D

decibel (dB): The standard unit that expresses relative power of signal levels in terms of the ratio of the logarithm of the power output to power input; i.e., decibel (dB) 10 log ₁₀ ( P ₁/ P ₂) for power.
delta: A standard three-phase circuit connection configured such that the ends of each phase winding connected in series form a closed loop with each phase 120 electrical degrees from the other. It appears as a triangle and looks like the Greek letter delta ( ?).
delta connection: A method of connecting a three-phase source or load in series to provide a closed circuit (three-wire, plus ground).
delta-delta: Three-phase transformer circuit created by a delta source and a delta load with both the primary and secondary windings connected in a delta configuration.
delta-wye: Three-phase transformer circuit created by a delta source and a wye load with the transformer primary connected in a delta configuration and the transformer secondary connected in a wye configuration.
demand (kW): The total amount of electrical power at any given time that a utility customer requires from the utility.
demand billing: Billing based on the electrical demand, as specified in the rate schedule or contract, that a customer requires from the utility.
demand charge: The specified charge or rate that the utility charges its customers to pay for the amount of maximum power they use in a specified time period, usually a month.
derating factor: A factor in percent for reducing...

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Power Quality Primer

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