98 6LE008146B
Measurement functions
6.11 Accuracy of measurements
The precision of each measurement applies to a measurement range or extent in accordance
with IEC 61557-12. It is defined, in accordance with IEC 61557-12, for a power supply within
normal ambient temperature conditions of 23 °C ± 2 °C.
For a measurement taken at another temperature, within the temperature range of - 25 °C...+
70 °C, the temperature accuracy derating coecient is 0.05% per °C.
The accuracy range is the part of the measuring range for which the defined accuracy is
obtained; the definition of this range may be related to the load characteristics of the circuit
breaker.
Variables Symbols Measuring
range
Accuracy
class
according to
IEC 61557-12
Currents and Max./Min.
current
I1, I2, I3; IN, Iavg, Imax, Imin,… 0.2 x Ib ... Imax 0.5
Earth fault % IG 0.2 x Ib ... Imax 0.5
Current unbalance Inba1, Inba2, Inba3, InbaN, Inba - -
Phase-phase and Min/Max
voltages
U12, U23, U31, Uavg 120 V - 690 V 0.5
Phase-neutral and Min/Max
voltages
V1N, V2N, V3N, Vavg 70 V - 440 V 0.5
Unbalances U12 Unb, U23 Unb, U31 Unb, V1N
Unb, V2N Unb, V3N Unb, Max
Unb U, Max Unb V
0.8…1.2 x Vn -
Frequency f 45 Hz - 65 Hz 0.02
Power P total, P per phase, Q total, Q per
phase, S total, S per phase
0.05 x Ib... Imax 1
Active energy EaIn, EaOut, Ea Abs, Ea, EaIn
EaOut
0.05 x Ib... Imax 1
Reactive energy ErIN, ErOut, Er Abs, Er 0.05 x Ib... Imax 2
Apparent energy Es 0.05 x Ib... Imax 1
Average power over interval P Dmd per phase, P Dmd Total, Q
Dmd per phase, Q Dmd Total, S
Dmd per phase, S Dmd Total
0.05 x Ib... Imax 1
Max P Dmd per phase, Max
P Dmd Total, Max Q Dmd per
phase, Max Q Dmd Total, Max S
Dmd per phase, Max S Dmd Total
Average currents over
interval
I1 Dmd, I2 Dmd, I3 Dmd, IN Dmd,
Iavg Dmd, Max I1 Dmd, Max I2
Dmd, Max I3 Dmd; Max IN Dmd,
Max I1 Dmd, Max I2 Dmd, Max I3
Dmd; Max IN Dmd
0.2 x Ib ... Imax 0.5
Power factors PF1, PF2, PF3, PFtot, Cos 1,
Cos 2, Cos 3, Cos tot
0.5 inductive to
0.8 capacitive
1
Voltage THD THDU (ph.-ph.), THDV (ph.-N) 0…20% 2
Current THD THDI per phase or per neutral
pole
0…200% 2