“Prepare three-phase tripping” is then used to switch the tripping to three-phase. This signal
is generated by the auto recloser and connected to the trip function block and also connected
outside the IED through IO when a common auto recloser is provided for two sub-systems. An
alternative signal “Prepare 1-phase tripping” is also provided and can be used as an alternative
when the autorecloser is shared with another subsystem. This provides a fail safe connection
so that even a failure in the IED with the auto recloser will mean that the other sub-system will
start a three-phase trip.
A permanent fault will cause the line protection to trip again when it recloses in an attempt to
energize the line.
The auto reclosing function allows a number of parameters to be adjusted.
Examples:
• number of auto reclosing shots
• auto reclosing program
• auto reclosing dead times for each shot
12.2.2.1 Auto reclosing operation Off and On
M12391-91 v6
Operation of the automatic recloser can be set to Off and On by a setting parameter or by
external control. The setting parameter
Operation
=
Off
, or
On
sets the function to Off or On.
With the settings
Operation
=
On
and
ExternalCtrl
=
On
, the control is made by input signal
pulses to the inputs On and Off, for example, from a control system or by a control switch.
When the auto recloser is set On, the
SETON
output is set, and the auto recloser becomes
operative if other conditions such as circuit breaker is closed and circuit breaker is ready are
also fulfilled, the
READY
output is activated (high). Then the auto recloser is ready to accept a
start.
12.2.2.2 Start auto reclosing and conditions for start of a reclosing cycle
M12391-94 v5
The usual way to start an auto reclosing cycle, or sequence, is to start it at selective tripping by
line protection by applying a signal to the
START
input. Starting signals can be either, general
trip signals or, only the conditions for differential, distance protection zone 1 and distance
protection aided trip. In some cases also directional earth fault protection aided trip can be
connected to start an auto reclose attempt. If general trip is used to start the auto recloser it
is important to block it from other functions that should not start an auto reclosing sequence.
In cases where one wants to differentiate three-phase auto reclosing dead time, for different
power system configuration or at tripping by different protection stages, one can also use the
STARTHS
input (start high-speed reclosing). When initiating
STARTHS
, the auto reclosing dead
time for three-phase shot 1,
t1 3PhHS
is used and the closing is done without checking the
synchrocheck condition.
A number of conditions need to be fulfilled for the start to be accepted and a new auto
reclosing cycle to be started. They are linked to dedicated inputs. The inputs are:
•
CBREADY
, circuit breaker ready for a reclosing cycle, for example, charged operating gear.
•
CBCLOSED
to ensure that the circuit breaker was closed when the line fault occurred and
start was applied.
• No signal at
INHIBIT
input that is, no blocking or inhibit signal present. After the start has
been accepted, it is latched in and an internal signal “start” is set. It can be interrupted by
certain events, like an “inhibit” signal.
1MRK 505 370-UEN D Section 12
Control
Busbar protection REB670 267
Application manual
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