power Metering with ade7953

Hello, 

I'm trying to understand more about Ade 7953.  I'm reading normally and without problem voltages and active power ( I'm using a load of 7.5 Kw, 220V for test). 

I simply don't understand how to measure current consumption over time,  so basically I would need to understand how accumulation work.  

Can you please me advice on how to approach this ? 

Thanks !

Gio