ABB RELION REX640 Technical Manual page 1568

Section 9
Control functions
1562
If the Custom Man blocking setting is "Custom disabled", the blocking schema
regarding the active operation mode "Manual" or "Parallel manual" is given in
1417. Other operation modes follow the default schema.
Table 1417: Blocking schema for selection "Custom disabled"
Active Command Load
operation current
mode
Manual, Raise
Parallel
Lower
manual
Table 1418: Blocking schema for selection "OC, UV, EXT"
Active Command Load
operation current
mode
Manual, Raise
Parallel
Lower
manual
Table 1419: Blocking schema for selection "UV, EXT"
Active Command Load
operation current
mode
Manual, Raise
Parallel
Lower
manual
Load current
The load current blocking is mainly used for preventing the tap changer from
operating in an overcurrent situation. For example, if the current is not high enough to
activate the protection relay of the substation, it can still be fatal for the diverter switch
of the tap changer. This operation can be adjusted with the setting parameter Load
current limit. The maximum of measurements from the secondary-side current phases
is used for blocking. By default, both the automatic operation and the manual
operation are blocked (Table
The blocking status can be read from the output BLKD_I_LOD.
Block lowering voltage
The block lowering voltage feature blocks both raise and lower voltage commands if
the measured voltage is too low to be corrected by operating the tap changer. Such a
situation can occur due to a faulty measuring circuit, an earth fault or an overcurrent
situation. By default, only the automatic (also automatic follower) operation is
blocked when the undervoltage condition is met
adjusted with the setting parameter Block lower voltage.
Block lower Runback
voltage raise
voltage
x
Block lower Runback
voltage raise
voltage
x x x
x x
Block lower Runback
voltage raise
voltage
x x
x
1415) when the set limit is exceeded.
(Table
1MRS759142 C
High External Extreme
circulating block positions
current
High External Extreme
circulating block positions
current
x
x
High External Extreme
circulating block positions
current
x
x
1415). This operation can be
Technical Manual
Table
x
x
x
x
x
x
REX640