Fast digital calibration procedure

AN2299

16/26

Rev2

In this case the type of current sensor and its nominal value of sensitivity must be known, for

example:

–

following target values can be calculated:

Target RMS reading for given In:

Target RMS reading for given Vn:

Voltage divider output:

From which R1 resistor value is obtained:

●

Rogowski coil - Constant R1

As previously mentioned, voltage divider sensitivity is fixed, thus resistor values R1 and R2

are known, for example:

–Resistor R1=R1

–Resistor R2=R2

following target values can be calculated:

Voltage divider output:

Target RMS reading for given Vn:

Target RMS reading for given In:

X

I

In

K

S

•

A

I

•

Ki

•

G

IN T

•

G

DF

•

G

DIF

B

I

•

•

•

--------------------------------------------------------------------------------------------------------

=

Eq. 17

X

V

fB

V

•

B

I

•

D

UD

•

f

M

X

I

•

------------------------------------------

=

Eq. 18

X

V

V

BG

•

2G

DIF

•

A

V

•

Kv

•

G

DF

G

INT

B

V

•

•

•

----------------------------------------------------------------------------------------------

=

Eq. 19

R1

R2

Vn

V

DI V

–

V

DIV

-------------------------

•

=

[

Ω]

Eq. 20

+

---------------------

•

=

Eq. 21

X

V

V

DIV

V

BG

------------

A

V

Kv

•

G

DF

•

•

B

V

•

=

Eq. 22

X

I

fB

V

•

B

I

•

D

UD

•

•

------------------------------------------

=

Eq. 23