1-4
Introduction
Date Code 990714
SEL—2BFR, -2/BFR Instruction Manual
Independent phase current detectors, protection logic, and timers make the relay easy to apply on
both simple systems and more complicated breaker arrangements such as single-pole trip installa-
tions.
The SEL-2BFR Relay stores summaries of the 100 latest events in nonvolatile memory. These
summaries include event type, mechanical and electrical operating times, breaker energy, and
date and time of operation. Using this breaker history, you can monitor breaker wear and
effectively schedule routine breaker maintenance.
A breaker can occasionally operate incompletely, leaving trip or close resistors in service. The
energy dissipated in a breaker resistor due to current flow can exceed the resistor thermal rating
within seconds, resulting in dangerous and expensive resistor failure.
When potential transformer inputs are used, the SEL-2BFR Relay uses six thermal models to
monitor energy dissipated in breaker trip and close resistors. When a resistor temperature
estimate reaches preset limits, the relay can alarm, generate an event report, or trip the lockout
relay. Resistor thermal models have pending failure and failure temperature levels.
The thermal protection function does not require an initiating input; it monitors the breaker
continuously. Thermal protection can be disabled when trip and close resistors are not used.
When you use a single motor-operated disconnect switch (MOD) with the protected breaker, the
SEL-2BFR Relay can trip the MOD to isolate the failed breaker when phase current drops below
a settable value. When an MOD is not installed, the MOD logic may be used to indicate a ‘Safe
to Disconnect’ condition to personnel.
The relay also includes Programmable Mask Logic, which allows you to configure the 86BF
TRIP and five auxiliary outputs to operate when any of 40 protective elements or logic outputs
pick up. You can implement complete application-specific protective schemes with a minimum
of wiring and panel space. Programmable Mask Logic also simplifies relay testing.
Communications functions provide remote and local examination of a wide range of data,
including the voltages and currents presented to the instrument, relay settings, and a history of
the last 100 events. You can enter and modify relay settings remotely; you can also control all
outputs via the communications channel. A two-level password scheme protects settings and
circuit breaker control. The SEL-2BFR Relay monitors password execution and closes the
ALARM contact output to indicate possible unauthorized access. The relay requires no special
communication software. Access the relay with a dumb terminal, printing terminal, or computer
with serial port and terminal emulation software.
A wide range of user-selectable events, including any input or output assertion (except ALARM),
triggers the event record function. Assertion of the 86BF TRIP output automatically generates an
event report. You can also set the relay to trigger an event report for CLOSE or TRIP input
assertions. This ensures a record of every normal circuit breaker operation, as well as every
circuit breaker failure (
Section 4: Event Reporting
includes more details on triggering event
reports).
The event report contains all information needed to determine the cause of relay and breaker
operations. These 15-cycle reports contain current, voltage, input, output, and relay element data
presented on a quarter-cycle basis. Parameters such as event type, relay response time, circuit
breaker operation time, currents, voltages, and breaker power dissipation appear directly in the
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