T.I. Chen Blog

  • 2019-05-21May

    AC Current Transformer Burden

    The AC current transformers used for the accurate measurement of AC electric currents are designed to transform the AC primary current to a proportional AC voltage signal or a lower proportional AC current signal level that is appropriate for micro-processor based systems. The VA burden that is imposed on the AC current transformer secondary signal […]


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  • 2019-04-16April

    Accuracy Class for Current Transformers

    The accuracy performance of an AC current transformer’s primary current to secondary signal transformation (where the secondary is either a current or voltage) is stated as Accuracy Class. The Accuracy Class for current transformers is measured in accordance with the IEC61869 standard. The IEC61869-2 standard specifies transformation accuracy for current transformers at different percentage levels […]


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  • 2019-04-16April

    DC Current Measurement

    The non-intrusive measurement of a DC current is accomplished through the use of electronic sensors that use the Hall Effect to monitor and measure electrical currents. Hall Effect sensors used for DC current measurement are configured with an opening for the primary conductor. Matching the opening size to the outside diameter of the primary conductor […]


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  • 2019-02-07February

    AC Voltage Measurement, Intelligent Devices

    The accurate measurement of AC Voltage is complicated by the necessity to minimize the burden the measuring instrument places on the primary circuit. The incorporation of a 1:1 current style voltage transformer in the AC voltage measuring circuit offers several advantages. Features A minimal burden on the primary voltage circuit, with essentially zero primary circuit […]


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  • 2019-01-14January

    AC Current Measurement, Intelligent Devices

    The Supervisory Control and Data Acquisition (SCADA) systems used by electric utilities to manage the distribution of electric power are highly dependent upon the intelligent, micro-processor based devices installed throughout the electric power distribution grid. These intelligent devices acquire in real time the critical performance measurements (e.g. current, voltage), transmitting that information back to the […]


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  • 2018-12-03December

    AC Electric Power Monitoring and Measurement Sensors

    Retrofitting Existing Distribution Networks The current generation of electric power AC current sensors that are suitable for retrofitting existing distribution networks have obtained a level of accuracy capable of near revenue grade metering. These split-core sensor designs permit the installation of the AC current sensor without taking the primary conductor off-line. The standard solid-core AC […]


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  • 2018-09-17September

    Micro-Grid, Option for Restoring Electric Power to Puerto Rico

    I have read several interesting stories of organizations proposing and installing Micro-Grids as a means of restoring electric power to areas in Puerto Rico. The Micro-Grid systems incorporate electric power generation, electric power storage and/ or smart-grid connection to the electric utility distribution network. The installations goals are; Restoring electric power. Providing backup to critical […]


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  • 2016-09-23September

    California Zero Net Energy Program: Part 2

    The California Zero Net Energy program discussed in the previous post will have a significant impact on new construction. The average residential electric power usage in the State of California is 6,741 kWh per year (U.S. Energy Information Administration) or 18.5 kWh per day on average. Presumably a residential home will generate electric power using […]


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  • 2016-09-16September

    California Zero Net Energy Program

    I recently read an article about the California Zero Net Energy program whose stated goal is that all new residential construction in California will be zero net energy by 2020. All new commercial construction will be zero net energy by 2030. Zero Net Energy (ZNE) is defined to be that the building will produce as […]


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  • 2015-11-13November

    Free Electric Power

    The New York Times published an article recently on how TXU Energy (Dallas/ Fort Worth, Texas) is offering their customers free electricity during certain times of the day. A little background may be helpful. There are three electrical grids that cover the mainland United States, essentially East coast, West coast and Texas. Several years ago, […]


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