Description
Measurements and Derived Values
The device measures and calculates the values which are displayed on the HMI/Modbus. The following table
shows the measured values and derived values of the device when it is connected to the medium-voltage
system and low-voltage system.
Table 4-1
Measurements and Derived Values
Measurements
Derived Values
Phase I
1
, phase I
2
, phase I
3
I
N
and 2nd harmonic of the phase current
Phase I
1
, ground I
N
, phase I
3
I
2
and 2nd harmonic of the phase current
Phase V
1
, V
2
, V
3
Phase-to-phase voltages (V12, V23, V31)
Frequency 50 Hz/60 Hz
–
–
Active power, reactive power, and apparent power
–
cos φ (power factor)
–
Phase angle
–
Active import energy, active export energy, reactive import energy, and
reactive export energy
Fault Detection
The device determines the fault based on the following criteria:
•
Overcurrent detection for phase currents (I>, I>>) and ground current (I
N
>)
•
Ground-current and neutral-point displacement voltage (I
N
> and V
NG
>) for resonant-grounded/isolated
system
where V
NG
is an internally calculated value.
You can configure the individual time-delay setting for phase current and ground currents.
Table 4-2
Timer Configuration
tI>
Timer for the low-set current threshold I>
tI>>
Timer for the high-set current threshold I>>
tI
N
>
Timer for the ground-current threshold I
N
>
tV
NG
>
Timer for neutral-point displacement voltage V
NG
>
i
i
NOTE
For fault detection, the highest values of one of the timers are considered.
The device uses the Definite Minimum Time (DMT) or Inverse Definite Minimum Time (IDMT) characteristics
for detecting the fault. It identifies the type of the fault and also determines the direction.
The following logic diagram shows the fault indication.
4.1
4.1.1
4.1.2
Device Functions
4.1 Description
30
SICAM, Feeder Condition Monitor, Manual
E50417-H8940-C580-A4, Edition 03.2019