ADE9078ACPZ datasheet(54/108 Pages) AD

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Data Sheet

ADE9078

Rev. 0 | Page 53 of 107

Figure 78 shows a phase sequence error for a 4-wire wye or 4-

wire delta due to a wiring or installation error.

ZXA

ZXB

PHASE SEQUENCE ERROR

(SEQERR = 1)

SEQERR

A,B,C

PHASE

VOLTAGES

AFTER

LPF1

ZXC

Figure 78. 4-Wire Wye and 4-Wire Delta Phase Sequence Error (Wiring Error)

Figure 79 shows that in an installation with the normal phase

sequence, a phase sequence error is generated if a phase voltage

drops below the ZXTHRSH value.

ZXC

ZXB

A,B,C

PHASE

VOLTAGES

AFTER

LPF1

PHASE SEQUENCE ERROR

ZXC

ZXB

ZXC

ZXB

SEQERR

ZXA

Figure 79. 4-Wire Wye, 4-Wire Delta Phase Sequence Error from a Phase

Voltage Dropping Below ZXTHRSH with SEQ_CYC = 1

3-Wire Delta

For a 3-wire delta system, VCONSEL = 001 or 100 as described

in the Applications Information section. In a 3-wire delta

system, the ZXVC and ZXVA positive to negative (ZXx_POS)

and negative to positive (ZXx_NEG) transitions are monitored

to detect a phase sequence error. Figure 80 shows the normal

phase sequence for a 3-wire delta with VCONSEL = 001.

ZXA_POS ZXC_NEG

PHASE A

= VAB

PHASE C

= VCB

VA,VC

AFTER LPF1

ZXC_POS

NORMAL PHASE SEQUENCE

SEQERR = 0

ZXA_NEG

Figure 80. 3-Wire Delta Normal Phase Sequence

Write SEQ_CYC to indicate how many consecutive incorrect

transitions must be observed before raising the SEQ_ERR

interrupt. It is recommended to set SEQ_CYC to 1. Figure 81

shows an installation error for 3-wire delta that results in a

detected phase sequence error.

SEQERR

SET TO 1

ZXC_POS ZXA_NEG

PHASE C

= VCB

PHASE A

= VAB

VA, VC

AFTER LPF1

ZXA_POS

ZXC_NEG

Figure 81. 3-Wire Delta Phase Sequence Error (Wiring Error)

Figure 82 shows that in an installation with the normal phase

sequence, a phase sequence error is generated if one of the

phase voltages drops below the ZXTHRSH value.

ZXC_NEG

ZXA_POS

PHASE C PHASE A

VA, VB, VC

AFTER LPF1

ZXA_NEG

SEQERR

ZXA_NEG

ZXA_POS

ZXA_NEG

IRQ1

SEQERR

SET TO 1

WRITE SEQERR = 1

TO ACKNOWLEDGE THIS EVENT

AND CLEAR SEQERR

ZXC_POS

Figure 82. 3-Wire Delta Phase Sequence Error from a Phase Voltage

Dropping Below ZXTHRSH with SEQ_CYC = 1

Peak Detection

The ADE9078 records the peak value measured on the current

and voltage channels, from the xI_PCF and xV_PCF

waveforms. The PEAKSEL bits in the CONFIG3 register allow

the user to select which phases to monitor. Set PEAKSEL, Bit 2

to monitor Phase C; PEAKSEL, Bit 1 for Phase B; and

PEAKSEL, Bit 0 for Phase A. Set PEAKSEL = 111b to monitor

all three phases.

The IPEAK register stores the peak current value in

IPEAKVAL, Bits[23:0] and indicates which phase currents

reached the value in the IPPHASE bits. IPEAKVAL is equal to

xI_PCF/25.

IPPHASE, Bit 2 indicates that Phase C had the peak value;

IPPHASE, Bit 1 indicates Phase B; and IPPHASE, Bit 0 indicates

Phase A.

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