Low cost self-contained transformerless solid state electronic watthour

Abstract

A transformerless, self-contained, low cost, small size, light weight solid state electronic watthour meter is described which employs thin film ferromagnetic current sensors of the type which are magnetically coupled to power conductors whose current flow is to be sensed and metered and which provides electrical isolation between the power conductors and the sensing and metering circuitry. The meter is self-contained in that it draws its operating direct current supply potential required to operate the meter directly from the power conductors being metered and does not require a separate battery or transformer coupled direct current power source. The entire meter circuitry, including the thin film ferromagnetic current sensors which can be fabricated by thin film technology and the direct current power supply and the watthour meter circuitry, all are susceptible of fabrication on a single substrate using semiconductor integrated circuit fabrication techniques.