“1480” is the number of samples to average to give you a reading.
When you use calcVI(…) to measure power, it measures a whole number of cycles of mains voltage - because it has a voltage input. This is the best way we have found for accurate results.
You are not using the voltage input, therefore all you can do is guess how many samples your Arduino will measure in a whole number of mains cycles. For you, one cycle is 16.667 ms, and we aim to measure for 200 ms, so 12 cycles.
We have found that the sampling rates, measured with a standard emonTx V3.4 (and the emonPi and Arduino Uno have the same processor) are:
calcIrms( ) - approx 5588 current samples per second.
calcVI( ) - approx 2535 pairs of voltage & current samples per second.
“1480” is out of date - we’ve speeded up the calculations since that was written. The ‘best’ number now is 1118. There’s more information here:
“111.1” is the calibration constant. In numbers, it is the current in the c.t. that gives you 1.0 V at the ADC input. So it depends on the c.t. ratio (100 A : 50 mA) and the burden resistor you’re using (18 Ω).