YOKOGAWA WT3002E - Page 101

6-4
IM WT3001E-51EN
• Star>Delta
Computes various data of a delta connection from the data of a star connection (star-
delta transformation) using the data from a three-phase, four-wire system.
 ∆F1[UrsA]
 ∆F2[UstA]
 ∆F3[UtrA]
 ∆F4[InA]
I
I
R
S
T
U
U
U
I
N
I1
I2
I3
U1
U2U3
UrsA
UtrA
UstA
InA
• Delta>Star
Computes various data of a star connection from the data of a delta connection (delta-
star transformation) using the data from a three-voltage, three-current system. The
neutral point of the star connection is computed as a centroid of the delta connection.
If the actual neutral point does not match the centroid, an error results.
 ∆F1[UrA]
 ∆F2[UsA]
 ∆F3[UtA]
 ∆F4[InA]
I
I
R
S
T
UU
U
I
N
I1
I2
I3
U3
U2
U1
UrA
UtA
UsA
InA
Note
• It is recommended that the measurement range and scaling (VT/CT ratio and
coefficients) of the elements that are being computed (delta computation) be set
the same as much as possible. Using a different measurement range or scaling
causes the measurement resolution of the sampled data to be different. In effect,
the computation result will have errors.
• The number (1, 2, 3, and 4) that is attached to the measurement function symbol of
the delta computation has no relation to the element number. The computation of
themeasurementfunctions∆F1to∆F4ofdeltacomputationvariesdependingon
the wiring system and the delta computation type. For details, see section 6.3.
• 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.
6.2 Setting the Delta Computation