| 摘要 |
<p>PURPOSE:To enable to use a stainless material to a main resistance only by adding a comparative simple device by a method wherein a portion of a main resistance is made short in the case a terminal voltage of a chopper device detected by the specific timing is more than the set point. CONSTITUTION:The chopper gate control circuit 5 sends the gate control signal Pch(e) to the chopper device 2, the off pulse synchronizing signal SS to the timing circuit 6. In the circuit 6, the pulse Pt(d) with the prescribed time interval tp is sent to a voltage detector 7 from the signal SS after the prescribed time limit td and the instantaneous Value Vd is sent to the terminal voltage Vch at the chopper device at the moment of the said pulse Pt is output, the circuit 8 compares this voltage with the prescribed value in advance and the output make operate the contactor 4 through the contactor or control circuit 9. And while the chopper operation signal Sch is induced from the chopper gate control circuit 5, make maintain the operator condition and compensate the increase of resistance value by the temperature rise of the resistance 3.</p> |
