Analog Devices ADE9000 Technical Reference Manual page 28

UG-1098
crossings are used as the reference. The time between the zero-
crossing on Phase A and Phase B is stored in the ANGL_IA_IB
register. The time between the zero-crossing on Phase B and
Phase C is stored in the ANGL_IB_IC register, and the time in
between the zero-crossings on Phase A and Phase C is stored in
the ANGL_IA_IC register.
The voltage to current phase angles are measured as well.
These angles can be used to determine the power factor at the
fundamental. ANGL_VA_IA reflects the phase angle between
the Phase A voltage and current, as shown in Figure 32.
ANGL_VB_IB holds the Phase B voltage to current phase angle,
and ANGL_VC_IC holds the Phase C voltage to current phase
angle.
PHASE A
VOLTAGE
ANGL_VA_IA
Figure 32. Voltage to Current Phase Angles
Note that if the magnitude of the voltage channel is below the
user configured zero-crossing threshold, the zero-crossing
output for that phase is not generated. In this event, the
corresponding ANGLx_x2x measurements are not updated; the
last value remains in the register. The current channel does not
have these thresholds. With a low input signal level, spurious
zero-crossing events may be generated on the current channel,
which results in ANGLx_I2I and ANGLx_V2I readings that are
not meaningful.
Phase Sequence Error Detection
4-Wire Wye and 4-Wire Delta
For 4-wire wye and 4-wire delta meters, the normal phase
sequence is shown in Figure 33.
PHASE A
A,B,C PHASE
VOLTAGES AFTER
LPF1
ZXA
NORMAL PHASE SEQUENCE
Figure 33. 4-Wire Wye and 4-Wire Delta Normal Phase Sequence
PHASE A
CURRENT
PHASE B PHASE C
ZXB ZXC
SEQERR = 0
ADE9000 Technical Reference Manual
For a 4-wire wye or 4-wire delta system, VCONSEL[2:0] is 000,
010, or 011, as described in the Applying the ADE9000 to
Different Metering Configurations section. In these 4-wire
systems, the negative to positive transitions on ZXVA, ZXVB,
and ZXVC are monitored to determine if there is a phase
sequence error, as shown in Figure 35. To detect a phase
sequence error, set how many sequences to observe in the
SEQ_CYC register. It is recommended to set SEQ_CYC to 1.
Figure 34 shows a phase sequence error for a 4-wire wye or 4-
wire delta due to a wiring or installation error.
VOLTAGES
Figure 34. 4-Wire Wye and 4-Wire Delta Phase Sequence Error (Wiring Error)
Figure 35 shows that in an installation with the normal phase
sequence, a phase sequence error is generated if a phase voltage
drops below the ZXTHRSH.
A,B,C
PHASE
VOLTAGES
AFTER
LPF1
ZXA ZXB
SEQERR
Figure 35. 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[2:0] is 001 or 100, as
described in the Applying the ADE9000 to Different Metering
Configurations section. In a 3-wire delta system, the ZXVC and
ZXVA positive to negative and negative to positive transitions
are monitored to detect a phase sequence error. Figure 36 shows
the normal phase sequence for a 3-wire delta with
VCONSEL[2:0] = 001.
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A,B,C
PHASE
AFTER
LPF1
ZXC
ZXB ZXA
SEQERR
PHASE SEQUENCE ERROR
(SEQERR = 1)
ZXC ZXB ZXC
PHASE SEQUENCE ERROR
ZXB ZXC