| 摘要 |
The invention relates to a power screwdriver (10) comprising a motor (12) and a control circuit (22) which switches the motor (12) off by means of a switch-off signal (s_Stop) when it reaches a preset desired torque value (Md _Soll), and a supporting arm (18) which absorbs energy during screwing. The invention is characterized by a voltage limiting circuit (46) that limits th e motor voltage (u_Mot) occurring on the motor (12) when the energy stored i n the supporting arm (18) of the motor (12), which is driven as the generato r and rotates counter to the direction of drive, is dissipated, to a predete rmined limiting voltage (u_Lim). Said limiting voltage (u_Lim) is fixed in s uch a manner that the motor (12) is capable of rotating without counter-torq ue counter to the direction of drive when operated in the generator mode and that yet no inadmissible overvoltages occur.
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