8517
133
VUB4
5
Block OFF
In the register of the VUB function is recorded start, trip or blocked “On” event process data. In the
table below is presented the structure of VUB function register content. This information is available in
12 last recorded events for all provided instances separately.
Table. 5.4.14. - 136. Register content.
Date & Time
Event code
Trigger
voltage
Fault voltage
Prefault
voltage
Trip time
remaining
Used
SG
dd.mm.yyyy
hh:mm:ss.mss
8320 -
8517 Descr.
Start average
voltage
Trip -20ms
averages
Start -200ms
averages
0ms - 1800s
1 - 8
5.4.15. Over- and underfrequency f>/< (81O/81U)
Frequency protection function can be used for both under frequency and over frequency situations and
it has four stages for both. Frequency protection can be applied to protect feeder, bus, transformer,
motor and generator applications. Difference between generated power and load demand can cause
the frequency to drop below or rise above the allowed level. When the consumption is larger than the
generated power the frequency may drop. When more power is generated than is consumed over
frequency can occur.
In generator applications too big load or malfunction in power controller can cause frequency to
decrease. Under frequency causes damage to turbine wings through vibration, heating due to
increased iron losses, dropped cooling effectivity and over magnetization in step-up transformer. Over
frequency protection prevents the generator from running too fast which can cause damage to the
generator turbine.
Under frequency and over frequency protection can be used as an indicator of accidental island
operation of distributed generation and some consumers since it is unlikely that the consumed and
generated power are the same. Over frequency is also often used to control power generation to keep
the system frequency consistent.
Activation and deactivation of each individual stage can be done inside the protection function menus
info-tab.
Outputs of the function are Start Trip and Blocked signals. Setting parameters are static inputs for the
function which are changed only by user input in the setup phase of the function. Frequency protection
utilizes total of eight separate setting groups which can be selected from one common source.
The function can operate on instant or time delayed mode.
The operational logic consists of input magnitude processing, threshold comparator, two block signal
check, time delay characteristics and output processing.
Inputs for the function are the operating mode selections, setting parameters and measured and pre-
processed frequency magnitudes and binary input signals. Function outputs START, TRIP and
BLOCKED signals which can be used for direct IO controlling and also for user logic programming. The
function registers its operation into 12 last time-stamped registers and also generates general time
stamped ON/OFF events to the common event buffer from each of the three output signal. In instant
operating mode the function outputs START and TRIP events simultaneously with equivalent time
stamp. Time stamp resolution is 1ms. Function provides also cumulative counters for START, TRIP and
BLOCKED events.
In the following gure is presented the simpli ed function block diagram of the FRQV function.
AQ-F255
Instruction manual
Version: 2.00
© Arcteq Relays Ltd
146
