Effects of smart meter RF on GFCI units

Caroline StormSponsored by: Dr. David Wetz, Simon

Donahue

Introduction to GFCIs

Introduction to Smart Meters

Introduction to GFCIs

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

HypothesisThe 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 lineMagnetic coupling with the differential transformerRF transmission being picked by internal wiring in

the smart meterMagnetic field effecting the solenoid

Discoveries thus farTwo 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

Discoveries thus farEaton’s 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

InferencesDirect 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

Further avenues to exploreWhat 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

Questions?