2-6
IM WT1801-01EN
Delta Computation (
Δ Measure; option)
The sum or difference of the instantaneous voltage or current values (sampled data) between the elements in
a wiring unit can be used to determine various types of data such as the differential voltage and phase voltage.
This operation is called delta computation.
Types of Delta Computation (
ΔMeasure Type)
The following types of delta computation are available:
• Differential voltage and differential current (Difference)
• Line voltage and phase current (3P3W > 3V3A)
• Star-delta transformation (Star>Delta)
• Delta-star transformation (Delta>Star)
The delta computation types that you can select vary as indicated below according to the wiring system.
Wiring System
Delta Computation Type
1P3W
Difference, 3P3W>3V3A
3P3W
Difference, 3P3W>3V3A
3P4W
Star>Delta
3P3W(3V3A)
Delta>Star
• Differential Voltage and Differential Current (Difference)
The differential voltage and differential current between two elements can be computed on a single-phase,
three-wire system or on a three-phase, three-wire system.
When you perform delta computation on wiring unit ΣA, the available measurement functions are as follows.
ΔU1rms[UdiffA], ΔU1mn[UdiffA], ΔU1dc[UdiffA], ΔU1rmn[UdiffA], ΔU1ac[UdiffA]
ΔIrms[IdiffA], ΔImn[IdiffA], ΔIdc[IdiffA], ΔIrmn[IdiffA], ΔIac[IdiffA]
* In the measurement functions,
rms
,
mn(mean)
,
dc
,
rmn(r-mean)
, and
ac
are the delta computation modes.
A
indicates the wiring unit.
• Line Voltage and Phase Current (3P3W > 3V3A)
You can compute unmeasured line voltages and phase currents by converting the data of a three-phase,
three-wire system to the data of the three-voltage, three-current method (3V3A).
T
R
S
T
R
S
When you perform delta computation on wiring unit ΣA, the available measurement functions are as follows.
ΔU1rms[UrsA], ΔU1mn[UrsA], ΔU1dc[UrsA], ΔU1rmn[UrsA], ΔU1ac[UrsA]
ΔIrms[ItA], ΔImn[ItA], ΔIdc[ItA], ΔIrmn[ItA], ΔIac[ItA]
±
±
±
±
I
R
S
T
U
U
I
N
I1
I2
U2
U1
Urs
It
* In the measurement functions,
rms
,
mn(mean)
,
dc
,
rmn(r-mean)
, and
ac
are the delta computation modes.
A
indicates the wiring unit.
2 Fundamental Measurement Conditions