4
Specifications are subject to change without notice
WM2-96DS0303
WM2-96
Mode of Operation
Accuracy class of the instrument as a relation of PI/Pn and cos
ϕ (power factor)
Test conditions:
V = 0.8 to 1.2 Un,
I = 0.1 to 1.2 In,
f = 48 to 62 Hz
Input
Star
Delta
Current
voltage
voltage
AV5
Un: 250 V
Un: 430 V
In: 5 A
PI/QI (installation power)
One phase system:
PI = UI · II · cos
ϕ
QI = UI · II · sin
ϕ
Three phase, 3-wire system:
PI =
√3 · UI · II · cos ϕ
QI =
√3 · UI · II · sin ϕ
Three phase, 4-wire system:
PI = 3 · UI · II · cos
ϕ
QI = 3 · UI · II · sin
ϕ
where:
UI = the real star voltage of
the electrical system being
measured.
I
= the maximum phase cur-
rent of the electrical system
being measured.
Cos
ϕ = the average cos ϕ of
the electrical system being
measured.
Pn /Qn (rated power of the
instrument):
One phase system:
Pn = Qn = Un · In · CT(ratio)
Three phase, 3-wire system:
Pn = Qn =
√3 · Un · In · CT(ratio)
Three phase, 4-wire system:
Pn = Qn = 3 · Un · In · CT(ratio)
where:
Un = the rated input voltage
of WM2-96.
In = the rated input current of
WM2-96.
CT (ratio)
= the value of the
current transformer ratio.
Example 1:
Model AV5.3 (3-wire system).
UI = 400 V (delta voltage)
II = 265 A (single phase cur-
rent)
Cos
ϕ = 0.85 (system power
factor) (CT=300A)
Un = 430 V
In = 5 A
CT (ratio) =
300
= 60
5
PI =
√3 · UI · II · cos ϕ
=
√3 · 400 · 265 · 0.85
= 155.87 kW
Pn =
√3 · Un · In · CT (ratio)
=
√3 · 430 · 5 · 60
= 233.17 kW
PI
=
155.87
= 0.698
Pn
223.17
Example 2:
Model AV5.3 (4-wire system).
UI = 230 V
II = 110 A (CT=300A)
Cos
ϕ = 0.85 (sin
ϕ = 0.52)
Un = 250 V
In = 5 A
CT (ratio) =
300 A
= 60
5 A
Qn = 3 · UI · II · sin
ϕ
= 3 · 230 · 110 · 0.52
= 39.46 kvar
Qn = 3 · Un · In · CT (ratio)
= 3 · 250 · 5 · 60
= 225 kvar
PI
=
39.46
= 0.175
Pn
225
In both examples the accura-
cy of the measurement is
1% f.s. when considering the
changing of the measured
voltage from 0.9 Un to 1 Un
and the measured current
from 0.1 In to 0.9 In with a
cos
ϕ of 0.85 (sin ϕ 0.52).
PI / Pn
1%
2%
1%
2%
5%
QI / Qn
Active Power
Reactive Power
Test conditions:
V = 0.8 to 1.2 Un,
I = 0.1 to 1.2 In,
f = 48 to 62 Hz
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