16.8.7.2 Application
Negative sequence symmetrical components are present in all types of fault condition. In
case of three phase short circuits the negative sequence voltages and current have transient
nature and will therefore decline to zero after some periods.
Negative sequence overvoltage protection (LCNSPTOV, 47) is a definite time stage
comparator function. The negative sequence input voltage from the SMAI block is
connected as input to the function through a group connection V3P in PCM600. This
voltage is compared against the preset value and a pickup signal will be set high if the input
negative sequence voltage is more than the preset value Pickup2. Trip signal will be set
high after a time delay setting of tV2. There is a BLOCK input which will block the
complete function. BLKTR will block the trip output. Negative sequence voltage is also
available as service value output U2.
16.8.7.3 Setting guidelines
GlobalBaseSel: Selects the global base value group used by the function to define IBase,
VBase and SBase as applicable.
Pickup2: Level of high negative sequence voltage detection given in % of VBase. This
setting should be based on fault calculations to find the negative sequence voltage in case
of a fault at the most remote point where the direct trip scheme shall be active. The
negative sequence voltages shall be calculated for different types of faults (single phase to
ground, phase to phase to ground and phase to phase short circuits) at different switching
states in the network.
tV2: Time delay for trip in case of high negative sequence voltage detection. The trip
function can be used as stand alone short circuit protection with a long time delay. The
choice of time delay is depending on the application of the protection as well as network
topology.
16.8.8 Zero sequence overvoltage protection LCZSPTOV (59N)
16.8.8.1 Identification
Function description
IEC 61850
identification
IEC 60617
identification
ANSI/IEEE C37.2
device number
Zero sequence overvoltage protection
LCZSPTOV - 59N
Section 16 1MRK 506 369-UUS -
Scheme communication
784 Line distance protection REL670 2.2 ANSI
Application manual
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