528.2 FaultsPROTECT 1. outputs detailed error messages by means ofwhich you or the service personnel can quickly and accuratelylocalise and interpret any malfunctions that occur. You can findsuggestions for action / solutions in the following to correctproblems using error descriptions according to chapter 8.1.2:8.2.1 Error MessagesMessage / display Cause SolutionNo display, no acousticsignal although systemis connected to themains current supply.Mains and/orbattery voltage notin tolerance range,poss. totallydischarged battery.Check mains connectionagain. Check the back-up fuse and the mainsinput miniature circuitbreaker as well.Mains OK, but UPSdoes not switch tobypassPositionMains inputuse is in “OFF”positionSwitch mains inputminiature circuit breakerto “ON”“Line” LED flashes and“Battery” LED lights upMains voltageand/or mainsfrequency areoutside of toleranceCheck the mains(voltage, frequency)“Inverter" LED and"Battery" LED light up.The acoustic signalsounds every 4 seconds(operating states 7-10).“Inverter" LED and"Battery" LED light up.The acoustic signalsounds every second(operating state no. 6).Mains voltagesupply interrupted.Automaticswitchover tobattery mode.Try to re-establish themains voltage (poss.fuse triggered in thesubdistribution?).Whenthe acoustic signalsounds every second,the battery is almostcompletely discharged.Carry out a systemshutdown of your ITequipment at this pointin time at the latest.“Fault” LED lights up,warning signal soundstwice per second (errordescriptions no. 12/13).Overload of theUPS System.Immediately reduce thecapacity utilisation of theUPS by disconnectingpart of your loads.