Sel 411L - Switch-Onto-Fault Logic

P.3.217
Date Code 20151029 Protection Manual SEL-411L Relay
Protection Functions
Switch-Onto-Fault Logic
Switch-Onto-Fault Logic
The switch-onto-fault (SOTF) logic permits specified protection elements to
trip for a settable time after the circuit breaker closes. Specify these elements
in the SEL
OGIC control equation TRSOTF (switch-onto-fault trip). The SOTF
logic works in two stages: validating a possible SOTF condition and initiating
(enabling) the SOTF protection duration.
The relay validates an SOTF condition by sensing the following.
➤ Upon circuit breaker opening: detection of a pole open
condition (3PO or SPO) when setting 52AEND (52A Pole
Open Qualifying Time Delay) is other than OFF
➤ Upon circuit breaker closing: detection of a pole open
condition (3PO or SPO) when setting CLOEND (CLSMON or
Single-Pole Open Delay) is other than OFF
Select either or both methods for the validating procedure.
The relay initiates SOTF protection at these corresponding instances.
➤ Circuit breaker opening: 52AEND timer timeout
➤ Circuit breaker closing: CLOEND time timeout and SELOGIC
control equation CLSMON assertion
Circuit Breaker
Opened SOTF Logic
Set ESOTF to Y and set 52AEND to other than OFF to enable the circuit
breaker-opened SOTF logic. When the circuit breaker opens, the 52AEND
timer operates when one or three poles open (SPO or 3PO assert). The logic
includes the SPO condition if setting ESPSTF := Y (see SOTF Options).
When the 3PO or SPO condition lasts longer than the 52AEND timer, the
relay asserts Relay Word bit SOTFE (SOTF Enable).
When the circuit breaker closes, either Relay Word bit 3PO deasserts after the
3POD dropout time or Relay Word bit SPO deasserts after the SPOD dropout
time. When 3PO or SPO deasserts, the relay continues to assert Relay Word
bit SOTFE for dropout time SOTFD or until the logic detects a healthy voltage
condition (if EVRST := Y, see SOTF Options).
Circuit Breaker
Closed SOTF Logic
You can detect circuit breaker close bus assertion by monitoring the dc close
bus. Connect a control input on the relay to the dc close bus. The control input
energizes whenever a manual close or automatic reclosure occurs. Set
SEL
OGIC control equation CLSMON (Close Signal Monitor) to monitor the
control input (e.g., CLSMON := IN202) and consequently detect close bus
assertion.
Set ESOTF to Y and set CLOEND to other than OFF to enable the circuit
breaker-closed SOTF logic. The CLOEND timer operates when one or three
poles open (SPO or 3PO asserts). If the 3PO or SPO condition continues
longer than the CLOEND time and the close bus asserts (SEL
OGIC control
equation CLSMON equals logical 1), Relay Word bit SOTFE asserts and
remains asserted for dropout time setting SOTFD or until the logic detects a
healthy voltage condition (if EVRST := Y, see SOTF Options).