VAMP 52 - 10. Abbreviations and symbols

10 Abbreviations and symbols Technical description
VM50.EN004 VAMP 24h support phone +358 (0)20 753 3264
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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
mode
Nominal current of the selected mode. In feeder mode, I
mode
=
VT
primary
. In motor mode, I
mode
= I
mot.
I
0n
Nominal current of I
0
input in general
I
mot
Nominal current of the protected motor
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-101
Abbreviation for communication protocol defined in
standard IEC 60870-5-101
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
P Active power. Unit = [W]
PF
Power factor. The absolute value is equal to cos
, but the
sign is '+' for inductive i.e. lagging current and '
' for
capacitive i.e. leading current.
P
M
Nominal power of the prime mover. (Used by reverse/under
power protection.)
PT See VT