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Re: Recent derailments - Metro North
Author: fkrock
Date: 12-06-2013 - 10:00
In San Francisco the PCC cars built originally for St. Louis had spring applied friction brakes (the 1100 series cars). St. Louis did not have any lines on hills like San Francisco. These brakes would not hold the car when it stopped on a grade so operators applied track brakes with a switch on the dash to hold the car stationary.
Cars built for San Francisco, the 1000 series cars, would hold when stopped on hills.
Whether regenerative braking will work on electric lines depends on how the traction power is created. Under certain conditions regenerative braking power can be fed back into the power company grid when there is no or minimal load on the traction power buss. However if DC traction power is generated with a mercury arc or solid state rectifier, power cannot be fed back into the power company grid with existing equipment.
Early electrification, such as New Haven or Pennsylvania RR, used lower frequency AC for traction power at 25 Hz so feeding back into 60 Hz power company lines would have been difficult. The lower frequency AC was used because of inductance problems with early design AC motors.
Cars built for San Francisco, the 1000 series cars, would hold when stopped on hills.
Whether regenerative braking will work on electric lines depends on how the traction power is created. Under certain conditions regenerative braking power can be fed back into the power company grid when there is no or minimal load on the traction power buss. However if DC traction power is generated with a mercury arc or solid state rectifier, power cannot be fed back into the power company grid with existing equipment.
Early electrification, such as New Haven or Pennsylvania RR, used lower frequency AC for traction power at 25 Hz so feeding back into 60 Hz power company lines would have been difficult. The lower frequency AC was used because of inductance problems with early design AC motors.
