8.8.1 IdentificationM14888-1 v4Function description IEC 61850identificationIEC 60617identificationANSI/IEEE C37.2device numberPole discordance protection CCPDSCPDSYMBOL-S V1 EN-US52PD8.8.2 Application M13270-3 v6There is a risk that a circuit breaker will get discordance between the poles at circuit breakeroperation: closing or opening. One pole can be open and the other two closed, or two polescan be open and one closed. Pole discordance of a circuit breaker will cause unsymmetricalcurrents 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 earth-faultprotections in the power system.It is therefore important to detect situations with pole discordance of circuit breakers. Whenthis is detected the breaker should be tripped directly.Pole discordance protection CCPDSC will detect situation with deviating positions of the polesof the protected circuit breaker. The protection has two different options to make thisdetection:• By connecting the auxiliary contacts in the circuit breaker so that logic is created, a signalcan be sent to the protection, indicating pole discordance. This logic can also be realizedwithin the protection itself, by using opened and close signals for each circuit breakerpole, connected to the protection.• Each phase current through the circuit breaker is measured. If the difference between thephase currents is larger than aCurrUnsymLevel this is an indication of pole discordance,and the protection will operate.8.8.3 Setting guidelines M13274-3 v8The parameters for the Pole discordance protection CCPDSC are set via the local HMI orPCM600.The following settings can be done for the pole discordance protection.GlobalBaseSel: Selects the global base value group used by the function to define (IBase),(UBase) and (SBase).Operation:Off orOntTrip: Time delay of the operation.ContSel: Operation of the contact based pole discordance protection. Can be set:Off/PDsignal from CB. IfPD signal from CB is chosen the logic to detect pole discordance is made inthe vicinity to the breaker auxiliary contacts and only one signal is connected to the polediscordance function. If thePole pos aux cont. alternative is chosen each open close signal isconnected to the IED and the logic to detect pole discordance is realized within the functionitself.Section 8 1MRK 505 363-UEN ACurrent protection168Application manual
