SEL-411L Data Sheet Schweitzer Engineering Laboratories, Inc.
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➤
Charging Current Compensation. Line charging current compensation enhances sensitivity of the 87L elements
in applications for protection of long, extra high voltage lines or cables. Charging current is calculated by using the
measured line terminal voltages and is then subtracted from the measured phase current. This compensation
method results in accurate compensation for both faulted and non-faulted system conditions. The line charging
current algorithm has built-in fallback logic in the event of an LOP condition.
➤ External Fault Detector. An external fault detection algorithm secures the 87L elements against CT errors when
the algorithm detects one of the two following conditions:
➢ An increase in the through current of the protected zone that is not accompanied by an increase in the
differential current of the protected zone (typical of an external fault)
➢ The dc component of any current exceeds a preset threshold compared with the ac component without the
differential current having a significant change (typical when energizing a line reactor or a power transformer)
➤ Stub Bus Protection. Disconnect status inputs and voltage elements can enable high-speed stub bus protection
and proper response toward remote SEL-411L relays. Stub bus protection in the SEL-411L provides a true restrained
differential function that yields exceptional security in dual-breaker applications.
➤ 87L Communications Protocols Supported. The SEL-411L allows serial 87L communication over direct point-
to-point fiber, IEEE C37.94 multiplexed fiber, EIA-422, and G.703 media.
➤ Data Synchronization. The relay allows for synchronizing data exchanged between relays based on the channel (for
symmetrical channels) or using external time sources for applications over Ethernet or asymmetrical channels.
Selecting the synchronization method is on a per-channel basis. If you use external time sources, the SEL-411L
provides built-in fallback logic to deal with any loss or degradation of such sources.
➤ Broken Conductor Detection (BCD). The optional BCD function can detect a broken conductor over the length of
the protected line to help mitigate possible fire or public hazard. The BCD element is designed for multiterminal
overhead or hybrid lines, including tapped line configurations to detect a conductor break before it converts into a
shunt fault.
➤ Complete Distance Protection. You can apply as many as five zones of phase and ground distance and directional
overcurrent elements. Select mho or quadrilateral characteristics for any phase or ground distance element. Use the
optional high-speed distance elements and series-compensation logic to optimize protection for critical lines. Patented
coupling capacitor voltage transformer (CCVT) transient overreach logic enhances the security of Zone 1 distance
elements. Best Choice Ground Directional Element
®
logic optimizes directional element performance and
eliminates the need for many directional settings. Apply the distance and directional elements in communications-
based protection schemes, such as POTT, DCB, and DCUB, or for instantaneous or time-step backup protection.
➤ Power Swing Blocking and Out-of-Step Tripping. You can select power swing blocking of distance elements for
stable power swings or out-of-step tripping for unstable power swings. A zero-setting, out-of-step detection logic is
available, eliminating the need for settings and extensive power system studies.
➤ Synchronism Check. Synchronism check can prevent circuit breakers from closing if the corresponding phases
across the open circuit breaker are excessively out of phase, magnitude, or frequency. The synchronism-check
function has a user-selectable synchronizing voltage source and incorporates slip frequency, two levels of maximum
angle difference, and breaker close time into the closing decision.
➤ Reclosing Control. You can incorporate programmable single-pole or three-pole trip and reclose of one or two
breakers into an integrated substation control system. Synchronism and voltage checks from multiple sources
provide complete bay control.
➤ High-Accuracy Traveling-Wave Fault Locator. On two terminal lines with a high-accuracy time source, the
SEL-411L achieves the highest possible fault location accuracy with a double-ended traveling-wave (TW) algorithm.
A dedicated analog-to-digital converter samples currents at 1.5625 MHz and extracts high-frequency content to
calculate fault location.
➤ Advanced Multiterminal Fault Locator. Utilities can efficiently dispatch line crews to quickly isolate line
problems and restore service faster. For two-terminal lines, data are used from each terminal to achieve highly
accurate fault location with a traveling-wave algorithm and with an impedance-based fault location estimate. For
three-terminal lines, the relay accurately locates faults by using data from each terminal to compute a three-
terminal impedance-based fault location estimate and correctly identifies a faulted line segment. Upon loss of
communication or degraded data synchronization, the relay returns to a single-ended method, always providing
valuable fault location results to aid inspection and repair. The SEL-411L displays the traveling-wave and best
available impedance-based fault location estimates for each fault.
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