Sel 751A - Glossary

Date Code 20100129 Instruction Manual SEL-751A Relay
Glossary
R.Instruct ion Manual
A
Abbreviation for amps or amperes; units of electrical current magnitude.
ACSELERATOR
QuickSet
®
SEL-5030
Software
A Windows
®
-based program that simplifies settings and provides analysis
support.
ACSELERATOR Archi-
tect
®
SEL-5032 Software
Design and commissioning tool for IEC 61850 communications.
Ambient Temperature
Temperature of the motor cooling air at the cooling air inlet. Measured by an
RTD whose location setting is AMB.
Analog
In this instruction manual, Analog is synonymous with Transducer.
ANSI Standard
Device Numbers
A list of standard numbers used to represent electrical protection and control
relays. The standard device numbers used in this instruction manual include:
25 Synchronism Check Element
27 Undervoltage Element
49 Thermal Element
50 Instantaneous Overcurrent Element
51 Inverse Time-Overcurrent Element
52 AC Circuit Breaker
55 Power Factor Element
59 Overvoltage Element
79 Reclosing Control Logic
81 Frequency Element
81R Rate-of-Change of Frequency Element
These numbers are frequently used within a suffix letter to further designate
application. The suffix letters used in this instruction manual include:
P Phase Element
G Residual/Ground Element
N Neutral/Ground Element
Q Negative-Sequence (3I2) Element
Apparent Power, S
Complex power expressed in units of volt-amps (VA), kilovolt-amps (kVA), or
megavolt-amps (MVA). Accounts for both real (P) and reactive (Q) power dis-
sipated in a circuit: S = P + jQ.
Arc-Flash Detection
The sensing of an arc-flash condition by detection of light and overcurrent by
the relay.
Bare-Fiber Sensor—The fiber optic loop sensor used for arc-flash
detection.
Point Sensor—The fiber-optic cable sensor with a light diffuser on the
end and used for arc-flash detection.
Arc-Flash Protection
(Relay)
An action performed by the relay to minimize the arc-flash hazard.