Schweitzer Engineering Laboratories SEL-700G Series, Instruction Manual

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GL.5
Date Code 20170814 Instruction Manual SEL-700G Relay
Glossary
RAM — SEL
OGIC
Control Equation
RAM Abbreviation for Random Access Memory. Volatile memory where the relay
stores intermediate calculation results, Relay Word bits, and other data that are
updated every processing interval.
Rate-of-Change of
Frequency Element
A protection element that causes the relay to trip when the measured electrical
system rate of change of frequency exceeds a settable rate.
Relay Word
The collection of relay element and logic results. Each element or result is
represented by a unique identifier, known as a Relay Word bit.
Relay Word Bit
A single relay element or logic result that the relay updates once each process-
ing interval. A Relay Word bit can be equal to either logical 1 or logical 0.
Logical 1 represents a true logic condition, picked up element, or asserted
contact input or contact output. Logical 0 represents a false logic condition,
dropped out element, or deasserted contact input or contact output. You can
use Relay Word bits in SEL
OGIC
control equations to control relay tripping,
event triggering, and output contacts, as well as other functions.
Remote Bit A Relay Word bit for which state is controlled by serial port commands,
including the CONTROL command, binary Fast Operate command, or
Modbus command.
Residual Current
The sum of the measured phase currents. In normal, balanced operation, this
current is very small or zero. When a ground fault occurs, this current can be
large.
Restricted Earth Fault
Element (REF)
Restricted Earth Fault (REF) element provides sensitive protection against
ground faults in wye-connected generator winding. The element is “restricted”
in the sense that protection is restricted to ground faults within a zone defined
by neutral and terminal CT placement.
RMS Abbreviation for Root-Mean-Square. Refers to the effective value of the sinu-
soidal current and voltage measured by the relay, accounting for the funda-
mental frequency and higher order harmonics in the signal.
ROM
Abbreviation for Read-Only Memory. Nonvolatile memory where the relay
firmware is stored.
RTD Abbreviation for Resistance Temperature Device. An RTD is made of a metal
having a precisely known resistance and temperature coefficient of resistance.
The SEL-700G (and the SEL-2600 RTD Module) can measure the resistance
of the RTD, and thus determine the temperature at the RTD location. Typically
embedded in the motor windings or attached to the races of bearings.
Transducer Device that converts the input to the device to an analog output quantity of
either current (±1, 2.5, 5, 10 and 20 mA, or 4–20 ma), or voltage (±1, 2.5, 5, or
10 V).
Self-Test
A function that verifies the correct operation of a critical device subsystem
and indicates if an out-of-tolerance condition is detected. The SEL-700G is
equipped with self-tests that validate the relay power supply, microprocessor,
memory, and other critical systems.
SEL
OGIC
Control Equation
A relay setting that allows you to control a relay function (such as an output
contact) by using a logical combination of relay element outputs and fixed
logic outputs. Logical AND, OR, INVERT, rising edge [/], and falling edge [\]
operators, plus a single level of parentheses are available to use in each control
equation setting.