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
Slide 8
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
Slide 9
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
Slide 10
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