Sel 411L - Section 1: Introduction and Specifications

Date Code 20151029 Protection Manual SEL-411L Relay
Section 1
P.Protection Manual
Introduction and Specifications
The relay is a high-speed transmission line differential, distance, and current
protection relay featuring single-pole and three-pole tripping and reclosing
with synchronism check, circuit breaker monitoring, circuit breaker failure
protection, and series-compensated line protection logic. The relay features
extensive metering and data recording including high-resolution data capture
and reporting.
The 87L function of the relay provides protection for any transmission line or
cable with as many as three terminals over serial communications, and as
many as four terminals over Ethernet, in three-pole or single-pole tripping
modes. Each terminal can be connected in a dual-breaker arrangement. The
relay applies a generalized Alpha Plane algorithm that you can use for such
applications as multiple currents in the differential zone, applications with
harmonic restraint or blocking for in-line transformers and line-charging
current compensation.
Phase-segregated (87LP), negative-sequence (87LQ), and zero-sequence
(87LG) differential elements use patented generalized Alpha Plane
comparators. Combined with overcurrent supervision, external fault detection,
optional charging current compensation, and disturbance detection logic the
87L function operates with exceptional security and sensitivity.
The relay allows for in-line power transformer applications by compensating
for transformer vector group, ratio, and zero-sequence current. The 87L
function supports harmonic blocking and/or harmonic restraint for
stabilization during transformer inrush conditions. During overexcitation
conditions, the relay uses fifth-harmonic current to secure the 87L elements.
The 87L function can protect multiwinding transformers.
Line-charging current compensation enhances sensitivity of the 87L elements
in applications of the relay for protection of long, extra high-voltage lines or
cables. Charging current is calculated using the measured line terminal
voltages. This value is then subtracted from the measured phase current. This
compensation method results in accurate compensation for both balanced and
unbalanced system conditions. This method works for line pickup even when
uneven breaker operation occurs. The line-charging current algorithm has
built-in fallback logic in the event of an LOP condition.
The relay features expanded SEL
OGIC
®
control equation programming for
easy and flexible implementation of custom protection and control schemes.
The relay has separate protection and automation SEL
OGIC control equation
programming areas with extensive protection and automation programming
capability.
The relay provides extensive communications interfaces from standard SEL
ASCII and enhanced M
IRRORED BITS
®
communications protocols to Ethernet
connectivity with the optional Ethernet card. With the Ethernet card, you can
employ the latest industry communications tools, including Telnet, FTP, IEC
61850, and DNP3 (serial and LAN/WAN) protocols.