APC have been bought over by Schneider.
Correct!
And, that's the point where the famous APC UPS workhorses begun to pant and puff...
There still are three kinds of (affordable) APC UPS families:
1. The '
Back' family of line interactive units (see: AVR) with a lousy (multi-level, perhaps? --not sure) 50/60 Hz
stepped sinewave converter unit inside,
2. The '
Smart' family of line interactive units (see: AVR) with a low frequency (iron) power transformer being driven by a 15-25 kHz PWM, either for battery charging or for a (>3% distortion) sinewave output when on battery power, and
3. The '
Smart RT' double-conversion family of <1% distortion sinewave output (continuously), full of high frequency ferritic DC-DC converters and a high voltage DC-AC inverter with a considerably large LC filter at the output stage.
A 3kVA APC Smart (not -RT) UPS hardware discovery and topology can be found here:
and
The best UPS I have ever had (and still have in use) is a Smart RT (1kVA [initially!
], 2002 built), with a 2kVA power board. Since I have it reverse engineered (how could I not have, really?
), this is what exists inside:
- A (~3kVA) wide-input Line PFC booster to the internal VBus of +/- 400 VDC, based on two capacitor banks of 1000uF/450V each,
- A half-bridge AC inverter of VBus to 230VAC true sinewave output,
- An isolated (~2.5kVA) push-pull battery booster (of 4 x 12V/9Ah in series batteries) to VBus, when the mains line is inadequate or absent,
- An isolated 100W half-bridge flyback battery charger, being powered by the VBus, and
- A (<25W) multiple output isolated flyback being powered by the 48V battery bank for the Control Board and the MOSFET/IGBT driver and the input/output signals stages.
In my opinion, if you are depended on AC generators power during mains shortages you should choose nothing less than a double-conversion UPS if you value your protected machinery and your UPS investment.
-George
<EDIT>: Attachment added