Smart UPS AVR boost/trim thresholds.

[BillP]

This question was originally posted by Vladimir on APC forums on 6/2/2015

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Hello.
The question is - what is voltage levels thresholds for switch to AVR trim/boost and swithc back to live?
Thank You.

[BillP]

This reply was originally posted by Jonathan on APC forums on 6/2/2015

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Hello Vladimir -

May I please know that model number of the UPS that you have? It can be found on the white barcode sticker attached on the back of your UPS.

[BillP]

This reply was originally posted by Vladimir on APC forums on 6/2/2015

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This is the common question, based on suppose that AVR is boosting, for example, if input is "Rated Output Voltage"-5% and higher than "Low Transfer Voltage", and trimming if input is (Rated Output Voltage)+5% and lower than "High Transfer Voltage".

I have number of different Smart UPS, from SURT10000 to SMT750.

Thank You.

[BillP]

This reply was originally posted by Jordan on APC forums on 6/2/2015

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Generally AVR has a +/- 12% range in the Smart UPS, unless your unit features double boost.  This is not true for the SURT series units as they are Online units rather than Line Interactive.

[BillP]

This reply was originally posted by Vladimir on APC forums on 6/2/2015

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So, if the output voltage is set to 230 VAC, boost will be activated at point 230-12%(230)=202.4 VAC, trim will be activated at point 230+12%(230)=257.6.
I suppose i misunderstood You.

[BillP]

This reply was originally posted by Vladimir on APC forums on 6/2/2015

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Sorry my carelessness, from the build-in NMC help:

High Transfer Voltage
The upper limit of acceptable input voltage. When the input reaches this value, the UPS starts to use its AVR Trim feature.
Low Transfer Voltage
The lower limit of acceptable input voltage. When the input reaches this value, the UPS starts to use its AVR Boost feature or switches to battery operation if it does not have this feature.
 
Okay, AVR boost/trim points may be specified obviously, how determine points of switching from AVR to battery.

Thank You.

[voidstar_apc · Accepted solution]

This was originally posted on APC forums on 6/3/2015

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Amount of boost or trim depends on the UPS model, which is why Jonathan asked. Lets assume 12%. V_in = Line Voltage RMS; hyst = hysteresis; => means implication. Treatment of hysteresis is for example only and may be different on an actual UPS.

V_in < Lower Transfer Point/(1+0.12)+hyst => UPS is on battery

Lower Transfer Point/(1+0.12)-hyst < V_in < Lower Transfer Point+hyst => UPS in boost

Lower Transfer Point-hyst < V_in < Upper Transfer Point+hyst => UPS normal

Upper Transfer Point-hyst < V_in < Upper Transfer Point/(1-0.12)+hyst => UPS in trim

Upper Transfer Point/(1-0.12)-hyst < V_in => UPS on battery