Issue Description : Event 7801 is displayed in STP50-40.

Cause : Incorrectly installed contact of DC overvoltage protection surge arresters can cause event 7801 on the inverter.

Solution

1. Check whether the DC surge fits tightly in the surge arrester pocket. 

• Note: If the contact is not established accurately, the integrated micro switches wont work correctly. The slightest gap can cause the device to malfunction.
• (1) shows an inaccurately connected module and (2) an accurately connected module.

2. Check all integrated microswitches in the arrester socket as indicated in the picture below:

• This must be considered for both DC overvoltage protection kits: DC_SPD_Kit4-10 (SPDs Type 2) DC_SPD_KIT5_T1T2 (combined SPDs Type1/2)

3. In case the modules are not defective, check the correct fitting of clips.

1. Press the modules into the socket to lock the clips and ensure a tight fit.
2. Follow the instructions for installation of clips as indicated:

• To retrofit the surge protection with locking clips, there are 4 sets available:
• • 116732-00.01: locking clips set of 9 clips for DC_SPD_Kit4-10
  • 116791-00.01: locking clips set of 9 clips for DC_SPD_KIT5_T1T2
  • 116792-00.01: locking clip T2-3+1 set for AC_SPD_KIT1-10  (class II / T2)
  • 116793-00.01: locking clip T1-3+1 set for AC_SPD_KIT2_T1T2  (class I+II / T1T2)

4. Does the event persist?

• Yes - Please contact the SMA Service Line for further investigation
• No -  Proceed with the next step.

5. Clear event 7801 from the drive's memory via the device's interface by 

• Navigating to 'Device Parameters'
• Click on 'Editing the Parameters'
• In the 'Device' (3) Tab go to 'Reset Operating Data' (4) and chose 'reset events' (5) from the drop down menu
• Click 'Save all' (6)

Source : https://my.sma-service.com/s/article/Event-7801-DC-overvoltage-protection-STP50-40?language=en_US