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Abbreviations and Symbols
ANSI
American National Standards Institute. A standardization
organization.
CB
Circuit breaker
CBFP
Circuit breaker failure protection
Active power divided by apparent power = P/S. (See power factor PF).
cosϕ
Negative sign indicates reverse power.
CT
Current transformer
CT
Nominal primary value of current transformer
PRI
CT
Nominal secondary value of current transformer
SEC
Dead band
See hysteresis.
DI
Digital input
DO
Digital output, output relay
DSR
Data set ready. An RS232 signal. Input in front panel port of Allen-
Bradley relays to disable rear panel local port.
DST
Daylight saving time. Adjusting the official local time forward by
one hour for summer time.
DTR
Data terminal ready. An RS232 signal. Output and always true (+8
Vdc) in front panel port of Allen-Bradley relays.
FFT
Fast Fourier transform. Algorithm to convert time domain signals to
frequency domain or to phasors.
Hysteresis
I.e. dead band. Used to avoid oscillation when comparing two near
by values.
I
Nominal current of the I
01N
I
Nominal current of the I
02N
I
Nominal current of I
0N
I
Nominal current. Rating of CT primary or secondary.
N
IEC
International Electrotechnical Commission. An international
standardization organization.
IEEE
Institute of Electrical and Electronics Engineers
IEC-103
Abbreviation for communication protocol defined in standard IEC
60870-5-103
input of the relay
01
input of the relay
02
input in general
0
11
Chapter
857-UM001A-EN-P – July 2009
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