ade7854 Analog Devices, Inc., ade7854 Datasheet - Page 26

• Manufacturer Part Number: ade7854
• Description: Poly Phase Multifunction Energy Metering Ic With Neutral Current Measurement
• Manufacturer: Analog Devices, Inc.

ADE7854
used and therefore it is not recommended to use the detection
circuit. In these cases, the time intervals between phase voltages
should be used to analyze the phase sequence (see Time
Interval Between Phases section for details).
Figure 29 presents the case in which phase A voltage is not
followed by phase B voltage, but by phase C voltage. Every time
a negative to positive zero crossing occurs, bit 19 (SEQERR) in
STATUS1[31:0] register is set to 1 because such zero crossings
on phase C, B or A cannot come after zero crossings from phase
A, C or respectively B zero crossings.
Once a phase sequence error has been detected, the time
measurement between various phase voltages (see Time Interval
Between Phases section) may help to identify which phase
voltage should be considered with another phase current in the
computational data path. The bits 9-8 (VTOIA[1:0]), 11-10
(VTOIB[1:0] ) and 13-12 (VTOIC[1:0]) in CONFIG[15:0]
register may be used to direct one phase voltage to the data
path of another phase. See Changing Phase voltage data path
section for details.
Bit 19 (SEQERR) in
Figure 29. SEQERR bit set to 1 when phase A voltage is followed by phase C
STATUS1[31:0]
Voltages after
A,B, C Phase
LPF1
ZX A
Phase A
IRQ
1
Figure 30. Phase Sequence Detection
STATUS1[19] set to 1
ZX A
Phase A
ZX B
Phase B
voltage
ZX C
Phase C
STATUS1[19] cancelled
STATUS1[31:0] with
ZX C
SEQERR bit set
by a write to
ZX B
Phase C
Phase B
Rev. PrC| Page 26 of 71
Time Interval Between Phases
The ADE7854 has the capability to measure the time delay
between phase voltages, between phase currents or between
voltages and currents of the same phase. The negative to
positive transitions identified by the zero crossing detection
circuit are used as start and stop measuring points. Only one set
of such measurements are available at one time, based on bits
10,9 (ANGLESEL[1:0]) in COMPMODE[15:0] register.
When ANGLESEL[1:0] bits are set to 00, the default value, then
the delays between voltages and currents on the same phase are
measured. The delay between phase A voltage and phase A
current is stored in the 16-bit unsigned ANGLE0[15:0] register
(See Figure 31). In a similar way, the delays between voltages
and currents on phase B and C are stored in ANGLE1[15:0] and
ANGLE2[15:0] registers respectively.
When ANGLESEL[1:0] bits are set to 01, the delays between
phase voltages are measured. The delay between phase A
voltage and phase C voltage is stored into ANGLE0[15:0]. The
delay between phase B voltage and phase C voltage is stored in
ANGLE1[15:0] register and the delay between phase A voltage
and phase B voltage is stored into ANGLE2[15:0] register (see
Figure 32).
When ANGLESEL[1:0] bits are set to 10, the delays between
phase currents are measured. Similar to delays between phase
voltages, the delay between phase A and phase C currents is
Figure 31.Delay between phase A voltage and current is stored in
ANGLE2
Figure 32. Delays between phase voltages(currents)
ANGLE0
Phase A
Voltage
Phase A
ANGLE0
Preliminary Technical Data
ANGLE1
ANGLE0[15:0]
Phase A
Phase B
Current
Phase C