1-5
IM 253710-01E
Functions
1
1.2
Measurement Modes and Measurement/
Computation Periods
There are two measurement modes, normal measurement and harmonic measurement.
Normal Measurement Mode and Measurement Function (Types of Numerical Data)
«For procedures, see section 5.1.»
The data specified by the measurement function (numerical data) in the normal
measurement mode are measured or computed over the specified period of the sampled
data* as described later in “Measurement/Computation Period.”
*
For information on the sampled data, see section 1.3 “Acquiring Data (Voltage and Current
Signals).”
Measurement function (types of numerical data)
• Measurement function on each power measurement module
The following 29 types of numerical data can be determined. For details related to
the determination of measurement function data, see “Appendix 2.”
U (voltage Urms, Umn, Udc, Uac), I (current Irms, Imn, Idc, Iac), P (active power),
S (apparent power), Q (reactive power),
λ
(power factor),
φ
(phase difference), fU/fI
(frequency of voltage/current), U+pk/U-pk (maximum/minimum values of voltage),
I+pk/I-pk(maximum/minimum values of current), CfU/CfI(crest factor of voltage/
current), FfU/FfI (form factor of voltage/current), Z (impedance of the load circuit),
Rs/Xs (resistance/reactance of the load circuit that has a resistor R, inductor L, and
capacitor C connected in series), Rp/Xp (resistance/reactance of the load circuit
that has a R, L, and C connected in parallel), Pc (Corrected Power)
• Measurement function of the average or sum of multiple measurement
modules (
Σ
function)
The following 19 types of numerical data can be determined. For details related to
the determination of measurement function data, see “Appendix 2.”
U
Σ
(voltage average Urms
Σ
, Umn
Σ
, Udc
Σ
, Uac
Σ
), I
Σ
(current average Irms
Σ
, Imn
Σ
,
Idc
Σ
, Iac
Σ
), P
Σ
(sum of active powers), S
Σ
(sum of apparent powers), Q
Σ
(sum of
reactive powers),
λΣ
(power factor average),
φΣ
(phase difference average), Z
Σ
(impedance average of the load circuit), Rs
Σ
/Xs
Σ
(average of the resistance/
reactance of the load circuit that has a R, L, and C connected in series), Rp
Σ
/Xp
Σ
(average of the resistance/reactance of the load circuit that has a R, L, and C
connected in parallel), Pc
Σ
(sum of Corrected Powers)
• Efficiency (
Σ
function)
η
(Efficiency 1), 1/
η
(Efficiency 2). See “Efficiency” on the next page.
• Measurement function of the motor module
The following seven types of numerical data can be determined. For details related
to the determination of measurement function data, see “Chapter 15.”
Speed (rotating speed), Torque, Sync (synchronous speed), Slip, Pm (motor output
or mechanical power), motor efficiency (
η
mA or
η
mB), total efficiency (
η
mA or
η
mB).
Determining the voltage and current
There are four types of measurement functions for voltage (U) and current (I).
• Urms, Irms (true rms value)
These values are the true rms values of the voltage and current. The
instantaneous values over one period are squared and averaged. Then, the rms
value is determined. Let f(t) represent the input signal as a function of time and let
T be the period of the signal.
Urms or Irms =
1
T
0
T
f(t)
2
dt
