Other Functions Described In Signal Overview Diagrams; Lockout Function - ABB REX 521 Technical Reference Manual, Standard Configurations

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4.4.
4.4.1.
Protection Relay
Technical Reference Manual, Standard Configurations

Other functions described in signal overview diagrams

Lockout function

The lockout function is used for increasing the safety when performing control
operations. Lockout function can be reset by using the input selector to connect one
of the digital inputs (DI1...DI9) to the Lockout reset signal.
Note that the trip indication LED cannot be cleared with push buttons [C] or [C] +
[E] until lockout reset occurs.
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Master Trip
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Trip 1
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In the figure above (Fig. 4.4.1.-1) the Lockout working signal is connected internally
to the CLOSEENA input of the COCB function block in order to activate the
interlocking. This means that it is not allowed to perform control operations in case
the lockout function is active.
The lockout function can be used in two different ways:
The first option is to use the HSPO1 output to perform the lockout function. The
"Lockout HSPO1" selector is used for activating the forced latching. The latched
output relay can only be reset via a digital input. The idea is to have an external
switch which needs to be reset before the CB close operation is allowed. For
example, a motor feeder has tripped and it is necessary to avoid the re-energising of
the motor before its temperature has cooled down to an acceptable level.
Trip
signal
S
R
Lockout reset
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Another option (see Fig. 4.4.1.-3) is to use the lockout function to connect the CB
close control wiring in series with one of the power output relays by selecting
lockout signal as an option for the desired output relay, e.g. PO1. This is done by
selecting lockout for the corresponding output signal selector.
≥1
S
Q
Lockout reset R
≥1
(trip relay)
Lockout
HSPO1
Q
Lockout Working
Selector
REX 521
HSPO1
(X4.2.3/4/1/2)
≥1
Lockout
HSPO1
Lockout Working
1
Lockout
HSPO1
Connected to COCB
(Close enable)
to prevent
close operation
59