PROBLEM TO BE SOLVED: To automatically stop a grain carrier device by taking up an electric current through an electric current converter and applying a soft filter, computing an electric current change, judging it as no load when the electric current is reduced by specified proportion with an interval for a specified length of time, opening a switch after a specified period of time and stopping rotation of an electric motor, by a control element. ;SOLUTION: A CPU16 which is a control element computes a change of an electric current value taken up by an electric current converter 11, applies a soft filter, produces an average value of 100 times of a data sampled for each 500 us as avariable variable X (n), processes it every two seconds, and in the case when a variable X (n-1) two seconds before and the data of the current variable X (n) are compared with each other and it is reduced by 4%, it judges it as no load. Thereafter, rotation of an electric motor 2 is stopped by starting a residual process timer, opening a magnet switch 14 as a switch and making it as time-up in fifteen seconds. Consequently, it does not malfunction due to a small electric current change while driving, and it is possible to certainly stop the electric motor 2.;COPYRIGHT: (C)1999,JPO
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