GL.4
SEL-587Z Relay
Date Code 20020903
Glossary
CVT
—
ESD (Electrostatic Discharge)
CVT
Capacitive voltage transformer that uses a capacitive voltage divider to reduce
transmission voltage to a level safe for metering and relaying devices. See
CCVT.
Data Bit
A single unit of information that can assume a value of either logical 0 or
logical 1 and can convey control, address, information, or frame check
sequence data.
DC Offset
A dc component of fault current that results from the physical phenomenon
preventing an instantaneous change of current in an inductive circuit.
DCE Devices
Data communication equipment devices (modems).
Deassert
To deactivate. To remove the logic or electrical requirements needed to
operate a device. To clear a logic condition to its false state (logical 0). To
open the circuit or open the contacts across an SEL-587Z Relay input. To open
a normally open output contact. To close a normally closed output contact.
Debounce Time
The time that masks the period when relay contacts continue to move after
closing; debounce time covers this indeterminate state.
Delta
A phase-to-phase series connection of circuit elements, particularly voltage
transformers or loads.
Demand Meter
A measuring function that calculates a thermal average of instantaneous
measurements over time.
Differential Protection
A protection scheme that responds to the difference between incoming and
outgoing electrical quantities, usually currents.
DMTC Period
The time of the demand meter time constant in demand metering.
Dropout Time
The time measured from the removal of an input signal until the output signal
deasserts. You can set the time, in the case of a logic variable timer, or the
dropout time can be a result of the characteristics of an element algorithm, as
in the case of an overcurrent element dropout time.
DTE Devices
Data terminal equipment (computers, terminals, printers, relays, etc.).
Dumb Terminal
See ASCII terminal.
EEPROM
Electrically Erasable Programmable Read-Only Memory. Nonvolatile
memory where relay settings, event reports, SER records, and other
nonvolatile data are stored.
EHV
Extra high voltage. Voltages greater than 230 kV.
EIA-232
Electrical definition for point-to-point serial data communications interfaces,
based on the standard EIA/TIA-232. Formerly known as RS-232.
EIA-485
Electrical standard for multidrop serial data communications interfaces, based
on the standard EIA/TIA-485. Formerly known as RS-485.
Electromechanical Reset
Setting of the relay to match the reset characteristics of an electromechanical
overcurrent relay.
ESD
(Electrostatic Discharge)
The sudden transfer of charge between objects at different potentials caused
by direct contact or induced by an electrostatic field.
Содержание SEL-587Z
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