Datasheet

STPM01 calibration STPM01
52/60 Doc ID 10853 Rev 8
V
DIV
= (X
V
* V
BG
)/ (2 * G
DIF
* A
V
* Kv * G
DF
* G
INT
* B
V
)= 145,6 mV
Choosing R2 = 500 Ω (connected between V
I
and V
SS
), the R1 resistor (connected between
V
LINE
and V
IP
) value is obtained:
R1 = R2 * (Vn - V
DIV
) / V
DIV
= 789,3 Ω
Indicating with I
A
and V
A
the real readings on the STPM01 RMS registers of voltage and
current, and with X
I
and X
V
ideal values of RMS current and voltage readings already
calculated, the final values for calibrators can be calculated as:
X
V
= (Kv * V
A
) / 0.875
X
I
= (Ki * I
A
) / 0.875
If the computed final calibration data would fall out of calibration data range, the energy
meter should be recognized as bad or the given presumptions and calculations above
should be checked. Otherwise, if the final data of calibrators would be written into energy
meter, the RMS readings should be very close to target values I and V and the frequency of
LED output should be very close to target value f.