3 ms·

> If it expects a real grid-like sine wave and doesn't see one it will reject it, regardless if the load would like it or not. But why would it require grid-li

by nuker 2y ago

> If it expects a real grid-like sine wave and doesn't see one it will reject it, regardless if the load would like it or not. But why would it require grid-like sine wave and not go along with whatever is the source, provided source can still be used to charge its batteries? I saw no answers yet, and this "why" is the very key to the discussion.

deleted 2y ago
[deleted]
soneil 2y ago
There's a lot of compromise in UPS design. For example, a common topology in offline UPS is that the inverter and the charger are the same circuit driven differently[0] - so you can't charge the battery while the inverter is carrying load. This is popular at the low-end because you have literally half as much UPS, but makes what you're describing impossible. Another common issue at the low end is that the inverter isn't thermally sized to run non-stop, they know they can cut a corner because your battery presents a finite and known duty cycle. There are ways around this, but at some point you end up fixing the wrong problem - eg, it's cheaper, safer, and more resilient to buy a transfer switch instead of uprating two UPS to be capable of daisy-chaining. [0] https://patents.google.com/patent/US5302858A/en https://patents.google.com/patent/US5302858A/en
numpad0 2y ago
I think you're being gatekept. It's inconceivable that just no one knows why square and triangular waves don't pass as AC.
- nuker 2y ago
  I cannot tell without /s, but yes, who designs like this, lol
  - numpad0 2y ago
    It's not sarcasm. When nobody tells you a why item and you think that's because literally everyone else is dumber than you, it's likely there are odd numbers of sign errors in your heuristics.