ABB RELION REX640 Technical Manual page 1141

1MRS759142 C
REX640
Technical Manual
The AR control module blocks the Zone acceleration module after the
initiation of the first shot until the AR sequence has been completed,
that is, until the AR_READY input signal changes its state back from
FALSE to TRUE.
Zone acceleration
The start signal from the overreaching zone whose operation is to be accelerated is
connected to the EX_ACC input. When the EX_ACC input is activated and,
simultaneously, the AR control module gives permission for acceleration, the operate
signal from Zone extension logic is obtained from the OPR_Z_EXTN output, which is
used to trip the circuit breaker and initiate the autoreclosing (the AR shot).
The activation of the BLOCK input blocks the OPR_Z_EXTN output.
Loss of load logic
Loss of load logic is enabled with Operation mode = "Loss of load".
When the loss of load operation mode is enabled, a time-delayed overreaching zone
is allowed to trip instantaneously if the loss of load current condition is detected.
The loss of load function does not operate in case of a three-phase fault
as all the phases are faulty. Therefore, none of the current values drops
below the Minimum current setting, meaning that the loss of load
current condition cannot be detected.
Loss of load logic can be described using a module diagram.
I3P
LOSSLOAD_ACC
CB_CL_CMD
BLOCK
GUID-200B5A32-0B28-47E9-B54B-0DE9CE3C36A3 V1 EN
Figure 614: Functional module diagram of Loss of load logic
Initialization
The Initialization module gives an enabling signal to the Trip logic module when the
values of all three phase currents are above the set value of Load current value for
Protection related functions
I_A
I_B
Initialization
I_C
Loss of load
current
detection
Section 5
OPR_LOSSLOAD
Trip logic
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