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參數(shù)資料
| 型號： | ADE7761ARSRL |
| 廠商： | ANALOG DEVICES INC |
| 元件分類： | 模擬信號調(diào)理 |
| 英文描述： | Energy Metering IC with On-Chip Fault and Missing Neutral Detection |
| 中文描述： | SPECIALTY ANALOG CIRCUIT, PDSO20 |
| 封裝： | MO-150AE, SSOP-20 |
| 文件頁數(shù)： | 20/28頁 |
| 文件大?。?/td> | 302K |
| 代理商： | ADE7761ARSRL |
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ADE7761
Fault with Active Input Greater than Inactive Input
If V
1A
is the active current input (that is, being used for billing),
and the voltage signal on V
1B
(inactive input) falls below 93.75%
of V
1A
, the fault indicator becomes active. Both analog inputs are
filtered and averaged to prevent false triggering of this logic
output. As a consequence of the filtering, there is a time delay of
approximately 3 s on the logic output FAULT after the fault
event. The FAULT logic output is independent of any activity on
outputs F1 or F2. Figure 26 shows one condition under which
FAULT becomes active. Because V
1A
is the active input and it is
still greater than V
1B
, billing is maintained on V
1A
, that is, no
swap to the V
1B
input occurs. V
1A
remains the active input.
Rev. A | Page 20 of 28
V
1B
V
1N
V
1A
AGND
FILTER
AND
COMPARE
TO
MULTIPLIER
FAULT
A
B
V
1A
V
1B
V
1B
< 93.75% OF V
1A
>0
<0
ACTIVE POINT – INACTIVE INPUT
6.25% OF ACTIVE INPUT
0
0V
FAULT
V
1A
V
1B
Figure 26. Fault Conditions for Active Input Greater than Inactive Input
Fault with Inactive Input Greater than Active Input
Figure 27 illustrates another fault condition. If the difference
between V
1B
, the inactive input, and V
1A
, the active input (that is,
being used for billing), becomes greater than 6.25% of V
1B
, the
FAULT indicator goes active, and there is also a swap over to the
V
1B
input. The analog input V
1B
becomes the active input. Again,
there is a time constant of about 3 s associated with this swap.
V
1A
does not swap back to being the active channel until V
1A
is
greater than V
1B
and the difference between V
1A
and V
1B
—in this
order—becomes greater than 6.25% of V
1A
. However, the
FAULT indicator becomes inactive as soon as V
1A
is within
6.25% of V
1B
. This threshold eliminates potential chatter
between V
1A
and V
1B
.
V
1B
V
1N
V
1A
AGND
FILTER
AND
COMPARE
TO
MULTIPLIER
FAULT
A
B
V
1A
V
1B
V
1A
< 93.75% OF V
1B
>0
<0
ACTIVE POINT – INACTIVE INPUT
6.25% OF INACTIVE INPUT
0
0V
FAULT + SWAP
V
1A
V
1B
Figure 27. Fault Conditions for Inactive Input Greater than Active Input
Calibration Concerns
Typically, when a meter is being calibrated, the voltage and
current circuits are separated as shown in Figure 28. This means
that current passes through only the phase or neutral circuit.
Figure 28 shows current being passed through the phase circuit.
This is the preferred option, because the ADE7761 starts billing
on the input V
1A
on power-up. The phase circuit CT is con-
nected to V
1A
in the diagram. Since there is no current in the
neutral circuit, the FAULT indicator comes on under these
conditions. However, this does not affect the accuracy of the
calibration and can be used as a means to test the functionality
of the fault detection.
AGND
V
1B
V
1N
V
1A
R
F
R
F
C
F
C
F
CT
CT
RB
RB
0V
V
1A
IB
IB
P
N
*RB + VR = RF
VR*
RB*
RA*
V
2P
R
F
V
2N
C
T
C
F
V
TEST
CURRENT
240V RMS
0
Figure 28. Fault Conditions for Inactive Input Greater than Active Input
If the neutral circuit is chosen for the current circuit in the
arrangement shown in Figure 28, this may have implications for
the calibration accuracy. The ADE7761 powers up with the V
1A
input active as normal. However, because there is no current in
the phase circuit, the signal on V
1A
is zero. This causes a fault to
be flagged and the active input to be swapped to V
1B
(neutral).
The meter can be calibrated in this mode, but the phase and
neutral CTs might differ slightly. Because under no-fault condi-
tions all billing is carried out using the phase CT, the meter
should be calibrated using the phase circuit. Of course, both
phase and neutral circuits can be calibrated.
MISSING NEUTRAL MODE
The ADE7761 integrates a novel fault detection that warns and
allows the ADE7761 to continue to bill in case a meter is
connected to only one wire (see Figure 29). For correct
operation of the ADE7761 in this mode, the V
DD
pin of the
ADE7761 must be maintained within the specified range (5 V ±
5%). The missing neutral detection algorithm is designed to
work over a line frequency of 45 Hz to 55 Hz.
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相關(guān)代理商/技術(shù)參數(shù) |
參數(shù)描述 |
|---|---|
| ADE7761B | 制造商:AD 制造商全稱:Analog Devices 功能描述:Energy Metering IC with On-Chip Fault and Missing Neutral Detection |
| ADE7761BARS | 制造商:Rochester Electronics LLC 功能描述: 制造商:Analog Devices 功能描述: |
| ADE7761BARS-REF | 制造商:AD 制造商全稱:Analog Devices 功能描述:Energy Metering IC with On-Chip Fault and Missing Neutral Detection |
| ADE7761BARS-RL | 制造商:AD 制造商全稱:Analog Devices 功能描述:Energy Metering IC with On-Chip Fault and Missing Neutral Detection |
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