ADE7978 datasheet(116/120 Pages) AD

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ADE7978/ADE7933/ADE7932

Data Sheet

Rev. 0 | Page 116 of 120

Table 56. CONSEL[1:0] Bits in Energy Registers1

Energy Registers

CONSEL[1:0] = 00

CONSEL[1:0] = 01

CONSEL[1:0] = 11

AWATTHR, AFWATTHR

VA × IA

BWATTHR, BFWATTHR

VB × IB

VB = VA − VC

VB = −VA

VB × IB1

VB × IB

CWATTHR, CFWATTHR

VC × IC

AVARHR, AFVARHR

VA × IA’

BVARHR, BFVARHR

VB × IB’

VB = VA − VC

VB = −VA

VB × IB’1

VB × IB’

CVARHR, CFVARHR

VC × IC’

AVAHR

VA rms × IA rms

BVAHR

VB rms × IB rms

VB rms × IB rms1

VB rms × IB rms

VB = VA − VC

VB = −VA

CVAHR

VC rms × IC rms

In a 3-phase, 3-wire configuration (CONSEL[1:0] = 01), the ADE7978 computes the rms value of the line voltage between Phase A and Phase C and stores the result in

the BVRMS register (see the Voltage RMS in Delta Configurations section). The Phase B current value provided after the HPF is 0. Consequently, the powers associated with

Phase B are 0. To avoid any errors in the frequency output pins (CF1, CF2, or CF3) related to the powers associated with Phase B, disable the contribution of Phase B

to the energy-to-frequency converters by setting the TERMSEL1[1], TERMSEL2[1], or TERMSEL3[1] bit to 0 in the COMPMODE register. For more information, see the

Energy-to-Frequency Conversion section.

Table 57. LCYCMODE Register (Address 0xE702)

Bits

Bit Name

Default Value

Description

LWATT

0: the watthour accumulation registers (AWATTHR, BWATTHR, CWATTHR, AFWATTHR,

BFWATTHR, and CFWATTHR) are configured for regular accumulation mode.

1: the watthour accumulation registers (AWATTHR, BWATTHR, CWATTHR, AFWATTHR,

BFWATTHR, and CFWATTHR) are configured for line cycle accumulation mode.

LVAR

0: the var-hour accumulation registers (AVARHR, BVARHR, CVARHR, AFVARHR, BFVARHR,

and CFVARHR) are configured for regular accumulation mode.

1: the var-hour accumulation registers (AVARHR, BVARHR, CVARHR, AFVARHR, BFVARHR,

and CFVARHR) are configured for line cycle accumulation mode.

LVA

0: the VA-hour accumulation registers (AVAHR, BVAHR, and CVAHR) are configured for

regular accumulation mode.

1: the VA-hour accumulation registers (AVAHR, BVAHR, and CVAHR) are configured for line

cycle accumulation mode.

ZXSEL[0]

0: Phase A is not selected for zero-crossing counts in line cycle accumulation mode.

1: Phase A is selected for zero-crossing counts in line cycle accumulation mode. If more

than one phase is selected for zero-crossing detection, the accumulation time is shortened

accordingly.

ZXSEL[1]

0: Phase B is not selected for zero-crossing counts in line cycle accumulation mode.

1: Phase B is selected for zero-crossing counts in line cycle accumulation mode. If more

than one phase is selected for zero-crossing detection, the accumulation time is shortened

accordingly.

ZXSEL[2]

0: Phase C is not selected for zero-crossing counts in line cycle accumulation mode.

1: Phase C is selected for zero-crossing counts in line cycle accumulation mode. If more

than one phase is selected for zero-crossing detection, the accumulation time is shortened

accordingly.

RSTREAD

0: disables read with reset of all xWATTHR, xVARHR, xVAHR, xFWATTHR, and xFVARHR

registers. Clear this bit to 0 when Bits[2:0] (LVA, LVAR, and LWATT) are set to 1.

1: enables read with reset of all xWATTHR, xVARHR, xVAHR, xFWATTHR, and xFVARHR

registers. When this bit is set to 1, a read of these registers resets them to 0.

PFMODE

0: power factor calculation uses instantaneous values of various phase powers used in its

expression.

1: power factor calculation uses phase energy values calculated using line cycle accumula-

tion mode. The LWATT and LVA bits (Bit 0 and Bit 2) must be enabled for the power factors

to be computed correctly. The update rate of the power factor measurement is the integral

number of half line cycles that is programmed in the LINECYC register.

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