| 摘要 |
<p>PURPOSE:To make a speed detector of an electric rolling stock needless by a method wherein the current flowing rate of a chopper is detected to control a circuit- breaker for short-circuiting of a brake resistor. CONSTITUTION:When the current flowing rate in the chopper connected to a shunt circuit of the electric power source becomes to the minimum during power running of the electric rolling stock in accordance with a power running command 6, a contact TON is closed through an interlock 7 being closed only during power running to make an auxiliary relay FAR to ON, and the rolling stock car is driven by weak magnetic field. A relay SR is also made to ON in accordance with ON of a contact FARa, and because the circuit-breaker L to short-circuit the brake resistor is not operated at this time, the relay thereof is made to self-holding by a contact Lb. When a regenerative braking command 4 is outputted next, a value obtained by multiplying the minimum current flowing rate of the chopper by the trolley voltage ec is compared 9 with the differential voltage between the trolley voltage ec and the electric motor voltage eM. When this differential voltage becomes to large, a relay EAR is made to ON to close the circuit-breaker L short-circuiting the brake resistor.</p> |
