| 摘要 |
PURPOSE:To enable to completely protect all rotating zones of the DC motor by a method wherein an instantaneous current detecting value is reduced based on the function of revolution speed in the case where the revolution speed of the motor is in excess of the base speed. CONSTITUTION:The instantaneous current detecting circuit 4' generates the base value of a fixed voltage when the revolution speed is below the base speed and it generates the base value of the voltage in reverse proportion to the revolution speed when the speed is increased to the base speed or more by inputting the arature current signal of the DC motor 1, outputted from a current detecting shunt 2 and a pilot generator 7, and a revolution speed signal and it generates an output when the armature current signal exceeds the base value. An anti- time limit current detecting circuit 5 generates an output with the lag time in inverse proportion to the above value when the armature current detrcting signal exceeds the prescribed value. An output signal circui 6 emits an output when the output of the intantaneous current detecting circuit 4 and the output of the anti- time limit current detecting circuit 5 are applied, and a circuit breaker is energized. |
