Events and registers
The underexcitation function (abbreviated "URX" in event block names) generates events and registers
from the status changes in START, TRIP and BLOCKED. The user can select which event messages
are stored in the main event buffer: ON, OFF, or both.
The events triggered by the function are recorded with a time stamp and with process data values.
Table. 5.4.19 - 180. Event messages.
Event block name
Event names
URX1
Start ON
URX1
Start OFF
URX1
Trip ON
URX1
Trip OFF
URX1
Block ON
URX1
Block OFF
URX2
Start ON
URX2
Start OFF
URX2
Trip ON
URX2
Trip OFF
URX2
Block ON
URX2
Block OFF
The function registers its operation into the last twelve (12) time-stamped registers. The register of the
function records the ON event process data for START, TRIP or BLOCKED. The table below
presents the structure of the function's register content.
Table. 5.4.19 - 181. Register content.
Date and time
Event
Pre-trigger
impedance (Z)
Fault
impedance
(Z)
Pre-fault
impedance (Z)
Trip time
remaining
Used SG
dd.mm.yyyy
hh:mm:ss.mss
Event
name
Start/Trip -20ms
impedance
Start/Trip
impedance
Start -200ms
impedance
0 ms...1800s
Setting group
1...8 active
5.4.20 100 % stator earth fault protection (U03rd>; 64S)
When using conventional neutral overvoltage protection function (U0>; 59N) even in the best case
scenario at least 5 % of the stator remains outside the function's range. The 100 % stator earth fault
protection function (also known as neutral 3rd harmonic overvoltage protection) is used to detect earth
faults near the neutral point. When an Earth fault occurs near the neutral point, it does not produce
enough neutral voltage for a conventional neutral overvoltage protection to detect the fault. Generators
induce some of the 3
rd
harmonic neutral voltage; when there is an earth fault near the neutral point,
this function detects the drop in the 3
rd
harmonic neutral voltage and trips the breaker. If the
3
rd
harmonic neutral voltage induced by the generator is high enough, the whole stator can be
protected by combining the neutral overvoltage and the 100 % stator earth fault protection functions.
The figure below demonstrates the overlapping range of the neutral overvoltage and the 100 % stator
earth fault protection function.
Genera
Generattor Commander
or Commander
Instruction manual
Version: 2.07
© Arcteq Relays Ltd
IM00001
217
Содержание Generator Commander
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