10 Abbreviations and symbols
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10. Abbreviations and symbols
American National Standards Institute. A
standardization organisation.
Circuit breaker failure protection
Active power divided by apparent power = P/S. (See power
factor PF). Negative sign indicates reverse power.
Nominal primary value of current transformer
Nominal secondary value of current transformer
Digital output, output relay
Data set ready. An RS232 signal. Input in front panel
port of VAMP relays to disable rear panel local port.
Daylight saving time. Adjusting the official local time
forward by one hour for summer time.
Data terminal ready. An RS232 signal. Output and
always true (+8 Vdc) in front panel port of VAMP relays.
Fast Fourier transform. Algorithm to convert time
domain signals to frequency domain or to phasors.
I.e. dead band. Used to avoid oscillation when comparing
two near by values.
Nominal current of the I
01
input of the relay
Nominal current of the I
02
input of the relay
Nominal current of I
0
input in general
Nominal current. Rating of CT primary or secondary.
International Electrotechnical Commission. An
international standardization organisation.
Institute of Electrical and Electronics Engineers
Abbreviation for communication protocol defined in
standard IEC 60870-5-103
Local area network. Ethernet based network for
computers and relays.
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.
Network time protocol for LAN and WWW
Per unit. Depending of the context the per unit refers to
any nominal value. For example for overcurrent setting 1
pu = 1xI
GN
.
Simple Network Time Protocol for LAN and WWW
Total harmonic distortion
Coordinated Universal Time (used to be called GMT =
Greenwich Mean Time)
World wide web internet
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