operate very quickly for faults very close to the generation (and relay) point, for which
very high fault currents are characteristic.
The instantaneous phase overcurrent protection PHPIOC (50) can operate in 10 ms for
faults characterized by very high currents.
9.1.3 Setting guidelines
The parameters for instantaneous phase overcurrent protection PHPIOC (50) are set via
the local HMI or PCM600.
This protection function must operate only in a selective way. So check all system and
transient conditions that could cause its unwanted operation.
Only detailed network studies can determine the operating conditions under which the
highest possible fault current is expected on the line. In most cases, this current appears
during three-phase fault conditions. But also examine single-phase-to-ground and two-
phase-to-ground conditions.
Also study transients that could cause a high increase of the line current for short times. A
typical example is a transmission line with a power transformer at the remote end, which
can cause high inrush current when connected to the network and can thus also cause the
operation of the built-in, instantaneous, overcurrent protection.
Common base IED values for primary current (IBase), primary voltage (UBase) and
primary power (SBase) are set in the global base values for settings function GBASVAL.
GlobalBaseSel: This is used to select GBASVAL function for reference of base values.
Operation: Set the protection to On/Off.
OpModeSel: This parameter can be set to 2 out of 3 or 1 out of 3. The setting controls the
minimum number of phase currents that must be larger than the set operate current Pickup
for operation. Normally this parameter is set to 1 out of 3and will thus detect all fault types.
If the protection is to be used mainly for multi phase faults, 2 out of 3 should be chosen.
Pickup: Set operate current in % of IB.
IP>>Max and IP>>Min should only be changed if remote setting of operation current
level, IP>>, is used. The limits are used for decreasing the used range of the IP>> setting.
If IP>> is set outside IP>>Max and IP>>Min, the closest of the limits to IP>> is used
by the function. If IP>>Max is smaller than IP>>Min, the limits are swapped.
MultPU: The set operate current can be changed by activation of the binary input
MULTPU to the set factor MultPU.
Section 9 1MRK 506 369-UUS -
Current protection
488 Line distance protection REL670 2.2 ANSI
Application manual
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