Event block name
Event names
CBF1
CBFP ON
CBF1
CBFP OFF
CBF1
Block ON
CBF1
Block OFF
CBF1
DO monitor ON
CBF1
DO monitor OFF
CBF1
Signal ON
CBF1
Signal OFF
CBF1
Phase current ON
CBF1
Phase current OFF
CBF1
Res current ON
CBF1
Res current 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 ACTIVATED, BLOCKED, etc. The table below
presents the structure of the function's register content.
Table. 5.4.8 - 98. Register content.
Date and
time
Event
Max
phase
current
Residual current
Time to RETR
Time to CBFP
Used SG
dd.mm.yyyy
hh:mm:ss.mss
Event
name
Highest
phase
current
I01, I02 channel or
calculated residual
current
Time remaining to
retrip activation
Time remaining to
CBFP activation
Setting
group 1...8
active
5.4.9 Low-impedance or high-impedance restricted earth fault/ cable end differential
protection (I0d>; 87N)
The low-impedance or high-impedance restricted earth fault function is used for residual differential
current measurement for transformers. This function can also be used as the cable end differential
function. The operating principle is low-impedance differential protection with bias characteristics the
user can set. A differential current is calculated with the sum of the phase currents and the selected
residual current input. In cable end differential mode the function provides natural measurement
unbalance compensation for higher operating sensitivity in monitoring cable end faults.
The restricted earth fault function constantly monitors phase currents and selected residual current
instant values as well as calculated bias current and differential current magnitudes.
The blocking signal and the setting group selection control the operating characteristics of the function
during normal operation, i.e. the user or user-defined logic can change function parameters while the
function is running.
The function uses a total of eight (8) separate setting groups which can be selected from one common
source. The operating mode of the function can be changed via setting group selection.
The operational logic consists of the following:
• input magnitude selection
A
AQ
Q-M257
-M257
Instruction manual
Version: 2.07
124
© Arcteq Relays Ltd
IM00021
Summary of Contents for AQ-M257
Page 1: ...AQ M257 Motor protection IED Instruction manual...
Page 2: ......
