8.6.6 Monitored data
Table 119: CCRPLD Monitored data
Name
Type Values (Range) Unit Description
IMin REAL - A Lowest phase current
IMax REAL - A Highest phase current
8.6.7 Operation principle
The detection of pole discordance can be made in two different ways. If the contact
based function is used an external logic can be made by connecting the auxiliary
contacts of the circuit breaker so that a pole discordance is indicated, see figure 114.
Pole discordance signal from circuit breaker
+
circuit breaker
en05000287.vsd
IEC05000287 V2 EN
Figure 114: 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.
1MRK 502 048-UEN A Section 8
Current protection
229
Technical manual
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