Built-in holding brakes for SIMOTICS S- 1FT7/1FK7 motors
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Built-in holding brakes for SIMOTICS S-1FT7/1FK7 motors
Many drives need a holding brake with an emergency stop function for safety reasons or to meet process requirements.
The permanent-magnet or spring-loaded, single-face brakes used for the 1FT7/1FK7 motors function according to the closed-circuit current principle. The magnetic field of the permanent-magnet exerts a tension on the brake anchor plate, i.e. in a condition of zero current, the brake is closed and the motor shaft thereby stopped. When the rated voltage of 24 V DC ± 10 % is applied to the brake, current flows through the coil and produces a counter-field that cancels the pull of the permanent-magnet, causing the brake to release.
The spring-loaded, single-face brake operates by the force of pressure exerted by the spring instead of a permanent-magnet. In the event of an emergency stop or power outage, approximately 2000 braking operations can be performed with the maximum switched energy without causing excessive wear on the holding brake (condition: maximum external moment of inertia = moment of inertia of motor and nmax type-specific).
The holding brake is not an operational brake.
In order to avoid switching overvoltages and any related effects on the plant environment, the brake cables must be connected externally with a varistor. The connection is made via the power connector or the terminal box.
When connected to the SINAMICS S120 drive system, this overvoltage protection is already included.
