YOKOGAWA WT500 User Manual page 170

5.17 Setting Delta Computation (Optional)
5-44
• Star>Delta
Using the data from a three-phase, four-wire system, the data of a delta connection is
computed from the data of a star connection (star-delta transformation).
ΔF1rms[Urs], ΔF1mn[Urs], ΔF1dc[Urs], ΔF1rmn[Urs], ΔF1ac[Urs]
ΔF2rms[Ust], ΔF2mn[Ust], ΔF2dc[Ust], ΔF2rmn[Ust], ΔF2ac[Ust]
ΔF3rms[Utr], ΔF3mn[Utr], ΔF3dc[Utr], ΔF3rmn[Utr], ΔF3ac[Utr]
ΔF4rms[In], ΔF4mn[In], ΔF4dc[In], ΔF4rmn[In], ΔF4ac[In]
* rms, mn, dc, rmn, and ac are delta computation modes.
R I
Urs
Utr
N
S
T
Ust
I
• Delta>Star
Using the data from a three-phase, three-wire system that uses a three-voltage, three-
current method, the data of a star connection is computed from the data of a delta
connection (delta-star transformation). The center of the star connection is computed
as the center of the delta connection. If the actual center of the star connection does
not match the center of the delta connection, an error results.
ΔF1rms[Ur], ΔF1mn[Ur], ΔF1dc[Ur], ΔF1rmn[Ur], ΔF1ac[Ur]
ΔF2rms[Us], ΔF2mn[Us], ΔF2dc[Us], ΔF2rmn[Us], ΔF2ac[Us]
ΔF3rms[Ut], ΔF3mn[Ut], ΔF3dc[Ut], ΔF3rmn[Ut], ΔF3ac[Ut]
ΔF4rms[In], ΔF4mn[In], ΔF4dc[In], ΔF4rmn[In], ΔF4ac[In]
* rms, mn, dc, rmn, and ac are delta computation modes.
I
R
Ur
In
Ut
Us
N
S
T
I
I
Selecting a Delta Computation Mode
You can select the voltage or current mode to be displayed as delta computation values
from the following:
rms, mean, dc, r-mean, ac
Note
• We recommend that you set the measurement range and scaling (VT/CT ratio and
coefficients) of the elements that are undergoing delta computation as closely as possible.
Using different measurement ranges or scaling causes the measurement resolutions of the
sampled data to be different. This results in errors.
• The numbers (1, 2, 3, and 4) that are attached to delta computation measurement function
symbols have no relation to the element numbers. The computation of delta measurement
functions Δ F1 to Δ F4 varies depending on the wiring system and the delta computation
type. For details, see appendix 10.
• On models with a single element, this function does not work. Therefore, the setup menus
do not appear.
• If the target wiring system for delta computation is a single-phase, two-wire system (1P2W),
delta computation cannot be performed.
±
I1
U
U1
±
In
± ±
U3 U2
U
U
I2
±
I3
±
I
±
I1
U U
U3 U1
± ±
I2
U
±
U2
±
I3
±
IM 760201-01E