Appendix; Appendix 1 Symbols And Determination Of Measurement Functions - YOKOGAWA WT1800 User Manual

Appendix

Appendix 1 Symbols and Determination of
Measurement Functions Used in Normal Measurement
Measurement Function
True rms value: Urms
Rectified mean value
Voltage
calibrated to the rms value: Umn
U [V]
Simple average: Udc
Rectified mean value: Urmn
AC component: Uac
True rms value: Irms
Rectified mean value
Current
calibrated to the rms value: Imn
I [A]
Simple average: Idc
Rectified mean value: Irmn
AC component: Iac
Active power P [W]
Apparent power S [VA] TYPE1,
TYPE2
TYPE3
Reactive power Q [var] TYPE1,
TYPE2
TYPE3
Power factor λ
Phase difference Φ [˚]
Voltage frequency: fU (FreqU) [Hz]
Current frequency: fI (FreqI) [Hz]
Maximum voltage: U + pk [V]
Minimum voltage: U – pk [V]
Maximum current: I + pk [A]
Minimum current: I - pk [A]
Maximum power: P + pk [W]
Minimum power: P – pk [W]
Voltage crest factor: CfU
Current crest factor: CfI
Corrected Power Pc [W]
IM WT1801-03EN
Measurement Functions
Methods of Computation and Determination
For information about the symbols in the equations,
see the notes at the end of page App-3.
Urms Umn
π
AVG[ u(n) ]
2
AVG[u(n) ]
2
2
Irms Imn
π
AVG[ i(n) ]
2
AVG[i(n) ]
2 2
Select from Urms • Irms, Umn • Imn, Udc • Idc, Umn • Irms, and Urmn • Irmn.
s is -1 for a lead phase and 1 for a lag phase
Q(k) = Ur(k) • Ij(k) –Uj(k) • Ir(k)
Ur(k) and Ir(k) are the real number components of U(k) and I(k)
Uj(k) and Ij(k) are the imaginary components of U(k) and I(k)
Valid only when harmonics are being measured correctly.
The phase angle can be switched between lead (D)/lag (G) display and 360˚ display.
The voltage frequency (fU) and current frequency (fI) are measured by detecting
the zero-crossing points.
You can simultaneously measure three frequencies from the frequencies fU and fI
of all the installed elements.
On models with the add-on frequency measurement option, the fU and fI of all
elements can be measured simultaneously.
The maximum u(n) for every data update
The minimum u(n) for every data update
The maximum i(n) for every data update
The minimum i(n) for every data update
The maximum u(n) • i(n) for every data update
The minimum u(n) • i(n) for every data update
Voltage crest factor CfU =
Upk = |U + pk| or |U – pk|
whichever is larger
IEC76-1(1976), IEEE C57.12.90-1993
P
(
Urms
P1 + P2
Umn
P1, P2: coefficients defined in the
applicable standards
Udc
AVG[u(n)] AVG[ u(n) ]
Idc
AVG[ i(n) ]
AVG[i(n)]
AVG[u(n) i(n) ]
•
2 2
P + Q
2 2
s S – P
•
max
Q(k)
k = min
P
S
( )
P
–1
cos
S
Upk
Current crest factor CfI =
Urms
Ipk = |I + pk| or |I – pk|
whichever is larger
IEC76-1(1993)
(
)
2
P 1 +
(Table 1/3)
Urmn Uac
2 2
RMS -DC
Irmn Iac
2 2
RMS -DC
Ipk
Irms
)
Umn – Urms
Umn
(Continued on next page)
App-1
1
2
3
4
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App
Index