17 Common Issues and Troubleshooting Methods for UPS Power Supply Units

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17 Common Issues and Troubleshooting Methods for UPS Power Supply Units

Problem: Bypass light, overload light, and fault light are on.

Possible Cause: Too many devices connected to the UPS power supply.

Solution: Disconnect all non-essential devices. Restart by pressing the ON button and check if the UPS operates normally.

Possible Cause: External dynamic overload.

Solution: Wait until the overload condition disappears. You may need to press the ON button to restart the UPS.

Problem: Fault light is on, overload light is on, bypass light is off.

Possible Cause: Overload.

Solution: Disconnect all non-essential devices. Press the OFF button and then press the ON button to restore power.

Problem: Fault light is on, overload light is off.

Possible Cause: Internal fault in the UPS.

Solution: Do not attempt to use the UPS. Turn off the UPS and immediately proceed with repairs.

Problem: Replace Battery light is on.

Possible Cause: Insufficient battery power.

Solution: Check the battery condition and perform a recovery charge for at least 24 hours. If the problem persists after charging, the battery may need to be replaced.

Possible Cause: Improper battery connection.

Solution: Check all battery connectors for secure connections and signs of oxidation.

Problem: Occasional alarm from the UPS.

Possible Cause: The UPS is operating normally.

Solution: No action required. The UPS is protecting the connected devices.

Problem: UPS fails to provide expected backup time.

Possible Cause: Recent power outages or battery nearing end of life, resulting in insufficient battery power.

Solution: Charge the batteries. After a prolonged power outage, the batteries should be recharged. If the batteries are frequently used or operate in high temperatures, it can accelerate battery capacity depletion. Consider battery replacement if the battery pack has been in use for 3-5 years.

Problem: Front panel indicator lights flash in sequence.

Possible Cause: UPS was remotely shut down or shut down through APC management software. No action required. The UPS will automatically restart when utility power is restored or can be manually restarted by pressing the ON button.

Problem: UPS fails to start.

Possible Cause: Failure to press the ON button.

Solution: Press the ON button to supply power to the UPS and devices.

Possible Cause: UPS not connected to utility power.

Solution: Check the cables or plugs connecting the UPS to utility power for secure connections.

Possible Cause: Input circuit breaker of the UPS has tripped.

Solution: Reduce the UPS load by disconnecting devices and reset the circuit breaker (located at the back of the UPS) by pressing the button. Check if there is a residual current device (RCD) connected to the input circuit breaker and test if it still trips after removing the RCD. Also, check the utility power voltage for being too low or zero by connecting a desk lamp to the utility outlet and observing if the light is dim or flickering.

Possible Cause: Improper external battery connection.

Solution: Check if the battery connectors are securely connected.

Problem: UPS is powered by the battery even though there is normal input voltage.

Possible Cause: Input circuit breaker of the UPS has tripped.

Solution: Reduce the UPS load by disconnecting devices and reset the circuit breaker (located at the back of the UPS) by pressing the button. Check if there is an RCD connected to the input circuit breaker and test if it still trips after removing the RCD.

Possible Cause: High or low line voltage or voltage distortion. Using low-quality gasoline or diesel generators can cause severe voltage distortion to the UPS input voltage.

Solution: Connect the UPS to a different power outlet on a different circuit and restart to check if the UPS operates normally. Use a power analyzer or oscilloscope to test the input voltage and

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