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

to SA4102A) at the nominal rated mains voltage. Please note

that this input will saturate with currents bigger than

capability. This also ensures that the device will not saturate

with a 10% variance in mains voltage. The main voltage is

This voltage is fed to a 1MW resistor (R8) to realize the

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)

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sames

PM4100APD

2/14

http://www.sames.co.za

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

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.

Figure 2: Voltage divider circuit

RA

R5

R6

R7

R10

R8

R9

RB

P1

J2

NEUTRAL

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J26

C1