1) The Battery is disconnected - SC, SU, and SUA Smart-UPS require a functional battery be connected in order to turn on. If the battery is disconnected, or failed and completely drained, the UPS will not turn on. SMX and SMT series Smart-UPS do not have this limitation.
In Smart-UPS RT units the internal batteries must be connected and capable of supporting a load in order for the UPS to turn on. Each battery in a 208v Smart-UPS RT (10kva or less) must measure more than approximately 85volts and each battery in a 120v Smart-UPS must measure greater than approximately 42volts. Smart-UPS RT units do not charge while in bypass operation and leaving a unit in bypass for extended periods of time can cause batteries to drop below these thresholds. Once batteries have dropped below these points they will need to be replaced.
2) The input breaker is off - Smart-UPS greater than 1500VA have an input breaker which must be in the ON position in order to operate. It is usually located on the rear panel, next to the input power cord. If this breaker is in the OFF position, the UPS will not actually see the input current and will not turn on.
3) There is no Input Power, or it is of poor quality - The UPS will not turn on if the input power is outside of the parameters for online operation. To determine if the issue lies with the input power or with the UPS itself, you can ""Cold Start"" the UPS. This performs a self-test and forces it up on battery power. To perform a cold start:
If the cold start is successful you have determined that the UPS is functional and can operate on battery without issue. You can now plug the UPS into the wall. If it still does not come online you can adjust voltage transfer points and/or sensitivity levels to allow the UPS to function with the available power. On an SU, SUA, or SUM unit this can be accomplished via software or the Network Management Card. On an SMT or SMX unit this can also be performed via the LCD screen. If the input power is of such low quality that you are unable to adjust the UPS to function online you should consult an electrician or your utility provider.
Internal Support Note: Refer to FA239717 when troubleshooting an SURT unit with no signs of life