2-12 Specifications Date Code 20000421
SEL-251, -2, -3 Instruction Manual
52AR or !52AR
If 52AR or !52AR is assigned to an input, not only does the input provide circuit
breaker status information, but it provides reclose initiation, too. The sensed transition
of the circuit breaker status, indicating that the circuit breaker is opening, initiates re-
closing. If the TRIP condition is present, it has to drop out before the open interval
starts timing.
In most applications, circuit breaker trips external to the relay (e.g., by control switch or
SCADA) must not cause reclose initiation. If input option RE (Reclose Enable) is
assigned to an input, the RE input is deenergized to prevent automatic reclosing. Cer-
tain control switch contacts can be wired to the RE input to defeat reclosing for control
switch trips.
Also, if 52AR or !52AR is assigned to an input, the circuit breaker status function is
time delayed by 10 cycles to qualify circuit breaker opening. This is done for certain
application needs (see System Restoration After Underfrequency Load Shedding sub-
section in Section 5: Applications). If this type of application is not needed, then it is
better to assign 52A or !52A to an input instead and avoid the 10-cycle time delay. This
time delay shows up in event reports and needs to be accounted for when making setting
52ADO.
The 10-cycle delay affects the circuit breaker monitor, too. The TDUR timer should be
set somewhat greater than 10 cycles so that relay initiated circuit breaker trips are
counted as such and not as external circuit breaker trips. Also, if an external trip occurs,
no interrupted current values will likely be accumulated by the circuit breaker monitor
because of the 10-cycle time delay.
Inputs IN5 and IN6 also appear directly in the Relay Word for use in the programmable logic.
Inputs IN1, IN2, and IN3 can be assigned to functions other than just SS1, SS2, and SS3,
respectively.
Assert an input by applying control voltage to the corresponding rear panel input terminals.
Control voltage polarity is not important. When a function is not assigned to an input, the relay
uses the respective default logic state shown above.
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