Rockwell Automation 865 Differential Protection Relay - Manual (Page 181)

Chapter
11
865-UM001A-EN-P – July 2009
Abbreviations and Symbols
ANSI American National Standards Institute. A standardization
organization.
CB Circuit breaker
CBFP Circuit breaker failure protection
cos
ϕ Active power divided by apparent power = P/S. (See power factor
PF). Negative sign indicates reverse power.
CT Current transformer
CT
PRI
Nominal primary value of current transformer
CT
SEC
Nominal secondary value of current transformer
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
01N
Nominal current of the I
01
input of the relay
I
02N
Nominal current of the I
02
input of the relay
I 0N Nominal current of I 0 input in general
I
N
Nominal current. Rating of CT primary or secondary.
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