App-1
IM WT310E-01EN
Appendix
1
2
3
4
5
6
7
8
App
Index
Appendix 1 Symbols and Determination of
Measurement Functions
Measurement Functions Used in Normal Measurement
Upk
Urms
Ipk
Irms
P
S
cos
–1
( )
P
S
Select from Urms • Irms, Umn • Irms, and Udc • Idc.
AVG[u(n)
•
i(n)
]
AVG[u(n)
2
]
AVG[i(n)
2
]
Voltage crest factor CfU =
Current crest factor CfI =
Voltage crest factor: CfU
Current crest factor: CfI
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]
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
Upk= |U+pk| or |U-pk|,
whichever is larger
Ipk = |I+pk| or |I-pk|,
whichever is larger
Active power P [W]
Reactive power Q [var]
Apparent power S [VA]
Power factor λ
Phase difference Φ [°]
Measurement Function
Voltage
U [V]
Current
I [A]
The phase angle displays lead (D) and lag (G).
Methods of Computation and Determination
For information about the symbols in the equations,
see the notes on the next page.
Voltage frequency: fU (FreqU) [Hz]
Current frequency: fI (FreqI) [Hz]
(Continued on next page)
(Table 1/2)
π
2
2
AVG[ u(n) ]
AVG[u(n)]
AVG[i(n)]
The voltage frequency (fU) and current frequency (fI) are measured
by detecting the zero-crossing points.
Measures fU and fI for the element set in display D of the WT
S
2
– P
2
s
•
s is -1 for a lead phase and 1 for a lag phase
Urms
Umn
Udc
Irms
Idc
True rms value
Urms
Rectified mean value calibrated
to the rms value
Umn
Simple average
Udc
True rms value
Irms
Simple average
Idc
Appendix
