ADE9078ACPZ datasheet(59/108 Pages) AD

59 / 108 page

ADE9078

Data Sheet

Rev. 0 | Page 58 of 107

NON-BLONDEL COMPLIANT METERS

Blondel’s theorem states that there must be n − 1 measuring

elements in a meter, where n is the number of the wires of the

electric system. In this way, a Blondel compliant 4-wire wye or

4-wire delta measures three voltages and three currents. In a

3-wire delta service, at least two voltages and two currents must

be measured to be Blondel compliant.

IEC meter forms are all Blondel compliant. ANSI has some meter

forms that are not Blondel compliant, meaning that there are

fewer than n − 1 elements, so that in a 4-wire wye or 4-wire delta

configuration, two voltages and three currents are measured. The

ADE9078 has provisions to deal with non-Blondel compliant meter

forms. Use the VCONSEL bits in the ACCMODE register to select

what calculation to use for VB based on the VA and VC signals.

Table 23. Non-Blondel Compliant Meter Forms

Service Type

Non-Blondel

Compliant

ANSI Meter

Form

VCONSEL

Calculation

4-Wire Wye, Two Voltages,

Three Currents

6S, 7S, 14S, 29S,

36S, 46S, 76S

010

VB = −VA −

4-Wire Delta, Two

Voltages, Three Currents

8S, 15S, 24S

011

VB = −VA

APPLYING THE ADE9078 TO A 4-WIRE WYE SERVICE

For the highest level of performance when measuring a 4-wire

wye service, connect the neutral to ground, as shown in Figure 89.

For this configuration, VCONSEL = 000.

VAP

VBP

VCP

VAN

AGND

DGND

NEUTRAL

VBN

VCN

VBN

220V

–120°

0.353V

220V

120°

0.353V

PHASE C

VCN

PHASE A

PHASE B

VAN

220V

0°

220V

–120°

220V

120°

PHASE C

PHASE A

PHASE B

220V

0°

0.353V 0°

VCONSEL = 000

VA, VB, VC

Figure 89. 4-Wire Wye, Neutral Connected to Ground

Alternatively, a series impedance can be used on the neutral, as

shown in Figure 90, which can be advantageous if an isolated

power supply is used. Note that this configuration has poor

performance if the phase voltages are not balanced. For more

information, see the AN-1334 Application Note. For this

configuration, VCONSEL = 000.

NEUTRAL

VAP

VBP

VCP

VAN

AGND

DGND

VBN

VCN

VBN

220V

–120°

0.353V

220V

120°

0.353V

PHASE C

VCN

PHASE A

PHASE B

220V

0°

220V

–120°

220V

120°

PHASE C

PHASE A

PHASE B

220V

0°

0.353V 0°

VCONSEL = 000

VA, VB, VC

NEUTRAL ATTENUATION

NETWORK

Figure 90. 4-Wire Wye, Series Impedance on the Neutral

Phase sequence error detection is performed based on the

expected ABC sequence (see the Phase Sequence Error

Detection section for more information).

To calculate the overall power consumed by the system (active,

reactive, and apparent), add the contribution from the Phase A,

Phase B, and Phase C accumulations.

ADE9078ACPZ датащи(PDF) 59 Page - Analog Devices

ADE9078ACPZ датащи(HTML) 59 Page - Analog Devices

Html Pages

1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60 61 62 63 64 65 66 67 68 69 70 71 72 73 74 75 76 77 78 79 80 81 82 83 84 85 86 87 88 89 90 91 92 93 94 95 96 97 98 99 100 ...More

датащи скачать

ссылки URL