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sames

sames

PM4100APD

http://www.sames.co.za

CURRENT SENSE INPUT

Resistors R2 and R3 (figure 3 and figure 4) define the current

level into the current sense inputs of the device. The

PM4100APD module can be configured to use any type of

shunt or CT, but to ensure proper current sensing it is advisable

to use a shunt or CT that will give a voltage drop of at least 20mV

at maximum supply current. The resistor values are calculated

conditions. The design equation is as follows:

SHUNT Sensing

L

Figure 4: Current sensing using a CT

Figure 3: Current sensing using a shunt

R2

R3

R1

J1

CT

GND

1

2

3

CON2

CURRENT

IIN

IIP

R2

R3

GND

1

2

3

CON2

CURRENT

IIN

IIP

SENSING METHOD (CT OR SHUNT)

Provision is made for the use of either a Current Transformer

(CT) or a Shunt on the application module. For use with a CT,

the terminating resistor (R1) and phase compensation

capacitor (C1), as well as jumper (J1) must be inserted. The

jumper references one side of the CT to ground for sensing.

When using a CT the current sensing resistors (R2 and R3)

must be inserted according to the equation stated below.

CT Sensing

L

1:2500 = CT ratio

The capacitor C1 is inserted to compensate for the phase shift

caused by the current transformer. The following equation

shows how to calculate the capacitor value for a phase shift of

0.18 degrees.

C = 1 / (2 x p x Mains frequency x R8 x tan(Phase shift angle))

C = 1 / (2 x p x 50 x 1M x tan(0.18 degrees))

C = 1.013µF

CTs with a low phase is recommended.

REFERENCE VOLTAGE

The on chip reference current is determined from a biasing

This is 47kW for the SA2102D and SA4102A, and 24kW for the

rest of the devices compatible with this module.

ANALOG GROUND (GND)

The GND pin of the device is connected to the analog ground