GL.17
Date Code 20020501
SEL-421/SEL-421-1 Relay
Glossary
Sequencing Timers
—
Strong Password
Sequencing Timers
Timers designed for sequencing automated operations.
Sequential Events
Recorder
A relay function that stores a record of the date and time of each assertion and
deassertion of every Relay Word bit in a list that you set in the relay. SER
provides a useful way to determine the order and timing of events of a relay
operation.
SER
Sequential Events Recorder or the relay serial port command to request a
report of the latest 1000 sequential events.
Series-Compensated Line
A power line on which the addition of series capacitance compensates for
excessive inductive line impedance.
Settle/Settling Time
Time required for an input signal to result in an unvarying output signal within
a specified range.
Shot Counter
A counter that records the number of times a recloser attempts to close a
circuit breaker.
Shunt Admittance
The admittance resulting from the presence of a device in parallel across other
devices or apparatus that diverts some current away from these devices or
apparatus.
Shunt Capacitance
The capacitance between a network connection and any existing ground.
Shunt Current
The current that a parallel-connected high-resistance or high-impedance
device diverts away from devices or apparatus.
SIN Operator
Operator in math SEL
OGIC
control equations that provides the sine function.
Single-Pole Trip
A circuit breaker trip operation that occurs when one pole of the three poles of
a circuit breaker opens independently of the other poles.
SIR
Source-to-line impedance ratio.
SOTF
(Switch-Onto-Fault
Protection Logic)
Logic that provides tripping if a circuit breaker closes into a zero voltage
bolted fault, such as would happen if protective grounds remained on the line
following maintenance.
Source Impedance
The impedance of an energy source at the input terminals of a device or
network.
SQRT Operator
Math SEL
OGIC
control equation operator that provides square root.
Stable Power Swing
A change in the electrical angle between power systems. A control action can
return the angular separation between systems to less than the critical angle.
Status Failure
A severe out-of-tolerance internal operating condition. The relay issues a
status failure message and enters a protection-disabled state.
Status Warning
Out-of-tolerance internal operating conditions that do not compromise relay
protection, yet are beyond expected limits. The relay issues a status warning
message and continues to operate.
Strong Password
A mix of valid password characters in a six-character combination that does
not spell common words in any portion of the password. Valid password
characters are numbers, upper- and lower-case alphabetic characters, “.”
(period), and “-” (hyphen).
Summary of Contents for SEL-421
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