Isn't that the point of the AVR (assuming your UPS has one, which mine does)? If you supply your machine with constant 120V, wouldn't that still be considered clean energy?
The point of AVR is to regulate voltage - not 'clean' it. 'Clean' is a subjective term for all type of anomalies. A term to confuse laymen who do not demand numbers.
Meanwhile, voltage can drop so low that incandescent bulbs dim to 50% intensity. Ideal power for all electronics (as will be described later).
This is a 120 volt sine wave output UPS. 200 volt square waves with a spike of up to 270 volts between those square waves. The RMS is a regulated 120 VAC. A perfectly ideal power source for all electronics. And potentially destructive to small electric motors and power strip protectors.
Due to 'dirty' power from that UPS in battery backup mode, the manufacturer will quietly recommend no motorized appliances or power strip protectors on its output. And would rather not say why. They are often selling a myth of 'clean' power. If that UPS power was really clean, then the manufacturer defined it with numbers in specification. Good luck finding such numbers such as %THD. Better for profits is to encourage the least informed to keep making subjective recommendations.
Do you need 'clean' UPS power? That "120 volt sine wave output" is perfectly ideal power due to protection already inside all electronics. Then electronics converts that power to even 'dirtier' electricity. First 120 volts is converted to well over 300 volts. Then converted to high voltage radio waves. Then the supply converts all that to a rock steady low voltage DC. Even makes the '50% intensity' voltage irrelevant and ideal. Best 'cleaning' already exists inside electronics. Those educated by advertising would not know this.
Other anomalies also exist. To have a better answer means discussing each anomaly, one at a time, with numbers. Most who recommend a UPS never do that. Most will recommend only what hearsay and sales brochures encourage them to believe.
If anyone makes a recommendation without citing specification numbers, then suspect the worst. This post contains some numeric examples.
OP asked for surge protection. Due to no numbers, he has confused a blackout with a surge. What happens when power is restored? Due to powering so many loads, voltage slowly increases. This may be harmful to motorized appliances that dislike low voltages - ie refrigerator. And that type of power on is ideal for all electronics. Sometimes we design circuits inside electronics to reproduce that slowly increasing voltage to increase life expectancy. It contradicts what so many believe due to "subjective" knowledge.
Spikes during power on are mostly mythical. Sometimes a surge can cause a power off. So surge damage happened before power was lost. Those who 'know' only using observation then assume power on cause the damage. Another example of why so many know only from hearsay and junk science reasoning.
UPS has one primary function. To provide temporary and 'dirty' power during a blackout. Other anomalies are best solved elsewhere.
