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ADE7880

Data Sheet

Rev. A | Page 82 of 104

Table 29. No Load Condition Does Not Function as Defined [er004, Version = 1 Silicon]

Background

Total active power no load uses the total active energy and the apparent energy to trigger the no load condition. If

neither total active energy nor apparent energy are accumulated for a time indicated in the respective APNOLOAD and

VANOLOAD unsigned, 16-bit registers, the no load condition is triggered, the total active energy of that phase is not

accumulated and no CF pulses are generated based on the total active energy.

Fundamental active and reactive powers no load uses the fundamental active and reactive energies to trigger the no load

condition. If neither the fundamental active energy nor the fundamental reactive energy are accumulated for a time

indicated in the respective APNOLOAD and VARNOLOAD unsigned 16-bit registers, the no load condition is triggered, the

fundamental active and reactive energies of that phase are not accumulated, and no CF pulses are generated based on

the fundamental active and reactive energies.

Issue

When the total active energy on Phase x (x = A, B, or C) is lower than APNOLOAD and the apparent energy is above

VANOLOAD, the no load condition should not be triggered. It was observed that although CF pulses continue to be

generated, the Bit 0 (NLOAD) and Bits[2:0] (NLPHASE) in STATUS1 and PHNOLOAD registers continue to be cleared to 0

indicating an out of no load condition, the xWATTHR register stops accumulating energy.

It was observed that the fundamental active energy no load functions independently of the fundamental reactive energy

no load. If, for example, the fundamental active energy is below APNOLOAD and the fundamental reactive energy is

above VARNOLOAD, both energies should continue to accumulate because the phase is out of no load condition. Instead,

the CF pulses, based on the phase fundamental active energy, are not generated and the FWATTHR registers are blocked,

while the CF pulses, based on the fundamental reactive energy, are generated. Thus, the FVARHR registers continue to

accumulate and the Bit 1 (FNLOAD) in the STATUS1 register and Bits[5:3] (FNLPHASE) in the PHNOLOAD register are

cleared to 0.

Workaround

Because both no load conditions use the APNOLOAD threshold, a workaround for both issues is presented as follows:



Clear APNOLOAD and VARNOLOAD to 0.



Set VANOLOAD at desired value.

When the Phase x (x = A, B, or C) apparent energy becomes smaller then VANOLOAD, the Bit 2 (VANLOAD) in STATUS1 is

set to 1, together with one of the Bits[2:0] (VANLPHASE) in PHNOLOAD. Then, set APNOLOAD and VARNOLOAD equal to

VANOLOAD.

The Phase x (x = A, B, or C) total active energy enters no load condition.



CF pulses stop.



Bit 0 (NLOAD) in the STATUS1 register is set to 1.



One of the Bits[2:0], (NLPHASE[2:0]), in the PHNOLOAD register is set to 1.



The xWATTHR register stops accumulating energy.

The Phase x (x = A, B, or C) fundamental active and reactive energies enter no load condition.



CF pulses stop.



Bit 1 (FNLOAD) in the STATUS1 register is set to 1.



One of the Bits[5:3], (FNLPHASE[2:0]), in the PHNOLOAD register is set to 1.



The xFWATTHR and xVARHR registers stop accumulating energy.

Related Issues

None.

SECTION 1. ADE7880 FUNCTIONALITY ISSUES

Reference Number

Description

Status

er001

The LAST_ADD register shows the wrong value for the harmonic calculations registers in SPI mode.

Identified

er002

To obtain the best accuracy performance, the internal setting must be changed.

Identified

er003

The high-pass filter cannot be disabled in the Phase C voltage data path

Identified

er004

The no load condition does not function as defined.

Identified

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