ABB RELION REX640, Техническое руководство, Страница: 576 / 1960

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
Blocking mode.
The
Blocking mode setting has three blocking methods. In the "Freeze timers"
mode, the operate timer is frozen to the prevailing value. 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
output is not activated.
If the
BLOCK
input of MFADPSDE is used in the configuration, then "Block
all" mode is recommended.
Recommended uses of the
BLOCK
input of MFADPSDE are:
1. Connecting the start signal of non-directional earth fault protection (EFxPTOC),
set to operate in case of a cross-country fault, to
BLOCK
input of MFADPSDE
to reset phasor accumulation during a cross-country fault. MFADPSDE can then
adapt to a fault direction change more rapidly if a single-phase earth fault
persists in the system after the other faulty feeder has been tripped (the cross-
country fault has been transformed into a single-phase earth fault).
2. Connecting the ‘Auto-Reclose in progress’ output (
INPRO
) from DARREC to
BLOCK
input of MFADPSDE to allow faster reset of MFADPSDE during high-
speed auto-reclosing cycle HSAR when setting
Reset delay time equals or is
higher than the dead time of high-speed auto-reclosing cycle HSAR.
3. In case of a network with distributed coils but no centralized arc suppression
coil at the primary substation (unearthed network), it is recommended to add
an additional logic to protection configuration, which blocks MFADPSDE if the
frequency of measured Uo and Io becomes lower than nominal. Such condition
is valid in network when earth fault becomes disconnected and a phenomenon
called ‘post-fault oscillation’ is initiated.
4. If the parallel resistor of the coil has long connection delay, it is recommended
to add an additional logic to protection configuration to enable the release of
MFADPSDE at the time of the parallel resistor switching.
The logic to release MFADPSDE at time of resistor (re)connection is illustrated in
Figure 332 .
• Detection of earth fault from residual overvoltage, ROVPTOV
• Delay of release MFADPSDE using TONGAPC connected to the
BLOCK
input of
MFA (inversed)
• Delay of release (TONGAPC: On delay time (ms)) based on known time delays in
resistor connection
• Protection operate delay time to be set smaller than the resistor connection
duration.
Protection functions 1MRS759142 F
576 REX640
Technical Manual