I'm new to this but want to ask this question

  1. If i'm having a 3 phase inverter with a battery backup system. does it requires it to sync with the utility power? if yes how long that sync can take or it doesn't requires any sync as its converting dc to ac

kindly explain to me thanks

Frequency Stability ±0.1% (within 90 seconds/day if the sine wave is used for timing) At this link what this term means

  • \$\begingroup\$ Here's my question - do YOU require it to sync to the utility power? \$\endgroup\$
    – Andy aka
    Commented Sep 21, 2015 at 18:38
  • \$\begingroup\$ my question is if battery is providing the dc when we convert to AC does it needs to have sync period like generators have \$\endgroup\$ Commented Sep 21, 2015 at 19:27
  • \$\begingroup\$ It's only going to need sync if it's going to feed power into the grid. If it's standalone, then it's not an issue. Grid tie inverters (i.e. ones that synchronise with - and feed power to - the grid) synchronise almost instantaneously. If you need precise frequency stability without a direct connection to the grid, well... you're out of luck with most commercial units unless you design your own. \$\endgroup\$
    – Sam
    Commented May 24, 2016 at 11:03

1 Answer 1


Yes, converters in power injection mode do sync with the grid, as they have what is called a Phase-locked loop.

However, it is almost instantaneous compared to a rotating generator (synchronous or induction) in the sense that there is no mass/inertia to accelerate and synchronize with the grid.

  • 1
    \$\begingroup\$ Just a comment though - if your battery system is in backup mode (that is, by definition, operating without grid), then it doesn't need to do any sync as there isn't any grid to sync to in the first place - and the frequency and voltage are established also way faster than a generator, as there is no acceleration. \$\endgroup\$
    – SuperGeo
    Commented Sep 21, 2015 at 22:13

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