5-32 Trip and Target Logic Date Code 20001006
SEL-351 Instruction Manual
N Target LED
N target LED is illuminated at the rising edge of trip if a neutral ground overcurrent element
causes the trip.
79 Target LEDs
If the reclosing relay is turned off (enable setting E79 = N or 79OI1 = 0), all the Device 79
(reclosing relay) target LEDs are extinguished.
Target Reset/Lamp Test Front-Panel Pushbutton
When the Target Reset/Lamp Test front-panel pushbutton is pressed:
• All front-panel LEDs illuminate for one (1) second.
• All latched target LEDs (target LEDs numbered 2 through 13 in Table 5.1) are
extinguished (unlatched), unless a trip condition is present in which case the latched target
LEDs reappear in their previous state.
Other Applications for the Target Reset Function
Refer to the bottom of Figure 5.1. The combination of the TARGET RESET Pushbutton and the
TAR R (Target Reset) serial port command is available as Relay Word bit TRGTR. Relay Word
bit TRGTR pulses to logical 1 for one processing interval when either the TARGET RESET
Pushbutton is pushed or the TAR R (Target Reset) serial port command is executed.
Relay Word bit TRGTR can be used to unlatch logic. For example, refer to the breaker failure
logic in Figure 7.27 in Section 7: Inputs, Outputs, Timers, and Other Control Logic. If a
breaker failure trip occurs (SV7T asserts), the occurrence can be displayed on the front panel with
seal-in logic and a rotating default display (see Rotating Default Display in Sections 7 and 11,
also):
SV8 = (SV8 + SV7T)*!TRGTR
DP3 = SV8
DP3_1 = BREAKER FAILURE
DP3_0 = (blank)
Courtesy of NationalSwitchgear.com
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