Hitachi Relion 670 Series Applications Manual page 107

1MRK506375-UEN Rev. N
t6L2: An additional time delay to trip phase L2 if the phase preference is set to trip phase L2 in zone
6. The default setting is 0.0s.
U0Min: To check the minimum residual voltage on phase L1 if the start signal falls back, and
indicates the fault on phase L2 is cleared successfully. The default value is 50% UBase.
tVL2: To extend the time for phase L2 to check the voltage shift. For the times from t0L2 to t6L2, a
settable time tVL2 (operation time extension L2) is added. When a cross country fault occurs and the
phase L1 has tripped, wait for some time to ensure that:
• The fault on phase L2 is cleared successfully
• The voltage on phase L2 has recovered
• The distance and residual protection functions have reset.
OpModetGL2: For Off/On operation of an additional timer tGL2 used in the compensated earthed
network. The default setting is On.
tGL2: An additional time delay to trip L2 in compensated earthing. If the start signal continues to be
active, trip is given after expiration tPEZx plus tGL2. The default setting is 0.6 s.
dUOverdt: The rate of change of voltage for phase L1 and phase L2. When the priority L1 before L2
is selected, the time steps t1L2, t2L2, t3L2, t4L2, t5L2 and t6L2 are extended by tVL2. During trip
time of the corresponding zone, a normalization of the supply voltage can be identified (that is,
dUL1/dt < dUOverdt and dUL2/dt> dUOverdt). If a restrike of the earth fault is detected during the
tVL2 time (that is, dUL1/dt > dUOverdt, dUL2/dt < dUOverdt), an instantaneous trip will be issued.
Calculation of algorithm for both voltage step functions dUL1/dt and dUL2/dt is set with a common
parameter dUOverdt. The default setting is 100 V/s.
Stub line
ModeStubLine: To enable/disable the compensated network contains a stub line.
UPPMin: The minimum phase-to-phase voltage in %UB in case of a stub line. This is considered
before deciding to trip the line that has lower phase-to-earth voltage. The default setting is 80% UB.
tI0Stub: Time delay to trip for residual current in case of a stub line. The default setting is 0.2s.
KU: The phase-to-earth voltage ratio in case of a stub line.
7.2.3.2 Solidly earthed systems
In directly earthed networks, a distinction is made between the following types of faults:
• Double phase-to-phase fault, earthed or unearthed
• Single phase-to-earth fault
The fault currents are high during all short circuit events. In the event of high-resistance earth faults,
e.g. through trees, the earth current is low. These types of faults shall be detected and tripped
selectively by a sensitive earth-fault detection device in conjunction with protection signaling devices.
Setting guidelines
The settings for 2-phase Distance protection zones, quadrilateral characteristic (ZRWPDIS) are done
in primary values. The instrument transformer ratio that has been set for the analog input card is
used to automatically convert the measured secondary input signals to primary values used in
ZRWPDIS.
The default values given should be validated for each application and adopt the appropriate setting
values.
The parameters for ZRWPDIS are set via the local HMI or PCM600.
Railway application RER670
Application manual
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Section 7
Impedance protection
GUID-26B5547B-921E-47AE-B163-762F7F72DD68 v3
GUID-4665C835-19D1-4AF9-847C-E6D7D2568446 v2
GUID-F9BB43B1-7A1C-40A4-84DB-58ACE7B12C28 v2
101