AVR and Unit Sensitivity Operation for the BR1000G

[Anonymous user]

I searched the knowledge base and the forums for the exact operation for both of these functions, and haven't found what I was looking for.  Beginning with the Unit Sensitivity function, if the A/C signal input into the UPS is "clean" and "stable" will the unit simple pass that voltage out of the UPS, for Ranges listed under that particular Sensitivity setting?  Secondly, is the AVR  Percentage (+/-11.2%) for both the "Boost" and "Trim" functions applied to every voltage listed in the ranges shown for the Automatic Voltage Regulation in the specifications?

The reason I ask these questions is to understand how the unit will operate under certain circumstances.  When the UPS is adjusted for "Sensitive Loads"/High sensitivity (88-136 Vac), and clean stable power between 88-93 volts is inputted into the UPS, what Voltages will be outputted?

This Voltage range 88-93 Vac, according to the Operators Manual, appears to be outside of the AVR voltage range but still within the Unit Sensitivity voltage range to pass the incoming voltage right through the UPS without AVR or switching to the battery.  The same thing does not seem to exist for the high end of the input Voltage range except when the UPS is adjusted for "Generator Sensitivity"/Low sensitivity.  When the Unit Sensitivity is set to "Default"/Medium or High sensitivity the high voltage limits are 139 Vac and 136 Vac which are lower then the listed high voltage limit of 141 Vac for the Automatic Voltage Regulation.  I take this to mean that all voltages from 126 -141 Vac will be "Trimmed" down and anything above that will cause the UPS the switch to the Battery.

Adjusting the UPS to Low sensitivity creates a gap of one Volt between the high limit of the  sensitivity mode and the AVR.  What happens when the AVR is "Trimming" down the input voltage of 141 Vac and then the input voltage moves up to 142 Vac?

This voltage gap between the AVR and unit Sensitivity exists on the lower end of the voltage range as well.  Looking at the AVR lower limit voltage of 94 Vac, when the AVR is "Boosting" up 94 Vac and then the clean stable input voltage moves down to 93 Vac what voltage is outputted from the UPS?

Thanks for any information on this.

[Anonymous user]

Bump.

[Anonymous user · Accepted solution]

The best information I can offer is based solely on my own personal experience and experimentation. (A variable autotransformer, also called a Variac, is a handy thing to have.)

AVR for those Back-UPS models that have it usually only provides "one step" of adjustment in either direction (high or low voltage). If the line voltage exceeds the range over which AVR can compensate, the unit goes to battery and runs for as long as it can.

I tested a BX1000G (which only has an upward voltage adjustment capability) just now and regardless of the sensitivity setting, its only available AVR mode kicked in at 98-99 volts AC and shut off around 105 volts.

These units are technically considered "standby power supplies" and under normal circumstances, they only pass incoming power to the output (after filtering it, suppressing surges and removing noise of course). If your load requires more protection than these units can offer, APC does have some "dual conversion" models that run their inverters continually and use AC line power only to charge the battery.