초록 ▼

A conventional ground fault circuit interrupter (GFCI) is modified to provide frequency-selective current protection. A control element is connected in series with the line path (or return path) of the GFCI, and a bypass element is connected in parallel with the combination of the control element an

A conventional ground fault circuit interrupter (GFCI) is modified to provide frequency-selective current protection. A control element is connected in series with the line path (or return path) of the GFCI, and a bypass element is connected in parallel with the combination of the control element and the line path (or return path) of the GFCI. Under normal conditions, little or no current flows through the bypass element. However, frequency response characteristics of the control and/or bypass elements are such that a frequency-selective component of the current (i.e. high-pass, low-pass or band-pass) is diverted through the bypass element. When the magnitude of the frequency-selective component reaches a predetermined value, the bypass current flow causes sensing of a resulting current imbalance and tripping of the GFCI.

대표청구항 ▼

1. A frequency-selective circuit protection arrangement for connection to an electrical path including a phase line and a return line between an alternating frequency power source supplying power at a line frequency and a load, comprising:a ground fault circuit interrupt switch for interrupting the

1. A frequency-selective circuit protection arrangement for connection to an electrical path including a phase line and a return line between an alternating frequency power source supplying power at a line frequency and a load, comprising:a ground fault circuit interrupt switch for interrupting the electrical path in response to a trip current, a fault current detector transformer having a phase line winding connected in series with the phase line, a return line winding connected in series with the return line, and a current sense winding for detecting an imbalance in electrical currents at line frequency passing through the phase line and the return line and for generating and applying the trip current to operate the ground fault circuit interrupt switch, and a transformerless, frequency-selective bypass circuit for bypassing electrical currents at a selected frequency different than the line frequency around one of the phase line winding and the return line winding, whereby when a current at the selected frequency is present at or above a predetermined minimum level, the bypass circuit causes an imbalance in current to flow through the fault current detector transformer and to cause the current sense winding to generate the trip current.