Slide 1

Caroline Storm Sponsored by: Dr. David Wetz, Simon Donahue

Slide 2

Introduction to GFCIs

Slide 3

Introduction to Smart Meters

Slide 4

Introduction to GFCIs

Slide 5

The Problem Construction sites power lines are exposed to the weather, for safety they have GFCIs on the line The GFCIs are installed close to the Smart Meters Due to the proximity the GFCIs are tripping

Slide 6

Hypothesis The RF created magnetic field is causing the differential transformer to detect extra current on the hot side relative to the neutral side Where does the interference originate? Magnetic coupling on the hot line Magnetic coupling with the differential transformer RF transmission being picked by internal wiring in the smart meter Magnetic field effecting the solenoid

Slide 7

Discoveries thus far Two identical GFCIs, except the material used for the hot line When copper is used for the hot line, GFCI does not trip Covering the hot line in copper also keeps the GFCI from tripping

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Discoveries thus far Eatons studies found that placing ferrite beads on the lines between the GFCIs and the Meter solves the problem However, connecting the GFCIs to a separate power supply has no effect

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Inferences Direct interaction with differential transformer or RF transmission in the internal wiring are not the cause Most likely the faulty tripping is caused by magnetic coupling with the hot line or the hot conductor in the GFCI

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Further avenues to explore What is the strength of the magnetic field coming directly off the wire Does the placing of the ferrite bead affect the impact of the ferrite bead on the fault What is the threshold voltage of at which the differential transformers sends the trip signal

Slide 11

Questions?