TERMINOLOGY
GENERAL
1TNC928250M0201
3
Abbreviation
Term
Description
RS485
Communication interface standard from EIA (Elec-
tronics Industries Association, USA), operating on
voltages between 0V and +5V. RS-485 is more
noise resistant than RS-232C, handles data trans-
mission over longer distances, and can drive more
receivers.
THD
Total harmonic dis-
tortion
It is defined as the ratio of the sum of the powers
of all harmonic components to the power of
the
P
Total active power of all phases
QA
Total reactive power calculated by arithmetic
method
QV
Total reactive power calculated by vector method
SA
Total apparent power calculated by arithmetic
method
SV
Total apparent power calculated by vector method
Ea
Total active energy
ErA
Total reactive energy arithmetic
EapV
Total apparent energy vector
EapA
Total apparent energy arithmetic
F
Frequency
Value of measured frequencies in an electrical dis-
tribution system
I
Phase current
Value of the current flowing in each phase of an
electrical distribution system
I
N
Measured neutral
current
Value of neutral current of an electrical distribu-
tion system
I
NC
Calculated neutral
current
Value of neutral current of an electrical distribu-
tion system by calculate
U
Voltage
Voltage including Upg (line p to line g voltage) and
Vp (line p to neutral voltage)
PF
A
Power factor Arith-
metic
Under periodic conditions, ratio of the absolute
value of the active power to the apparent power
