Question:
According to the documentation, motor brake control with the 24 V brake modules (E94AZH) of the Servo Drives 9400 always requires a separate 24 V supply. What are the reasons for this and what are the effects of a common grounding of the 24 V voltage supply?
Answer:
In the event of an error, a separate supply voltage prevents possible danger to persons.
Explanations:
There is a basic insulation between the brake module and the power stage and between the brake module and the control card.
Between the power stage and the control card there is a double or reinforced basic insulation.
- If an error occurs and a motor phase touches the 24 V of the brake module, there continues to be a basic insulation towards the control card. This requires that different voltage supplies are used for the brake modules and the control electronics supply of the controller.
- If one and the same 24 V supply was used for the brake modules and the control electronics supply of the controller, there could occur a dangerous touch voltage at the connectors of the control card.
Usually, the GND of every 24 V voltage is earthed in the control cabinet. If a motor phase touches the GND of a brake module, this is identified as an earth fault and the controller is switched off.
The described effects are independent of the 24 V voltages being interconnected via the earthing of the GND.
