SBIR-STTR Award

Power measurement and power control are major energy management and energy conservation growth industries. Newly patented current-to-voltage transducer (CVT) technology is smaller,safer, and less expensive than current transformers (CTs). Inaddition, this noncontact CVT monitors current in multiconductorcables noninvasively @s cannot. Research is needed to expand theunderstanding ease of application, and accuracy of these CVTS. InPhase I a theoretical behavior model of magnetic fieldsaround multiple, current g conductors will be developed,especially as it pertains to wire gauge, conductor spacing and wiretype. This model will be compared to and refined with test data. Experimental research will characterize the variables inmulticonductor cables of different wire gauges and types fromdifferent manufacturers. Phase I will focus on currentmeasurements with NM 14-8 gauge cables. These data will beanalyzed to produce equations that predict signal output for thesensor for each wire type and gauge. Each gauge will havedifferent "k" coefficients. @ wire VM and wire gauge data becomethe only inputs a user needs to give to a microprocessor in thefield; these inputs are readily available. Phase R will extend thework to SE 8-4(0) cable and expand understanding of thetechnology's multiconductor, noninvasive voltage measuringcapability.Anticipated Results/Potential Commercial Applications as described by the awardee:This effort is expected to reduce the technologyfor noninvasive monitoring of current, voltage, and power inmulticonductor cables to consistent practice. Opportunities togather new data will result. CVT sensors can be incorporated incircuit breakers and can replace CTs for demand metering, whileeliminating the needed test switch. Being safer and lower in cost,CVT sensors may also replace CTs monitoring current in singleconductors. A market already exists for CVT sensors with electricpower companies, commercial energy management equipmentmanufacturers, and vendors of the Smart Home concept.

Power measurement and control are major energy management and energy conservation growth industries. Patented current-to-voltage transducer (CVT) sensor technology is smaller, safer, and less expensive than conventional current transformer (CT) sensor technology. In addition, the CVT accurately monitors current in multiconductor nonmetallic (NM) cables non-invasively, while CTs cannot. Phase I resulted in defining the primary variables that constrain the accuracy of the sensor on Llat NM cable of gauges 14 to 8. It was determined that the sensor signal is dependent on load, conductor spacing, and gauge in varying degrees. The primary purpose of Phase I was to determine whether functions, by gauge, could be developed that were within +10% of measured current. Equations for sensor output to load were developed for each gauge with accuracy of +2.5% or better. A general equation for all four gauges (14, 12, 10, and 8) was within 10%, and within 5% for gauges 14, 12, and 10. In Phase II, these accuracies are expected to improve dramatically with sensor redesign efforts. A theoretical model based on the principle of superposition was confirmed experimentally. Proprietary technology was refined for use in determining the distance between conductors. This same technology is used to provide for the non-invasive measurement of phase angle for power factor calculations. Research in Phase II will (1) extend the understanding developed in Phase I from flat NM cable to round NM cable and to service entrance (SE) cable of 0-0000; (2) optimize sensor materials and geometry to produce greater signal linearity; (3) reduce the technique for measuring the distance between conductors to consistent practice; and (4) refine the sensor signals for power factor calculations. Development work in Phase II will (1) determine sensor manufacturing tolerances; (2) prototype a peak alert monitor; (3) prototype a 240 volt sensor for flat NM cable; and, (4) prototype an enhanced version of the sensor.Anticipated Results/Potential Commercial Applications as described by the awardee:The primary benefit expected is the development of a new class of current sensors (CVTs) capable of monitoring current in single and multiconductor cables. These sensors will be small, low in cost, and inherently safe. Commercial applications include (1) current and power factor sensors; (2) sensors and display systems that could be sold into the utility market for customer service and marketing tools; and (3) sensors for original equipment manufacturers for inclusion in appliances and in energy management and control systems.