
UMG 509-PRO
34
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7.7.2
Current measurement
Here are some circuit diagrams of the most common connection methods for current measurement.
L1
L2
L3
N
V
1
V
2
V
3
V
4
V
ref
3p 4wu
L1
L2
L3
N
V
1
V
2
V
3
V
4
V
ref
3p 4w
L1
L2
V
1
V
2
V
3
V
4
V
ref
1p 2w
L1
L2
L3
N
3p 2i
L1
L2
L3
3p 2i0
L1
L2
1p 2i
I
1
I
2
I
3
I
4
S1 S2 S1 S2 S1 S2 S1 S2
I
1
I
2
I
3
I
4
S1 S2 S1 S2 S1 S2 S1 S2
I
1
I
2
I
3
I
4
S1 S2 S1 S2 S1 S2 S1 S2
L1
L2
L3
N
3p 4w
I
1
I
2
I
3
I
4
S1 S2 S1 S2 S1 S2 S1 S2
L1
L2
L3
V
1
V
2
V
3
V
4
V
ref
3p 3wu
L
L
L
L
N
3p 5w
I
1
I
2
I
3
I
4
S1 S2 S1 S2 S1 S2 S1 S2
L1
L2
L3
V
1
V
2
V
3
V
4
V
ref
3p 3w
L
L
L
L
V
1
V
2
V
3
V
4
V
ref
3p 5w
N
Fig. Measurement in a three-phase 4-conductor network
via three current transformers
L1
L2
L3
N
V
1
V
2
V
3
V
4
V
ref
3p 4wu
L1
L2
L3
N
V
1
V
2
V
3
V
4
V
ref
3p 4w
L1
L2
V
1
V
2
V
3
V
4
V
ref
1p 2w
L1
L2
L3
N
3p 2i
L1
L2
L3
3p 2i0
L1
L2
1p 2i
I
1
I
2
I
3
I
4
S1 S2 S1 S2 S1 S2 S1 S2
I
1
I
2
I
3
I
4
S1 S2 S1 S2 S1 S2 S1 S2
I
1
I
2
I
3
I
4
S1 S2 S1 S2 S1 S2 S1 S2
L1
L2
L3
N
3p 4w
I
1
I
2
I
3
I
4
S1 S2 S1 S2 S1 S2 S1 S2
L1
L2
L3
V
1
V
2
V
3
V
4
V
ref
3p 3wu
L
L
L
L
N
3p 5w
I
1
I
2
I
3
I
4
S1 S2 S1 S2 S1 S2 S1 S2
L1
L2
L3
V
1
V
2
V
3
V
4
V
ref
3p 3w
L
L
L
L
V
1
V
2
V
3
V
4
V
ref
3p 5w
N
Fig. Measurement in a three-phase 3-conductor network
via two current transformers
L1
L2
L3
N
V
1
V
2
V
3
V
4
V
ref
3p 4wu
L1
L2
L3
N
V
1
V
2
V
3
V
4
V
ref
3p 4w
L1
L2
V
1
V
2
V
3
V
4
V
ref
1p 2w
L1
L2
L3
N
3p 2i
L1
L2
L3
3p 2i0
L1
L2
1p 2i
I
1
I
2
I
3
I
4
S1 S2 S1 S2 S1 S2 S1 S2
I
1
I
2
I
3
I
4
S1 S2 S1 S2 S1 S2 S1 S2
I
1
I
2
I
3
I
4
S1 S2 S1 S2 S1 S2 S1 S2
L1
L2
L3
N
3p 4w
I
1
I
2
I
3
I
4
S1 S2 S1 S2 S1 S2 S1 S2
L1
L2
L3
V
1
V
2
V
3
V
4
V
ref
3p 3wu
L
L
L
L
N
3p 5w
I
1
I
2
I
3
I
4
S1 S2 S1 S2 S1 S2 S1 S2
L1
L2
L3
V
1
V
2
V
3
V
4
V
ref
3p 3w
L
L
L
L
V
1
V
2
V
3
V
4
V
ref
3p 5w
N
Fig. Measurement in a three-phase 4-conductor network
with a symmetrical load
via two current transformers
L1
L2
L3
N
V
1
V
2
V
3
V
4
V
ref
3p 4wu
L1
L2
L3
N
V
1
V
2
V
3
V
4
V
ref
3p 4w
L1
L2
V
1
V
2
V
3
V
4
V
ref
1p 2w
L1
L2
L3
N
3p 2i
L1
L2
L3
3p 2i0
L1
L2
1p 2i
I
1
I
2
I
3
I
4
S1 S2 S1 S2 S1 S2 S1 S2
I
1
I
2
I
3
I
4
S1 S2 S1 S2 S1 S2 S1 S2
I
1
I
2
I
3
I
4
S1 S2 S1 S2 S1 S2 S1 S2
L1
L2
L3
N
3p 4w
I
1
I
2
I
3
I
4
S1 S2 S1 S2 S1 S2 S1 S2
L1
L2
L3
V
1
V
2
V
3
V
4
V
ref
3p 3wu
L
L
L
L
N
3p 5w
I
1
I
2
I
3
I
4
S1 S2 S1 S2 S1 S2 S1 S2
L1
L2
L3
V
1
V
2
V
3
V
4
V
ref
3p 3w
L
L
L
L
V
1
V
2
V
3
V
4
V
ref
3p 5w
N
Fig. Measurement in a single-phase 2-conductor network
via 2 current transformers
L1
L2
L3
N
V
1
V
2
V
3
V
4
V
ref
3p 4wu
L1
L2
L3
N
V
1
V
2
V
3
V
4
V
ref
3p 4w
L1
L2
V
1
V
2
V
3
V
4
V
ref
1p 2w
L1
L2
L3
N
3p 2i
L1
L2
L3
3p 2i0
L1
L2
1p 2i
I
1
I
2
I
3
I
4
S1 S2 S1 S2 S1 S2 S1 S2
I
1
I
2
I
3
I
4
S1 S2 S1 S2 S1 S2 S1 S2
I
1
I
2
I
3
I
4
S1 S2 S1 S2 S1 S2 S1 S2
L1
L2
L3
N
3p 4w
I
1
I
2
I
3
I
4
S1 S2 S1 S2 S1 S2 S1 S2
L1
L2
L3
V
1
V
2
V
3
V
4
V
ref
3p 3wu
L
L
L
L
N
3p 5w
I
1
I
2
I
3
I
4
S1 S2 S1 S2 S1 S2 S1 S2
L1
L2
L3
V
1
V
2
V
3
V
4
V
ref
3p 3w
L
L
L
L
V
1
V
2
V
3
V
4
V
ref
3p 5w
N
Fig. Measurement in a three-phase 4-conductor network
via four current transformers