GE EPM 6000 instruction manual Delta Connection, Three-Phase Delta Winding Relationship

CHAPTER 2: ELECTRICAL BACKGROUND

2.2.3Delta 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.

Vca

A

Vab

B

Vbc

C

Ia

Iab

Ib

Ibc

Ic

Ica

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.

Vca

Ic

Vbc

Ia

Ib

Vab

FIGURE 2–4: Three-Phase Voltage and Current Phasors for Delta Winding

2–4 EPM 6000 MULTI-FUNCTION POWER METERING SYSTEM – USER GUIDE