Smart UPS Questions/Concerns

[BillP]

Awhile back, our DC experienced a power spike and it left a number of our UPS's with the AVR Trim light activated due to the UPS thinking it had to compensate for high voltages. We had the electrician come in more than once to double check what our incoming voltage was only to find that it was between 124-125V. Each UPS has it's High-Transfer Voltage set to 127 and the Low set to 106.

I used the PowerChute software to change the High-Transfer Voltage setting to 130 instead and that cleared the LED light for AVR Trim. Is it okay to leave the value for High-Transfer Voltage set at 130 for a SmartUPS 1500? Will it have any effects on the hardware that we should be aware of?

The one thing I have noticed is that the Output Voltage for the UPS's with the AVR Trim light is usually around 110 - 112 V and the okay UPS's have theirs set closer to the Input Voltage which is usually any where from 120 - 126 V.

So my 2 questions are:
(1) Will leaving the High-Transfer Voltage setting at 130 effect the UPS's hardware in any way during another possible spike or just in general over time?

(2) Why is the AVR Trim light still activated even the Incoming voltage is still below the 127 setting on these UPSs? Would resetting the UPS back to factory defaults help clear this up?

Let me know if you need more information or clarification on whats explained above. Thanks.

Brock

[voidstar_apc]

>
So my 2 questions are:
(1) Will leaving the High-Transfer Voltage setting at 130 effect the UPS's hardware in any way during another possible spike or just in general over time?
>

The UPS should be fine. The transfer settings need to be set based on what your equipment will tolerate. The initial settings assumes sensitive equipment, however the typical PC power supply tolerates a wide range of input voltages. You can check the label on the PC.

>
(2) Why is the AVR Trim light still activated even the Incoming voltage is still below the 127 setting on these UPSs? Would resetting the UPS back to factory defaults help clear this up?
>

One thing to keep in mind is that there's a hysteresis band. Exceeding 127V put the UPS into trim, but the voltage needs to go well below 127V to get out of trim. This is so the UPS doesn't constantly transfer in and out of trim when the input voltage is at the threshold.

If your equipment is fine with a higher voltage, then setting the threshold higher is the way to go. Otherwise if you want to force it out of trim, you could temporarily raise the threshold and then drop it back down to 127V.

[BillP · Accepted solution]

You may also want to check this Kbase for the default voltage transfer points to have an idea when the UPS should use its AVR trim function or when should it go back Online.

http://nam-en.apc.com/app/answers/detail/a_id/715/kw/715