For either coil arrangement, the voltage and current produced by a single winding can be measured. Once the voltage or current of one "phase" (coil) of the alternator is determined, the "sum of the three phases" is computed by multiplying by the square root of 3.

Wye Arrangement:

volts of 1 phase *V3 = volts of three phases current of 1 phase = current of three phases

coil

Delta Arrangement:

current of 1 phase * V3 = current of three phases volts of 1 phase = volts of three phases And for both arrangements:

Itotal Icoil *

Etotal Ecoil total total total

Example 1: a single coil, turning at 600 RPM, generates 1 volt at 0.1 amp. Let's compute the total voltage, total current, and total power, for both Wye and Delta arrangements.

Solution:

Wye Arrangement:

Etotal = Ecoil * V3 = Ecoil * 1.732 = 1 * 1.732 = 1.732 volts Itotal = Icoil = 0.1 amp

Ptotal = Etotal * Itotal = 1.732 * 0.1 = 0.1732 watts

Delta Arrangement:

Itotal = Icoil * V3 = Icoil * 1.732 = 0.1 * 1.732 amps = 0.1732 amps

Ptotal = Etotal * Itotal = 1 * 0.1732 = 0.1732 watts

The Wye arrangement produces more voltage, 1.732 volts for the Wye versus 1.0 volts for the Delta. Conversely, the Delta produces more current, 0.1732 amps versus only 0.1 amp for the Wye arrangement.

However, the power output, 0.1732 watts, is exactly the same for both coil arrangements. This power output is called the "no load" output. A "load" is the electrical device to which electrical power is delivered. The load may be a light fixture, an electrical appliance, a battery, or something of this type. In the next section, we'll calculate the power output with a load.