ABB RELION REX640 Technical Manual

I_A
I_B
I_C
I3P
Distortion
measure-
ment
Total
harmonic
distortion
Total
demand
distortion
Harmonic
calculation
SMNTHD_A
SMNTHD_B
SMNTHD_C
SMNTDD_A
SMNTDD_B
SMNTDD_C
SMNDC_A
SMNDC_B
SMNDC_C
SMNH01_A
SMNH01_B
SMNH01_C
SMNH02_A
SMNH02_B
SMNH02_C
...unl hmax
Figure 960: Functional module diagram
10.1.5.1 Distortion measurement
The Distortion measurement module measures harmonics up to the 11
th
harmonic.
The filter used for harmonics includes a spectrum of frequencies near each
harmonic frequency. FFT for one period is used. The resulting frequency spectrum is
wider than in a harmonic subgroup. An anti-aliasing filter is used.
10.1.5.2 Total harmonic distortion
The total harmonic distortion THD is calculated from the measured harmonic
components with the formula
THD
I
I
h
h
n
=






=
∑
1
2
2
(Equation 390)
I
h
h
th
harmonic component
I
1
Fundamental frequency current (1
st
harmonic)
n Number of harmonics
1MRS759142 F Power quality measurement functions
REX640
Technical Manual
1809

ABB RELION REX640 Specifications

General

Model	RELION REX640
Category	Protection Device
Communication Protocols	IEC 61850, Modbus, DNP3, IEC 60870-5-103
Display	LCD
Rated Voltage	100-240 V AC/DC
Rated Frequency	50/60 Hz
Protection Functions	Overcurrent, Earth Fault, Overvoltage, Undervoltage, Frequency
Mounting	Rack mounting
Inputs/Outputs	Analog inputs
Housing	Metal
Input Voltage	24-250 V DC / 100-240 V AC
Operating Temperature	-25°C to +70°C
Enclosure	IP20