ABB REG650 Technical Manual page 196

Section 7
Current protection
190
circuit breaker
IEC05000287 V2 EN
Figure 98: 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.
ContSel
EXTPDIND
CLOSECMD tTrip+200 ms
OR
OPENCMD
CurrSel
Unsymmetrical
current detection
IEC08000014 V2 EN
Figure 99: Simplified block diagram of pole discordance function - contact and
current based
The pole discordance protection is blocked if the input signal BLOCK is high.
+
Pole discordance signal from circuit breaker
AND
OR
AND
1MRK 502 034-UEN -
en05000287.vsd
tTrip 150 ms
t
AND
IEC08000014-2-en.vsd
Technical Manual
TRIP