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Technical description
10 Abbreviations and symbols
VM265.EN011
VAMP 24h support phone +358 (0)20 753 3264
213
10.
Abbreviations and symbols
ANSI
American National Standards Institute. A
standardization organisation.
CB
Circuit breaker
CBFP
Circuit breaker failure protection
cos
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 VAMP 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 VAMP 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 organisation.
IEEE
Institute of Electrical and Electronics Engineers
IEC-103
Abbreviation for communication protocol defined in
standard IEC 60870-5-103
LAN
Local area network. Ethernet based network for
computers and relays.
Latching
Output relays and indication LEDs can be latched, which
means that they are not released when the control signal
is releasing. Releasing of lathed devices is done with a
separate action.
NTP
Network time protocol for LAN and WWW
pu
Per unit. Depending of the context the per unit refers to
any nominal value. For example for overcurrent setting 1
pu = 1xI
GN
.
RMS
Root mean square
SNTP
Simple Network Time Protocol for LAN and WWW
TCS
Trip circuit supervision
THD
Total harmonic distortion
UTC
Coordinated Universal Time (used to be called GMT =
Greenwich Mean Time)
WWW
World wide web
internet
Summary of Contents for 265
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