Speaker Line Current Sensor and Ground Fault Indicator

The Model 596SGFI is a dual channel, current sensing / ground fault detector module. In conjunction with the GCK Monitor / Test system, it can be used to monitor the current being drawn from the amplifier by a speaker circuit. When connected to a floating amplifier output it can detect a ground fault on a speaker line.

The 596SGFI is a current to voltage conversion device that is wired in series with the loudspeakers connected to a power amplifier output. The audio monitor output terminals are normally connected to the audio input of a 1544ZOP or the monitoring input of an AtlasIED monitor device. The voltage available at the output terminals is a function of the current delivered to the speakers.

Once the test signal level and the amplifier gain are set, the amplifier output voltage remains constant during normal testing conditions unless a fault occurs in the amplifier. The speaker line impedance varies due to changes in environmental conditions such as humidity and temperature, or due to a change in equivalent speaker circuit impedance because of speakers opening or shorting.

To detect ground faults, the 596SGFI requires external +5 VDC power. No power is required to measure speaker load current. The 596SGFI can be mounted in a SNAPTRACK (part # 3TK2-48) which is available at TE Connectivity (www.tti.com). The modules can be ‘daisy-chained’ together, requiring power to be run to the first module in the chain only, thereby simplifying the installation.