Electro Industries/GaugeTech Nexus 1250, Installation & Operation Manual

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Voltages between the phases vary depending on loading factors and the quality of distribution
transformers. The three phase system is distributed in different voltage levels: 208VAC; 480VAC;
2,400VAC; 4,160VAC; 6,900VAC; 13,800VAC, etc.
1.3: Poly Phase Power Systems 1.3: Poly Phase Power Systems
Power measurement in a poly phase system is governed by Blondel’s Theorem. Blondel’s Theorem
states that in a power distribution network that has N conductors, the number of measurement elements
required to determine power is N-1. A typical configuration of a poly phase system has either a Delta
connection or a Wye connection.
e
Electro Industries/GaugeTech
Doc #: E107-7-06-121
1-3
1.4: Consumption, Demand and Poor Power Factor 1.4: Consumption, Demand and Poor Power Factor
n
Consumption is the total electric energy usage over a time period, expressed in WH.
W = instantaneous power; T = time in hours.
WH = W x T
Consumption is typically measured in kilowatt-hours (kWh): one thousand watts consumed over one
hour. Utilities use the WH equation to determine the overall consumption in a billing period.
Delta
Wye
Figure 1.4: Poly Phase Power Systems
Courtesy of NationalSwitchgear.com