Brand: AEG
Category: Power Supply
Document Type: Manual
Language: EN
Manual for Protect 5.31/xxx-480-220-120
Uploaded: April 20, 2026, 7:49 p.m.
Manual Publish Date: 2007
Warranty Information
Warranty obligations are applicable if operating instructions are observed. Spare parts not supplied by AEG may void liability.
The UPS provides an uninterruptible power supply by converting AC voltage to DC voltage for the battery and then converting this DC voltage back to a stable AC voltage for the load. It operates in four modes: mains power supply, faulty mains supply, defective inverter, and manual bypass. The rectifier stabilizes incoming AC to DC for battery charging, while the inverter converts this DC back to AC for the load. In case of mains failure, the battery takes over seamlessly. The static bypass switch (SBS) ensures continuous supply during inverter faults or manual bypass operations.
Troubleshooting and error codes
| Fault | Possible cause | Remedy |
|---|---|---|
| Q1 triggered. | Earth fault or short circuit on the battery side. | Repair the system (renew defective fuse) and restart. If Q1 triggers again, contact AEG service. |
| REC does not work. | Q1 not in "ON" position. F20 to F22 defective. F31 to F33 defective. | Switch on Q1. Replace faulty fuses. Check the SBS circuit. |
| SBS does not work. | Fault in the SBS circuit. | Check the SBS circuit. |
| INV does not work. | F13 to F16 faulty. INV is not switched on. F26 and F27 faulty and/or F17 to F18 faulty. | Replace faulty fuses. Switch on the INV with S1 on DOU. Replace faulty fuses. |
| No load voltage. | Battery voltage is outside the tolerance range. Load fuse faulty. | Check whether Q1 is in the "ON" position. Check voltage at X2. Measure output voltage at X3. Check external load fuses. |
| Faulty connection to battery. | Battery isolator (external) in the "OFF" position. F24 to F25 faulty. | Switch on battery isolator (refer to start-up), renew defective fuses. |
| Fan does not work. | Fan fuse faulty. Loose contact in the plug connection. Fan faulty. | Renew the respective fuse. Unlock and relock the fan connector. Renew the fan. |
| UPS overload. | Load consumption too high. | Reduce the load. |