ABB RELION REX640 Technical Manual page 945

1MRS759142 F
Earth-fault detection function
Directional function for earth faults
Fault loop selection and back-up protection
Cross-country fault detection function for
high-impedance earthed networks
Phase preference logic for high-impedance
earthed networks
Fault loop selection logic for low-impedance
earthed networks
Figure 525: Main functionality of DSTPDIS
All outputs and the operation of all sub-functions can be blocked with the BLOCK
binary input signal. In addition, it resets the timers.
Blocking
There are three operation modes in the blocking function. The operation modes
are controlled by the BLOCK input and the global setting in Configuration >
System > Blocking mode which selects the blocking mode. The BLOCK input can
be controlled by a binary input, a horizontal communication input or an internal
signal of the protection relay's program. The influence of the BLOCK signal activation
is preselected with the global setting
The
timers" mode, the operation timer is frozen to the prevailing value, but the
OPERATE_Z1...5 output is not deactivated when blocking is activated. In the
"Block all" mode, the whole function is blocked and the timers are reset. In
the "Block OPERATE output" mode, the function operates normally but the
OPERATE_Z1...5 output is not activated.
In addition, the function has zone-specific blocking signals BLOCK_Z1...5. The
signal resets zone timers disabling the corresponding start and operate output
activation.
BLOCK_GFC deactivates START_GFC and OPERATE_GFC. It also resets GFC operate
time (set by
Earth-fault detection function
The recognition of an earth fault is an important part in identifying the correct fault
type. This information is used in faulted loop (phase) selection to release the correct
impedance-measuring elements. The earth-fault recognition is always required to
release the phase-to-earth impedance-measuring elements.
The earth-fault detection is indicated with the EARTH_FLT monitored data. The
earth-fault detection criterion can be defined with the
setting. The fundamental criterion is based on the residual current. The residual
voltage and reference neutral current, measured from the transformer neutral point,
can be used for the earth-fault detection criteria.
REX640
Technical Manual
General Fault Criteria (GFC)
Blocking mode setting has three blocking methods. In the "Freeze
Operate delay GFC ). Blocking does not prevent GFC operation.
Zone Z1
Zone Z2
Zone Z3
Blocking mode .
EF detection Mod GFC
Protection functions
Zone Z4
Zone Z5
945