This was a recent issue which popped out during our recurrent training: by checking the AC Standby Pwr voltage and current, what you're actually doing is reading the output of Transfer bus 1, since Standby AC is paralleled with XFER1.
The only way to really check if AC stdby would be available, in case of AC power loss, is making sure the static inverter is working normally, through the INV volts¤t output.
Just 2 pennies
