1.1.3 Rogowski Coil

Where (60Hz) is the Rogowski coil scale factor at 60Hz, and it represents the coil sensitivity, measured in millivolts per ampere (mV/A) at 60Hz.

Note: The scale factor KRogowski is defined at the reference frequency fr = 60 Hz because the DI (Digital Integrator) filter was designed for unity gain at 60 Hz. If it is desired to use KRogowski defined at another frequency, the gain of the DI filter must be accounted for in the computation as follows:

Where K_di(f) = 60 Hz/f.

For example, a Rogowski coil is used with an output of 500 uV/A at 60 Hz (or 416.6 uV/A at 50 Hz) and a GPGA = 4, then,

KRogowski(60 Hz) = 1000000 / 500 = 2000

Klx = 2000 / 4 = 500

The metrology firmware uses uQ22.10 to represent both integer and fractional numbers; therefore, the value to set is:

K_lx = ROUND(500 * 2^10) = 0x007D000

Note: The METER_TYPE control register must be configured correctly: 0x00000CCC for CT, 0x00000DDD for SHUNT and 0X00000EEE for Rogowski coil.