Metering and billing has historically been defined for the fundamental quantities. In the past, both the supply voltages and loads were predominantly linear, which, coupled with the capability limitations of electromechanical meters, made fundamentalenergy measurement the best option. However, with the advent and phenomenal growth of non-linear loads (as LED lamps, SMPS etc.) and micro-generation, harmonics were introduced in the power system, and so energy suppliers are preferring to use the totalenergy for billing purpose based on its physical significance of real workable energy delivered. Though the concept of total active power is unambiguous, there is no unique definition of reactive power and apparent power for non-sinusoidal conditions. The matter is further complicated for computing apparent power / energy for polyphase systems. Different meter manufacturers use different computational methods for these energies, culminating in different values for billing parameters like power factor, kVA demand and kVAh energy for the same quantity and quality ofpower supplied.
展开▼
