Maxim Integrated 71M6534 Energy Meter IC Family Software - Manual (Page 81)

71M653X Software User’s Guide
Get Wh (wxsum) and VARh (varxsum) from CE:
w0sum, w1sum (element Wh for one accumulation interval),
var0sum, var1sum (element VARhs are from CE.
va0sum = sqrt(w0sum 2 + var0sum 2 )
va1sum = sqrt(w0sum 2 + var0sum 2 )
endif
va0sum, va1sum, w0sum, w1sum, var0sum, var1sum are now available.
Figure current, the best available way:
If Irms_A < noise-floor of current measurement && Vrms_A > 0
Irms_A = va0sum/Vrms_A
If Irms_N < noise-floor of current measurement && Vrms_A > 0
Irms_B = va1sum/Vrms_A
Do the creep calculation:
If (Vrms_A < Vthreshold)
creep mode, set element A and B’s voltage, current and watts to zero
else
if (Irms_A < Ithreshold)
creep mode: set element A’s current and watts to zero
if (Irms_B < Ithreshold)
creep mode: set element B’s current and watts to zero
Set the pulse outputs.
Sum positive values to normal registers, negative values to export registers.
5.14.1.17 6534: Calculation of VA*IA+VB*IB+VC*IC Option, Equation 5
The global flow of Wh calculation is an important optimization, and will be selected by compile flag:
Vrms_A = sqrt(v0sqsum) from the CE.
Irms_A = sqrt(i0sqsum) from the CE.
etc. for B and C
Volts and Current are now available for all elements.
Figure Wh, VARh and VAh for this accumulation interval:
If Vrms_A < Vthreshold (i.e. there’s no voltage, probably tampering)
Figure watts with a default voltage, but don’t lie about sensed voltage:
Vrms_A = 0
if abs(Irms_A) > IThreshold,
va0sum = Irms_A * defaultV
w0sum = va0sum
else
set them to zero
varh0 = 0
else
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