Delta Current And Delta Voltage Detection - ABB RES670 Technical Manual

Section 13
Secondary system supervision
13.2.7.2
372
internal functions of the IED itself in order to receive a block command from internal
functions. Through OR gate it can be connected to both binary inputs and internal
function outputs.
The input BLKTRIP is intended to be connected to the trip output from any of the
protection functions included in the IED. When activated for more than 20 ms, the
operation of the fuse failure is blocked; a fixed drop-out timer prolongs the block for
100 ms. The aim is to increase the security against unwanted operations during the
opening of the breaker, which might cause unbalance conditions for which the fuse
failure might operate.
The output signal BLKZ will also be blocked if the internal dead line detection is
activated. The dead line detection signal has a 200 ms drop-out time delay.
The input signal MCBOP is supposed to be connected via a terminal binary input to the
N.C. auxiliary contact of the miniature circuit breaker protecting the VT secondary
circuit. The MCBOP signal sets the output signals BLKV and BLKZ in order to block
all the voltage related functions when the MCB is open independent of the setting of
OpModeSel selector. The additional drop-out timer of 150 ms prolongs the presence of
MCBOP signal to prevent the unwanted operation of voltage dependent function due to
non simultaneous closing of the main contacts of the miniature circuit breaker.
The input signal 89b is supposed to be connected via a terminal binary input to the
N.C. auxiliary contact of the line disconnector. The 89b signal sets the output signal
BLKV in order to block the voltage related functions when the line disconnector is
open. The impedance protection function is not affected by the position of the line
disconnector since there will be no line currents that can cause malfunction of the
distance protection. If 89b=0 it signifies that the line is connected to the system and
when the 89b=1 it signifies that the line is disconnected from the system and the block
signal BLKV is generated.
The output BLKV can be used for blocking the voltage related measuring functions
(undervoltage protection, energizing check and so on) except for the impedance
protection.
The function output BLKZ shall be used for blocking the impedance protection
function.

Delta current and delta voltage detection

A simplified diagram for the functionality is found in figure 131. The calculation of the
changes of currents and voltages is based on a sample analysis algorithm. The
calculated delta quantities are compared with their respective set values DIPU and
DVPU. The algorithm detects a fuse failure if a sufficient change in voltage without a
sufficient change in current is detected in each phase separately. The following
quantities are calculated in all three phases:
1MRK 511 408-UUS A
Phasor measurement unit RES670 2.2 ANSI
Technical manual
M13685-3 v7