Hope this is the correct place for my question. I have been using APC UPS units now for 15 years at least but the best I had was 2200 Smart UPS, line interactive. Now I went to look for a double-conversion UPS and found there are actually a lot of different manufactures. I did not know there are DELTA UPS units: RT Series 5/6/8/10/15/20 kVA (new) - DELTA These ones are 650€ or so for 5kVA unit with online double-conversion. APC costs 1800€ at least for this. The question is, did anyone here use or is using Delta UPS units (these or older) and how do they perform?