4.196
SEL-751 Relay Instruction Manual Date Code 20170927
Protection and Logic Functions
Front-Panel Settings (SET F Command)
Following are examples of selected display point settings, showing the result-
ing front-panel displays. For example, at a certain station we want to display the
status of both HV and LV circuit breakers of Transformer 1. When the HV circuit
breaker is open, we want the LCD display to show:
TRFR 1 HV BRKR: OPEN,
and when the HV circuit breaker is closed, we want the display to show:
TRFR
1 HV BRKR: CLOSED
. We also want similar displays for the LV breaker.
After connecting a Form A (normally open) auxiliary contact from the HV cir-
cuit breaker to Input IN101 and a similar contact from the LV circuit breaker to
Input IN102 of the SEL-751, we are ready to program the display points, using
the following information for the HV breaker (LV breaker similar):
➤ Relay Word bit—IN101
➤ Alias—TRFR 1 HV BRKR:
➤ Set String—CLOSED (the form a [normally open] contact
asserts or sets Relay Word bit IN101 when the circuit breaker is
closed)
➤ Clear String—OPEN (the form a [normally open] contact
deasserts or clears Relay Word bit IN101 when the circuit
breaker is open)
Name, Alias, Set String, and Clear String
When all four strings have entries, the relay reports all states.
Table 4.92 Settings That Always, Never, or Conditionally Hide a Display Point
Programmable Automation
Controller Setting
Name Alias Set String Clear String Comment
DP01 := IN101, TRFR1, CLOSED, OPEN IN101 TRFR1 CLOSED OPEN Never hidden
DP01 := IN101, TRFR1 IN101 TRFR1 — — Never hidden
DP01 := NA — — — — Always hidden
DP01 := IN101,,, IN101 — — — Always hidden
DP01 := IN101, TRFR1,, IN101 TRFR1 — — Always hidden
DP01 := IN101, TRFR1, CLOSED, IN101 TRFR1 CLOSED — Hidden when IN101 is deasserted
DP01 := IN101, “TRFR 1”,, OPEN IN101 TRFR 1 — OPEN Hidden when IN101 is asserted
DP01 := 1,{} 1 {} — — Empty line
DP01 := 1,“Fixed Text” 1 Fixed Text — — Displays the fixed text
DP01 := 0 0 — — — Hides the display point
Table 4.93 Entries for the Four Strings
Name Alias Set String Clear String
IN101 TRFR 1 HV BRKR CLOSED OPEN
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