Power measurement in a two-wire load control device

A two-wire lighting control device for controlling an amount of power delivered from an alternating current (AC) power source to a lighting load, the load control device comprising:

• a controllably conductive device configured to be coupled in series electrical connection between the AC power source and the lighting load;
• and
• a control circuit configured to:
• control the amount of power delivered to the lighting load by rendering the controllably conductive device non-conductive during a first portion of a half-cycle of an AC waveform and rendering the controllably conductive device conductive during a second portion of the half-cycle;
• measure a voltage across the two-wire lighting control device during the first portion of the half-cycle;
• compute an estimated voltage across the load during a second portion of the half-cycle based on the voltage measured across the two-wire lighting control device during the first portion of the half-cycle;
• measure a current supplied to the lighting load during the second portion of the half-cycle;
• and
• compute, based on the estimated voltage and the measured current, an estimated power consumed by the lighting load during the second portion of the half-cycle.

A method for estimating power consumption of a lighting load using a two-wire lighting control device, the two-wire lighting control device configured to control an amount of power delivered from an alternating current (AC) power source to the lighting load, the lighting control device having a controllably conductive device that is configured to operate in a non-conductive state during a first portion of a half-cycle of an AC waveform and in a conductive state during a second portion of the half-cycle, the method comprising:

• measuring a voltage across the two-wire lighting control device during a first portion of the half-cycle;
• computing an estimated voltage across the lighting load during a second portion of the half-cycle based on the voltage measured across the two-wire lighting control device during the first portion of the half-cycle;
• measuring a current supplied to the lighting load during the second portion of the half-cycle;
• and
• computing, based on the estimated voltage and the measured current, an estimated power consumed by the lighting load during the second portion of the half-cycle.