Error light in my apc smart ups sc 1500va ups

1. Four beeps every 30seconds (On Battery LED will be illuminated)
This alarm indicates that the Battery PowerSupplied outlets are now supplying battery power as opposed to power from theutility. If the UPS determines that the input utility power is unsafe for yourcomputer equipment, the UPS will switch to battery power.
Note: Ifthe power disturbance is brief, you may only hear one or two beeps.

2. Continuous Beeping (On Battery LED will beilluminated)
This alarm indicates that a Low Batterycondition has been reached and that the UPS will soon shutdown. Once the UPStransfers to On Battery operation, it can only stay on battery for a limitedamount of time. The UPS will sound this alarm about two minutes before thebatteries are totally exhausted. Once exhausted, the UPS will shutdown and turnoff its output power to your equipment. If you hear this tone you shouldimmediately shutdown your computer to prevent data loss or corruption.

3. Continuous Beeps for 30 seconds (BackUPS OFFICE 250 and 280 ONLY)
This alarm indicates the unit has detected anOverload condition after it has performed a self-test during start-up.

4. Continuous Two-Tone Beep
This alarm indicates a severe Overload wasdetected while the unit was on-battery operation. This tone will continue tosound until the unit shuts down.

5. Continuous Tone (On Battery LED will beflashing)
This alarm indicates that the battery-poweredoutlets are overloaded.

6. Continuous Tone (On Line and On BatteryLEDs flashing) Back UPS OFFICE 350,400, and 500 ONLY
This alarm indicates that an internal UPS faulthas occurred.

Sometimes this ups turn on the fault indicator when is plug to red commercial, in this case i turn on battery mode and then plug to red commercial.