REV. PrB 08/01

–7–

PRELIMINARY TECHNICAL DATA

ADE7752

Meter connections

In three phase service, two main power distribution services

exist: 3-phase 4-wire or 3-phase 3-wire. The additional wire

in the 3-phase 4-wire arrangement is the Neutral wire. The

voltage lines have a phase difference of ±120° (± 2

π/3

radians) between each other - See Equation 5.

)

3

4

cos(

2

)

(

)

3

2

cos(

2

)

(

;

)

cos(

2

)

(

π

ω

π

ω

ω

+

⋅

⋅

=

+

⋅

⋅

=

⋅

⋅

=

t

V

t

V

t

V

t

V

t

V

t

V

l

C

C

l

B

B

l

A

A

(5)

different phases

The current inputs are represented by Equations 6,

)

3

4

cos(

2

)

(

)

3

2

cos(

2

)

(

;

)

cos(

2

)

(

C

l

C

C

B

l

B

B

A

l

A

A

t

I

t

I

t

I

t

I

t

I

t

I

ϕ

π

ω

ϕ

π

ω

ϕ

ω

+

+

⋅

⋅

=

+

+

⋅

⋅

=

+

⋅

⋅

=

(6)

of each phase and

φ

φ

φ

current and voltage channel of each phase.

The instantaneous powers can then be calculated as follows:

)

(

)

(

)

(

)

(

)

(

)

(

)

(

)

(

)

(

t

I

t

V

t

P

t

I

t

V

t

P

t

I

t

V

t

P

C

C

C

B

B

B

A

A

A

⋅

=

⋅

=

⋅

=

Then,

)

3

8

2

cos(

)

cos(

)

(

)

3

4

2

cos(

)

cos(

)

(

)

2

cos(

)

cos(

)

(

C

l

C

C

C

C

C

C

B

l

B

B

B

B

B

B

A

l

A

A

A

A

A

A

t

I

V

I

V

t

P

t

I

V

I

V

t

P

t

I

V

I

V

t

P

ϕ

π

ω

ϕ

ϕ

π

ω

ϕ

ϕ

ω

ϕ

+

+

⋅

⋅

−

⋅

⋅

=

+

+

⋅

⋅

−

⋅

⋅

=

+

⋅

⋅

−

⋅

⋅

=

(7)

As can be seen from Equation 7, in the ADE7752 the real

power calculation per phase is made when current and voltage

inputs of the one phase are connected to the same channel (A,

B or C). Then, the summation of each individual real power

calculation gives the total Real Power information. P(t) =

Figure 14 demonstrates the connections of the analog inputs

of the ADE7752 with the power lines in a 3-phase 3-wire

Delta service.

Source

CT

CT

Rb

Rb

IAP

IAN

Anti-aliasing

Filters

IBP

IBN

Anti-aliasing

Filters

Ra*

Rb*

VR*

Rf

Cf

Cf

VN

VAP

Ra*

Rb*

VR*

Cf

VBP

Load

Phase A

Phase B

Phase C

Figure 14 - 3-phase 3-wire meter connection with ADE7752

Note: Only 2 current inputs and 2 voltage inputs of the

ADE7752 are used in this case. The Real power calculated

by the ADE7752 does not depend on the selected channel.

Figure 15 demonstrates the connections of the analog inputs

of the ADE7752 with the power lines in a 3-phase 4-wire Wye

service.

Source

CT

CT

Rb

Rb

IAP

IAN

Anti-aliasing

Filters

ICP

ICN

Anti-aliasing

Filters

Ra*

Rb*

VR*

Rf

Cf

Cf

VN

VAP

Ra*

Rb*

VR*

Cf

VCP

Load

CT

Rb

IBP

IBN

Anti-aliasing

Filters

Ra*

Rb*

VR*

Cf

VBP

Phase A

Phase B

Phase C

Figure 15 - 3-phase 4-wire meter connection with ADE7752