t: Time delay of the operation. Normally the function shall be instantaneous.
9.9 Pole discrepancy protection CCPDSC(52PD)
9.9.1 Identification
Function description IEC 61850
identification
IEC 60617
identification
ANSI/IEEE C37.2
device number
Pole discrepancy protection CCPDSC
SYMBOL-S V1 EN
52PD
9.9.2 Application
There is a risk that a circuit breaker will get discrepancy between the poles at circuit
breaker operation: closing or opening. One pole can be open and the other two closed, or
two poles can be open and one closed. Pole discrepancy of a circuit breaker will cause
unsymmetrical currents in the power system. The consequence of this can be:
• Negative sequence currents that will give stress on rotating machines
• Zero sequence currents that might give unwanted operation of sensitive ground-fault
protections in the power system.
It is therefore important to detect situations with pole discrepancy of circuit breakers.
When this is detected the breaker should be tripped directly.
Pole discordance protection CCPDSC (52PD) will detect situation with deviating
positions of the poles of the protected circuit breaker. The protection has two different
options to make this detection:
• By connecting the auxiliary contacts in the circuit breaker so that logic is created, a
signal can be sent to the protection, indicating pole discrepancy. This logic can also
be realized within the protection itself, by using opened and close signals for each
circuit breaker pole, connected to the protection.
• Each phase current through the circuit breaker is measured. If the difference between
the phase currents is larger than a CurrUnsymPU this is an indication of pole
discrepancy, and the protection will operate.
Section 9 1MRK 506 369-UUS -
Current protection
546 Line distance protection REL670 2.2 ANSI
Application manual
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