1MRS751802-MUM
REX 521
69
Protection Relay
Technical Reference Manual, Standard Configurations
4.4.
Other functions described in signal overview diagrams
4.4.1.
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.
Fig. 4.4.1.-1
Lockout function in the block diagrams of the standard
configurations
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.
Fig. 4.4.1.-2
The first option how to use the lockout function
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, for example PO1. This is
done by selecting lockout for the corresponding output signal selector.
3I>
3I>>
3I>>>
Io>-->
Io>>-->
Io>>>-->
Iub>
3Ith>
1
Lockout
Lockout
HSPO1
Lockout reset
S
Q
R
Lockout Working
HSPO1
≥
1
Master Trip
(X4.2.3/4/1/2)
≥
1
Trip 1
Lockout
Lockout
HSPO1
Lockout reset
S
Q
R
Lockout Working
≥
1
Lockout1
Trip
signal
HSPO1
(trip relay)
Selector
Connected to COCB
(Close enable)
to prevent
close operation
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