneath Newington Causeway
Posts: 1,769
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Post by North End on Jun 24, 2010 10:47:19 GMT
I have read that in the early days of electric traction on trams and Underground trains that the transition between series and parallel working could be jerky until bridge transition was introduced. Do the new methods of thyristor and IGBT control replace this transition from series to parallel or is bridge transition still used? On stocks built since 1992 (also 1986 stock?), there is no such thing as series & parallel. The TBC is effectively stepless. From memory, on a 1995 stock the Train Operator selects a motoring position on the TBC, this is converted to an electrical PWM signal by the Encoder, which is fed to the Propulsion Inverter Electronics (PIE), which then instructs the Propulsion Inverter Module (PIM). The PIM is the device which converts the 630vDC from the current rails to variable 0-415vAC at the traction motors. 92, 96 and 09 stocks emulate this more or less, but with significant differences taking into account the technology available at the time the stock was designed. |
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Post by nickf on Jun 24, 2010 13:46:30 GMT
Many thanks. Yet another technology escapes from my understanding! I could cope with resistances and bridges and interpoles but now......ho hum; I used to understand how phones worked too.
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Post by 100andthirty on Jun 24, 2010 16:40:13 GMT
On stocks built since 1992 (also 1986 stock?), there is no such thing as series & parallel. The TBC is effectively stepless. From memory, on a 1995 stock the Train Operator selects a motoring position on the TBC, this is converted to an electrical PWM signal by the Encoder, which is fed to the Propulsion Inverter Electronics (PIE), which then instructs the Propulsion Inverter Module (PIM). The PIM is the device which converts the 630vDC from the current rails to variable 415vAC at the traction motors. 92, 96 and 09 stocks emulate this more or less, but with significant differences taking into account the technology available at the time the stock was designed. I need to correct one or two things..... 1) '92ts still uses DC motors, so there's no AC output from the converter but variable voltage DC. The voltage to the armatures (the rotating bit) and the fields (the static bit) can be varied independently 2) All the later trains - '95, 96, '09, S stocks use AC motors. The converter delivers VARIABLE frequency and VARIABLE voltage in order to control motor speed and torque |
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Deleted
Deleted Member
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Post by Deleted on Jun 24, 2010 20:38:46 GMT
I have read that in the early days of electric traction on trams and Underground trains that the transition between series and parallel working could be jerky until bridge transition was introduced. I was travelling on a packed 72ts the other week and you could feel it jerk everytime a resistance was cut by the RPA as we pulled out of each station. I was sat over the RPA and each jerk seemed to be timed with a click of it. |
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