| 摘要 |
<p>PURPOSE:To ensure detection of detachment from lines without being affected by the supply voltage fluctuation, by providing a detachment decisive means to send out the detachment detection signal when the input current value fluctuates more than a predetermined value where the input current flows into a motor to run electric rolling stocks supplied from a current collector. CONSTITUTION:When a pantograph is found off the line, the value of the input current Ii is reduced. The decrease of this input current Ii is detected by a current detector 30 and sent to a sample and hold circuit 32. As this sample and hold circuit 32 samples and holds the value of the input current Ii in every definite period, deviation signals are outputted from a deviation device 33 in proportion to the fluctuating quantity in an instant of the input current Ii. A comparator 34 sends out detachment judgement signals to a multivibrator 35, if the deviation signal has a value larger than the detachment set value. Thus, a detachment detection signal Q is sent out which stops the action of a main chopper 8 for a predetermined period only.</p> |
