SMT1500 runs in Green Mode but still consumes 90 watts

[BillP]

Hi,

I've always been extremely happy with APC products in terms of reliability, but I've discovered that both my newer (purchased Sept 2014) SMT 1500 and my older (purchased June 1999) use appoximately 90 watts of power when under no load (UPS plugged in, but nothing plugged into it). It surprises me that the newer SMT1500 says it's running in "Green Mode", but still uses the same power as the older SMT1400. Any thoughts?

Thank you.

Chuck

[voidstar_apc]

"Green mode" bypasses the AVR (boost and trim) transformer. However since you have no load, there's little power lost through the transformer anyways.

For some perspective, take a look at the efficiency graph. At low loads the energy required to power the UPS dominates. At higher loads the ups gets close to 98% efficient which, for a 1000W unit, implies the UPS needs 20W. Not sure why yours needs 90W... maybe the battery was charging? Anyways, the other take-away is properly sizing the UPS so it's at least 30% loaded will make a bigger difference than green mode.

[BillP · Accepted solution]

voidstar, Thank you. This explains my confusion.