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 115: Simplified block diagram of pole discordance function - contact and
current based
The pole discrepancy protection is blocked if the input signal BLOCK is high.
The BLOCK signal is a general purpose blocking signal of the pole discordance
protection. It can be connected to a binary input in the IED in order to receive a block
command from external devices or can be software connected to other internal
functions in 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.
If the pole discordance protection is enabled, then two different criteria can generate
a trip signal TRIP:
• Pole discordance signaling from the circuit breaker.
• Unsymmetrical current detection.
8.6.7.1 Pole discordance signaling from circuit breaker
If one or two poles of the circuit breaker have failed to open or to close (pole
discordance status), then the function input EXTPDIND is activated from the pole
discordance signal in figure
114. After a settable time tTrip, a 150 ms trip pulse
command TRIP is generated by the pole discordance function.
8.6.7.2 Unsymmetrical current detection
Unsymmetrical current indicated if:
Section 8 1MRK 502 048-UEN A
Current protection
230
Technical manual
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