Error message SD-WR-Bruecke, SD-inv-bridge
(en) The SD-WR bridge error message indicates that the inverter has detected a disturbance in the power electronics. The error can appear sporadically or continuously; the yellow LED flashes code 5. The inverter disconnects itself from the utility grid and then attempts to reconnect itself to the utility grid.
The error can be caused by ground faults and insulation errors in the DC installation, because the inverter bridge in transformerless inverters can be damaged by sporadic ground faults in the module array. For more information and suggested corrective measures, see the Riso diagnostics.
WARNING! Danger to life due to electric shock
In the event of a ground fault, high voltages may be present. Do not touch the cables, the substructure, the frame or the modules of the PV array.
In the event of sporadically occurring disturbances, we recommend having the DC installation checked by an installer for insulation errors, as described in the device’s installation or service manual. It is not necessary to replace the inverter.
If the disturbance continues to occur, however, the inverter must be replaced. In this case, the module array and the DC cabling must also be carefully checked for insulation errors before the replacement inverter is commissioned. This is the only way to rule out further failures.
If the disturbance continues to occur, please contact SMA Service with the following information to order a replacement device:
• Device type and serial number of the inverter
• If the device is in the warranty period: the warranty certificate
• Error message and LED display
• How long has the error been present for? Is it sporadic or continuous?
• Measured DC voltage between +/- and PE of all strings
• Measured insulation resistance of all strings and weather conditions during the measurement
All work on the inverter and the cabling of the PV array must be carried out by an electrically qualified person. SMA accepts no liability for the information and solutions given in the Online Service Center. Additional information can be found in our Online Service Center’s terms and conditions of use.