measurement is activated (and phase-to-phase measurement is blocked). The relations are
defined by the following equation.
0
max
Re
3
100
ph
IN
leasePE
I
I
×
³
×
EQUATION2548 V1 EN-US
(Equation 424)
Where:
INReleasePE
is the setting for the minimum residual current needed to enable operation in the phase-to-
earth fault loops in %
Iphmax
is the maximum phase current in any of three phases
By default this setting is set excessively high to always enable phase-to-phase measurement
for phase-to-phase-earth faults. Maintain this default setting value unless there are very
specific reasons to enable phase-to-earth measurement. Please note that, even with the
default setting value, phase-to-earth measurement is activated whenever appropriate, like in
the case of simultaneous faults: two earth faults at the same time, one each on the two
circuits of a double line.
7.14
Power swing detection ZMRPSB
IP14499-1 v3
7.14.1
Identification
M14853-1 v3
Function description
IEC 61850
identification
IEC 60617
identification
ANSI/IEEE C37.2
device number
Power swing detection
ZMRPSB
Zpsb
SYMBOL-EE V1 EN-US
68
7.14.2
Application
IP14969-1 v1
7.14.2.1
General
M13874-3 v3
Various changes in power system may cause oscillations of rotating units. The most typical
reasons for these oscillations are big changes in load or changes in power system
configuration caused by different faults and their clearance. As the rotating masses strive to
find a stable operate condition, they oscillate with damped oscillations until they reach the
final stability.
The extent of the oscillations depends on the extent of the disturbances and on the natural
stability of the system.
The oscillation rate depends also on the inertia of the system and on the total system
impedance between different generating units. These oscillations cause changes in phase and
amplitude of the voltage difference between the oscillating generating units in the power
system, which reflects further on in oscillating power flow between two parts of the system -
the power swings from one part to another - and vice versa.
Distance IEDs located in interconnected networks see these power swings as the swinging of
the measured impedance in relay points. The measured impedance varies with time along a
Section 7
1MRK 505 343-UEN B
Impedance protection
364
Application manual
Summary of Contents for Relion 670 series
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