Thermal Overload Blocking - ABB RELION REX640 Technical Manual

Section 9
Control functions
9.9.3.4
9.9.4
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GUID-BF55C146-A39B-458D-BC55-C26240702150 V1 EN
Figure 788: Master and slave scheme
If the AR unit is defined as a master by setting its terminal priority to high:
• The unit activates the CMD_WAIT output to the low priority slave unit whenever
a shot is in progress, a reclosing is unsuccessful or the BLK_RCLM_T input is
active
• The CMD_WAIT output is reset one second after the reclose command is given or
if the sequence is unsuccessful when the reclaim time elapses.
If the AR unit is defined as a slave by setting its terminal priority to low:
• The unit waits until the master releases the BLK_RECL_T input (the CMD_WAIT
output in the master). Only after this signal has been deactivated, the reclose time
for the slave unit can be started.
• The slave unit is set to a lockout state if the BLK_RECL_T input is not released
within the time defined by the Max wait time setting , which follows the initiation
of an autoreclosing shot.
If the terminal priority of the AR unit is set to "none", the AR unit skips all these
actions.

Thermal overload blocking

An alarm or start signal from the thermal overload protection (T1PTTR) can be routed
to the input BLK_THERM to block and hold the reclose sequence. The BLK_THERM
signal does not affect the starting of the sequence. When the reclose time has elapsed
and the BLK_THERM input is active, the shot is not ready until the BLK_THERM input
deactivates. Should the BLK_THERM input remain active longer than the time set by
the setting Max Thm block time, the AR function goes to lockout.
If the BLK_THERM input is activated when the auto wait timer is running, the auto
wait timer is reset and the timer restarted when the BLK_THERM input deactivates.
Operation principle
The function can be enabled and disabled with the Operation setting. The
corresponding parameter values are "on" and "off". Setting Operation to "off" resets
non-volatile counters.
The reclosing operation can be enabled and disabled with the Reclosing operation
setting. This setting does not disable the function, only the reclosing functionality. The
1MRS759142 C
REX640
Technical Manual