ABB REC650 - Page 145

Pole discordance signal from circuit breaker
+
circuit breaker
en05000287.vsd
IEC05000287 V2 EN
Figure 60: Pole discordance external detection logic
This binary signal is connected to a binary input of the IED. The appearance of this
signal will start a timer that will give a trip signal after the set time delay.
Pole discordance can also be detected by means of phase selective current
measurement. The sampled analog phase currents are pre-processed in a discrete
Fourier filter (DFT) block. From the fundamental frequency components of each
phase current the RMS value of each phase current is derived. The smallest and the
largest phase current are derived. If the smallest phase current is lower than the setting
CurrUnsymLevel times the largest phase current the settable trip timer (tTrip) is
started. The tTrip timer gives a trip signal after the set delay. The TRIP signal is a pulse
150 ms long. The current based pole discordance function can be set to be active either
continuously or only directly in connection to breaker open or close command.
B
L
O
C
K
ContSel
AND
EXTPDIND
Unsymmetrical
current detection
OR
CLOSECMD
OPENCMD
tTrip+200 ms
AND
OR
AND
TRIP
t
tTrip 150 ms
CurrSel
IEC08000014-2-en.vsd
IEC08000014 V2 EN
Figure 61: Simplified block diagram of pole discordance function - contact and
current based
The pole discrepancy protection is blocked if the input signal BLOCK is high.
1MRK 511 287-UEN A Section 6
Current protection
139
Technical manual