1477
23
NOC4
5
Block OFF
1478
23
NOC4
6
Phase A Start On
1479
23
NOC4
7
Phase A Start Off
1480
23
NOC4
8
Phase B Start On
1481
23
NOC4
9
Phase B Start Off
1482
23
NOC4
10
Phase C Start On
1483
23
NOC4
11
Phase C Start Off
1484
23
NOC4
12
Phase A Trip On
1485
23
NOC4
13
Phase A Trip Off
1486
23
NOC4
14
Phase B Trip On
1487
23
NOC4
15
Phase B Trip Off
1488
23
NOC4
16
Phase C Trip On
1489
23
NOC4
17
Phase C Trip Off
In the register of the NOC function is recorded start, trip or blocked “On” event process data. In the
table below is presented the structure of NOC function register content. This information is available in
12 last recorded events for all provided instances separately.
Table. 5.4.1. - 54. Register content.
Date & Time
Event
code
Fault type
Trigger
current
Fault
current
Prefault
current
Trip time
remaining
Used
SG
dd.mm.yyyy
hh:mm:ss.mss
1280-1489
Descr.
L1-G …
L1-L2-L3
Start average
current
Trip -20 ms
averages
Start -200 ms
averages
0ms -1800s
1 - 8
5.4.2. Non-directional earth fault I0> (50N/51N)
Non-directional earth fault function (NEF) is used for instant- and time delayed earth fault protection for
various applications including feeder, lter and machine applications of utilities and industry. The
number of available instances of the function depends of the IED model. Function measures constantly
selected neutral current magnitudes which on the operating decisions are based. Available analog
measuremen channels are Io1 and Io2 residual current measurement channels and IoCalc which is
residual current calculated form phase current analog channels. These analog channels use either
fundamental component RMS, TRMS values (including harmonics up to 32
nd
) or peak-to-peak values
which is user selectable. Blocking signal and setting group selection controls the operating
characteristics of the function during normal operation.
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. Non-directional
overcurrent function utilizes total of eight separate setting groups which can be selected from one
common source.
The function can be operating on instant or time delayed mode. In time delayed mode the operation
can be switched to de nite time or IDMT mode. For IDMT operation IEC and ANSI standard time
delays are supported as well as custom parameters. Function includes saturation checking which
allows the function to start and operate accurately also in case of CT saturation condition.
The operational logic consists of input magnitude processing, input magnitude selection, saturation
check, threshold comparator, block signal check, time delay characteristics and output processing.
AQ-T257
Instruction manual
Version: 2.00
47
© Arcteq Relays Ltd