Glossary
77
demand
The measurement and summation of current or energy
over a specified time, typically 15 or 30 minutes.
demand period
The specified time, typically 15 or 30 minutes,
over which current or energy data is collected and from which the
demand value is calculated.
device address
See
Address
.
DLY
Time delay (value).
display contrast
A setting that can be adjusted to increase or
decrease the contrast of the panel display.
E
EIA
Electronic Industries Association.
EIA-232
See
RS-232.
EIA-485
See
RS-485
.
Electronic Bell Alarm
Accessory that attaches to the trip unit
and provides a solid-state relay contact for remote indication of
breaker tripping.
EP
Expansion Plug.
event log
A record of faults and alarms, including the date and
time they occurred.
Expansion Plug
Interface between the trip unit and the Multi-
plexer Translator for zone interlocking.
extended protective relaying
See
Protective Relay Functions
.
external neutral sensor
The current transformer located on
the neutral bus of a four-wire electrical system.
external power supply
An AC/DC converter which supplies
power for the trip unit’s metering and communications functions.
F
fault
Electrical disturbance such as a short circuit or open cir-
cuit.
fault counter
The counter on the trip unit that records breaker
operations.
fixed delay
A trip time delay that is a constant value, regardless
of the magnitude of the overcurrent.
frame size
See
Breaker Frame Size
.
G
GF
ground fault (protection).
ground fault mode switch
The switch on the side of the trip
unit that selects the ground fault sensing scheme, either Residual
(all three phases added) or Ground Return.
ground fault protection
Protection against shorts to ground.
ground overcurrent alarm
An alarm activated by current in
the ground line exceeding a set limit.
ground return
The ground fault sensing scheme in which the
ground fault sensor is located at the neutral connection to
ground.
H
harmonic analysis
Mathematical analysis of a waveform to
determine its harmonic components.
I, J
ICCB
Insulated Case Circuit Breaker.
idle display mode
The trip unit’s mode of operation when left
idle for five minutes or longer. The display shows several screens
of data and configuration settings in sequence until a key on the
keypad is pressed. Remote configuration of the trip unit is allowed
only while it is in this mode. It is also available from the View Data
selection on the main menu.
IEC
International Electrotechnical Committee. The international
standards organization for electrical and electronic equipment.
I
n
Rating Plug value.
I
2
t
A variable time delay in which the delay is progressively
shorter as the overcurrent value increases. I
2
t describes the rela-
tionship between the overcurrent magnitude and time.
INST
Instantaneous fault (protection).
instantaneous
Overcurrent protection that occurs immediately,
without any delay.
