Electromagnetic brake operation
What is an electromagnetic brake?
Some stepper motors have an EM brake built-in. In operation, stepper motors maintain a holding torque even when stopped. However, if power is lost, then that torque is lost and any suspended load will move or drop.
The brake is a device to lock the shaft when power is lost--or when commanded--and releases when power is regained--or when commanded. This device is especially necessary in situations of vertically suspended loads.
The response timing of electromagnetic brake
The EM brake locks the axis when the power to the brake is lost. However, this mechanism is not instant and requires a slight amount of time to engage. This means there must be a duration of time in which the brake and the motor are both engaged.
This transition duration, as it is called, does not affect how long it takes for the brake to engage. This duration instead affects how long to wait before releasing or engaging the motor after the brake. The initial value of this overlap time is set to 100ms in the STEP400. It can also be configured using the command
/setBrakeTransitionDuration or from the config tool.
Some exsamples for motors with electromagnetic brake