Connecting the braking resistor to the DC link

In principle, there are two ways of discharging an energy storage unit of type MDC90A-0120-.. using a braking resistor. The discharge resistor can either be connected to the brake chopper of the MDP92A power supply module or directly to the DC link via a suitable DC contactor. The advantage offered by the connection to the DC link is that a discharge can also take place if the brake chopper is not available due to a device defect or if there is no supply voltage. Proceed as follows to perform a discharge process.

  1. Make sure that all axes and power supply modules of the system are in output stage inhibit. The power supply module with controlled DC link must be set to FCB 51 "Output stage inhibit". Any DC/DC converters that are used to supply the system with external energy (DC grids, etc.) must also be set to FCB 51 "Output stage inhibit".
    • No further energy can flow into and out of the system as a result.
  2. Discharge the energy storage units by connecting the braking resistor to the DC link.
  3. When the discharge process is complete, measure the residual voltage of the DC link (+UZ against -UZ).
  4. If the DC link voltage is less than 3 V, disconnect the system from the AC/DC grid. Make sure that you disconnect all relevant connections.
  5. Measure whether the relevant points are actually de-energized (all poles and against PE).
  6. Make sure that all of the connections opened in step 4 cannot be reconnected unintentionally.
  7. Short-circuit the energy storage units. When doing so, observe the specifications in chapter Short-circuiting energy modules.