ANALOG INPUT

The PM2102DPD module connects directly to Live and Neutral

supply lines by means of a Molex connector (SCK1), and the

current is measured by using a shunt on the module. The live

is connected to the left terminal of the shunt and live out to the

right (as seen in Fig 2 below). The module is setup for a 80A,

220V shunt sensing application using a 625µ

shunt.

W

sames

PM2102DPD

2/16

http://www.sames.co.za

PRELIMINARY

Table 1: External connector descriptions

Name Function Description

Optional Stepper motor connector. (Remove

jumper J6 to disconnect impulse counter)

Mains connector for module power and voltage

sense

Optional current transformer connector.

(Underneath shunt resistor)

SCK1

JP2

JP3

Figure 2: Current and mains voltage connection diagram

Please take note that the module is referenced to live, and

care must be taken when connecting non-isolated test

equipment to the module.

As an option a stepper motor counter can be directly

connected to JP3 and JP2 is used to connect a CT as current

sensing element.

The resistor values are chosen in such a way that shorting

jumper J16 halfs the voltage on the voltage divider output. This

feature makes the module compatible for both 220V and 110V

supply networks.

Ignoring jumper J16 the values of RA and RB can be calculated

as follows:

RA = R1 + R2 + R3 + R15

RB = R12 || (R11 + 0.5P1)

The center position of P1 is used in the equation to ensure that

calibration can be done by adjusting P1 to a higher or lower

value.

Combining the two equations gives:

(RA + RB) / 220V = RB / 14V

Values for resistors were selected as R10 = 47 , R11 = 22k ,

P1 = 10k

and R12 = 1M .

Substituting the values result in:

RB = 26.29k

RA = RB x (220V / 14V -1)

RA = 386.84k

Choosing standard resistor values for R1, R2, R3, R15 and

keeping in mind that J16 must half the output voltage lead to

the following values:

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The selection and positioning of the current and voltage sense

resistors as well as the biasing resistor is very important to

ensure the correct operation of the SA2102D. These resistors

must be of the same type as specified in the parts list to ensure

that temperature effects and noise susceptibility is minimized.

The voltage input of the SA2102D is driven with a current of

14µA

at the nominal rated main voltage. Please note that

this input will saturate with currents bigger than approximately

17µA

or 25µA

, which translates into a 20% overdrive

capability. This also ensures that the device will not saturate

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

divided down via a resistor network (see Figure 3) to 14V. This

voltage is fed to a 1M

resistor (R12) to realize the 14µA

.

VOLTAGE INPUT IVP

RM S

RM S

peak

RM S

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