How do I configure ADE7880 to correctly calculate energy in 4-wire DELTA, where the Neutral is the actual Neutral, not between phase A and B?

How do I configure ADE7880 to correctly calculate energy in 4-wire DELTA, where the Neutral is the actual Neutral, not between phase A and B?

Hello Dlath,

My configuration is exactly as you have describe it in your first paragraph.

This configuration does not fit any of the four configurations described in the datasheet, as far as I can see. Then my question is:

Can ADE7880 calculate actual energy for this configuration? Is there a way that the internal calculations can be manipulated by the firmware?

Thank you for your help,

Silvo

Hi Silvo,

In that case, there are a variety of different options and it is convenient that you have the Neutral as a connection, as you will see below. Page 14 - 15 of the Application Note, AN-639, may be helpful in visualizing the configurations. Below are two configurations that can be used:

- The meter can be set up as a 4-wire Wye meter, CONSEL = 00, Figure 13 of AN-639. In which case, each phase current would be measured, and each phase to neutral voltage is measured, essentially treating the system as if it was a Wye load. This means that each phase active energy will be accurate for the respective phase and the total active energy (sum of the phase active energies) will be accurate for the overall Delta load.
- The meter can be set up as a 3-wire Delta meter, CONSEL = 01, Figure 15 of AN-639. In which case, phase B would be taken as the reference ground for the ADE7880 and the 2 voltage measurements would be taken with respect to phase B. Then the current on phase A and C would be measured. This means that the total active energy would be accurate by summing the active energy registers, AWATTHR+CWATTHR, phase B isn't included because the current on phase B is not monitored since IB = - IA - IC.

Please let me know if these configurations need clarification.

Regards,

Dlath

Hi Silvo,

Let me see if I understand this correctly:

The connections available to you are the 3 phases (A, B and C) and the Neutral, in total 4 wires. Does this mean that the load is connected in a delta configuration with 3 loads, one between A and B, one between B and C, and one between C and A. Then the source is an actual 4-wire wye source supplying a 3-wire delta load? What is the neutral used for in this case?

With the 3-phase wye configuration that is available, given the 3-phase and a neutral, the system can be treated like a wye system (phase current and phase to neutral voltage measured) and the energy can be calculated per phase and added up for the total for all 3 phases. Or it can be treated like a 3-wire delta measuring phase current and phase B taken as the reference to measure Phase A/C to B voltage.

Regards,

Dlath