Thytronic NV10B - Residual Voltage Calculation Examples

CHARACTERISTICS
40
NV10B - Manual - 04 - 2022
Example B1
The relay residual nominal voltage U
En
may be estimated by means of the following general for-
mula:
U
En
= (U
ng
/√3) /K
VT
= (10000 /√3) / (110/ √3) = 91 V
Example B2
The relay residual nominal voltage U
En
may be estimated by means of the following general for-
mula: U
En
= (U
ng
/√3) /K
VT
= (6000 /√3) / (60/ √3) = 100 V
Case C
The relay residual calculated nominal voltage U
ECn
is estimated automatically by means of the for-
mula: U
ECn
= √3∙ U
n
Example C1
According with the example 2 where U
En
= 100 V the relay residual calculated nominal voltage U
ECn
is calculated inside the relay as: U
ECn
= U
n
∙ √3 = 100 ∙ √3 = 173 V
• VTs Phase primary voltage U
np
(phase-to-phase)
This parameter affects the measure of the input voltages when the primary measurement reading
mode is selected.
If the formerly indications concerning the relay nominal voltage U
n
are complied (Phase to ground
and phase-to-phase VTS connection diagrams), then the U
np
setting must be adjusted to:
U
np
= grid nominal voltage [V]].
EsB1-UEn.ai
K
VT
=
/ V
V
11000
3
3
100
= 110 /
K
VT
=
/ V
V
11000
3
3
100
= 110 /
Grid nominal voltage U
ng
= 10 kV
Ratio of VT connected from star neutral to ground:
U
ng
= 10 kV
NV10B
U
En
EsB2-UEn.ai
K
VT
=
/ V
V
6000
3
3
100
= 60 /
K
VT
=
/ V
V
6000
3
3
100
= 60 /
Grid nominal voltage U
ng
= 6kV
Ratio of VT connected from star neutral to ground:
U
ng
= 6 kV
U
En
NV10B
Es4-UEn.ai
K
VT
=
/
/
V
V
6000
3
100 3
= 60
/
/
V
V
6000
3
100 3
= 60
Grid nominal voltage U
ng
= 6 kV
Ratio of line VTs K
VT
= U
np
/U
ns
=
U
ng
= 6 kV
U
n
, U
ECn
52
NV10B