Beluk KSR-Z, Technical Documentation Manual

Page: 9 / 36

Technical Documentation
KSR-Z – Capacitor-Bank Protection Relay
Rev. 04
Page
9
/
36
2.3 Other features
2.3.1 Natural unbalance compensation
The KSR-Z contains the function "natural unbalance compensation". This function allows to
measure and store the natural unbalance current
(
I
nuc
)
at the protected capacitor banks. The value
of the natural unbalance current depends on production tolerances of the used capacitors. The
unbalance current is measured in the star point connection of two stages. This current can be
compensated in amplitude and phase angle to zero, to detect further changes in phase angle and
absolute value. During the normal operation the KSR-Z subtracts the stored I
nuc
value from the
current I
n.
The result of this operation should be "0". In case of variations of this result it is possible
to set a threshold between 0.01A and 50kA to trigger an alarm.
Attention: The natural unbalance compensation is only possible with a voltage signal between L1
– N and a current signal at current channel 1. This signals are needed get the information of the
phase angle and absolute value.
2.3.2 Metering functions
The KSR-Z metering features provide continuous measurement of Currents and Voltages which are
connected as analogue inputs. The signal processor calculates different values from these inputs.
V
Line to Neutral
TRMS Voltages V
L1-N
, V
L2-N
, V
L3-N
V
Line to Line
TRMS Voltages V
L1-L2
, V
L2-L3
, V
L3-L1
THD THD
– factors for voltages (
V
Line to Neutral
) and currents ( I
L1
, I
L2
, I
L3
, I
UB
)
I TRMS Current I
L1
, I
L2
, I
L3
, I
UB
If RMS values of fundamental waves of currents I
L1
, I
L2
, I
L3
and I
UB
(without harmonics)
I UC4 Unbalanced current compensated value I
UC4
I EF Earth fault current actual value I
EF
and compensated value I
EF-cp
Ith exponentially damped current values of I
L1
, I
L2
, I
L3
and I
UB
to simulate
thermal measurement
1
T ambient temperature
Harmonics Order of (3-51) for current and voltages (only
ODD harmonic orders)
1
Please check Appendix A for detailed explaination of thermal damping function.