CHARACTERISTICS
24
NV10B - Manual - 04 - 2022
4.3 I/O DESCRIPTION
Metering inputs
The following inputs are provided:
• Three phase voltage inputs with programmable nominal voltages within range 50...130 V (
U
R
=100 V)
or 200...520 V (
U
R
= 400 V) to be select on order. The nominal voltages is user adjustable inside a
wide setting range, so the relays can be employed on plants with TV different secondary voltages
(50...130 V for versions with
U
R
= 100 V and 200...520 V for versions with
U
R
= 400 V). The version with
U
R
= 400V allows a direct measure without interposing VTs for low voltage applications (200...520
V nominal voltage).
• One residual voltage input, with programmable nominal voltage within range 50...130 V (
U
ER
=100 V);
The input circuits are appropriately dimensioned in order to withstand the voltages which arise
when a fault occurs, both in transient and steady state condition.
Signal processing
Various processing levels are involved:
• Acquisition (base level).
• Direct measures of physical channels (first level).
• Calculated measures (second level).
• Derived (third level).
The measures concerning a level are based on data worked out in the previous level.
For each level the required resources concerning the priority for tasks (conditioning circuits, DSP
and CPU) are on hand.
ACQUISITION (base level)
The input signals are sampled 24 times per period:
-
u
L1
...
u
L3
Input voltage instantaneous values
-
u
E
Residual voltage instantaneous value
From the sampled quantities, several measures are computed for protection, monitoring and meter-
ing purposes.
• Direct
• Calculated
Direct
• Frequency. The measure of period is taken from voltage inputs.
sensori-en.ai
3 line voltage inputs
NV10
1 residual voltage input
acquisizione-en.ai
ACQUISITION
INSTANTANEOUS MEASURES
≈
F.ai
(Hz)
u
L1
u
L2
U
L1
U
L2
ACQUISITION
VT
≈
≈
u
L3
U
L3
≈
f
T