PM4100APD
sames
The center position of P1 is used in the equation to ensure that
calibration can be done by adjusting P1 to be higher or lower.
Combining the two equations gives:
(RA + RB)/220V = RB/14V
ANALOG INPUT
The most important external components for any SAMES
integrated circuit are the current and voltage sense resistors, as
well as the bias setting resistors. These resistors must be of the
same type as specified in the parts list to ensure that
temperature effects and noise susceptibility is minimized.
VOLTAGE INPUT IVP
The voltage input is driven with a current of 14µA
RMS
(11µA
RMS
to SA4102A) at the nominal rated mains voltage. Please note
that this input will saturate with currents bigger than
approximately 17µA
RMS
, which translates into a 20% overdrive
capability. This also ensures that the device will not saturate
with a 10% variance in mains voltage. The main voltage is
divided down via a resistor network (see Figure 2) to 14V
RMS
.
This voltage is fed to a 1MW resistor (R8) to realize the
14µA
RMS
.
The resistor values are chosen in such a way that shorting
jumper J2 leads to half the voltage on the voltage divider output.
This feature makes the module compatible for both 220V and
110V supply networks.
Ignoring jumper J2 results in the following equations:
RA = R5 + R6 + R7 + R10
RB = R8 || (R9 + 0.5P1)
Values for resistors R9 = 12kW, P1 = 20kW and R8 = 1MW is
chosen.
Substituting the values result in:
RB = 26.29kW
RA = RB x (220V/14V-1)
RA = 386.84kW
Choosing standard resistor values for R5, R6, R7, R10 and
keeping in mind that J2 must half the output voltage leads to the
following values:
R5 = R7 = 82kW
R6 = R10 = 100kW.
RA
J2
J26
NEUTRAL
R5
R6
R7
R10
R9
C1
R8
RB
P1
LIVE IN
Figure 2: Voltage divider circuit
2/14
SAMES [ SAMES ]
