2–4 EPM 6000 MULTI-FUNCTION POWER METERING SYSTEM – USER GUIDE
CHAPTER 2: ELECTRICAL BACKGROUND
2.2.3 Delta Connection
Delta connected services may be fed with either three wires or four wires. In a three-phase
delta service the load windings are connected from phase-to-phase rather than from
phase-to-ground. The following figure shows the physical load connections for a delta
service.
FIGURE 2–3: Three-Phase Delta Winding Relationship
In this example of a delta service, three wires will transmit the power to the load. In a true
delta service, the phase-to-ground voltage will usually not be balanced because the
ground is not at the center of the delta.
The following diagram shows the phasor relationships between voltage and current on a
three-phase delta circuit.
In many delta services, one corner of the delta is grounded. This means the phase to
ground voltage will be zero for one phase and will be full phase-to-phase voltage for the
other two phases. This is done for protective purposes.
FIGURE 2–4: Three-Phase Voltage and Current Phasors for Delta Winding
Ia
Ica
Iab
Ib
Ibc
Ic
Vab
Vbc
A
B
C
Vca
Vbc
Vca
Vab
Ic
Ib
Ia
To Next Page
Loading...
