6.9 Pole discrepancy protection CCRPLD (52PD)
6.9.1 Identification
Function description IEC 61850
identification
IEC 60617
identification
ANSI/IEEE C37.2
device number
Pole discrepancy protection CCRPLD
SYMBOL-S V1 EN
52PD
6.9.2 Functionality
Circuit breakers and disconnectors can end up with their phases in different positions
(close-open), due to electrical or mechanical failures. An open phase can cause negative
and zero sequence currents which cause thermal stress on rotating machines and can cause
unwanted operation of zero sequence or negative sequence current functions.
Normally the affected breaker is tripped to correct such a situation. If the situation
warrants the surrounding breakers should be tripped to clear the unsymmetrical load
situation.
The pole discrepancy function operates based on information from the circuit breaker
logic with additional criteria from phase selective current unsymmetry.
6.9.3 Function block
ANSI08000041-1-en.vsd
CCRPLD (52PD)
I3P*
BLOCK
CLOSECMD
OPENCMD
EXTPDIND
TRIP
PICKUP
ANSI08000041 V1 EN
Figure 59: CCRPLD (52PD) function block
1MRK 511 287-UUS A Section 6
Current protection
145
Technical manual
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