ARRANEGEMENT FOR CONTROLLING A DC MACHINE

The invention relates to a method for actuating a DC machine by means of a standard controller and a safety arrangement, wherein the DC current is connected to a supply voltage by means of a main switch (HS) to be activated by a control voltage (Us), and wherein firing pulses for actuating the electronic switch disposed in a DC converter for controlling the rotational speed and/or torque of the DC machine from a firing pulse supply voltage (Vz). For this purpose the safety arrangement is operated as an extension of the standard controller and comprises a safety module (SM), wherein an STO function for the safe torque release of the DC machine is carried out by means of said safety arrangement such that a torque release is initially provided to the standard controller upon initiating the STO function, and that the safety module (SM) does not interrupt the control voltage (Us) via a first shut-off path of the safety arrangement and/or does not interrupt the firing pulse supply voltage (Vz) via a second shut-off path of the safety arrangement until expiration of a predetermined time span after initiation of the STO function.