Detection of Floating Neutral Condition in a Form 2S Electric Meter

Abstract

In North American, most residential electrical meters are of the form 2S type. While the neutral conductor from the split-phase transformer to the customer’s service panel is routed through the meter socket, the meter does not have a connection to the neutral conductor. Line 1 and line 2 voltage magnitudes are nominally equal when referenced to the neutral. Conditions arise that the neutral connection becomes compromised, in which case the line 1 and line 2 voltages become unbalance, creating potentially hazardous conditions. This paper describe an algorithm in a form 2S smart meter can use to detect a faulted neutral connection by observing changes in the currents seen by the meter even though it does not have a direct connection to the neutral reference point. Results of laboratory experiments show that it is possible to detect faulted neutral conditions in a typical household in less than a day.