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Output Transformer NRS 90227
figure 6 printed board assembly 81338 showing the input transformer
NRS 90208 and the output transformer NRS 90 227
Input Transformer NRS 90208
Output Transformer 90 227
figure 7 printed board assembly 81339 showing the input transformer NRS 90208
and the output transformer NRS 90 227
8.5 NRS 90224 pilot tone & ground fault surveillance
The extension NRS 90224 is meant for insertion. It includes a 19 kHz tone generator and a selective 19 kHz receiver
with evaluation stage for pilot tone surveillance. Also incorporated is a monitoring circuit with fault storage and display
driver, to guard the cable network connected to the output.
8.5.1 Pilot tone surveillance:
Integration of the extension NRS 90224 provides continuous self-monitoring of the amplifier. This gets accomplished in
the way that an extremely low-level 19 kHz pilot tone signal is introduced to the signal path following the input level
control LEVEL. After passing the amplifier stages, the pilot tone signal is filtered out at the output and the result is
evaluated. If the measured signal declines the pilot tone's predetermined threshold at the output or is not present at
all, the READY indicator (7) dims and the READY fault message relay drops. When using the INPUT MODULE NRS
90225, the fault message is output as collective fault message with the floating contact of the READY fault message
relay via the REMOTE CONTROL connector (16). When using the REMOTE MODULE NRS 90222, error occurrence
is monitored and output by the PROMATRIX manager DPM 4000 (for further details, please refer to the PROMATRIX
handbook).
8.5.2 Ground fault surveillance:
When installing and operating 100V-loudspeaker networks, compliance to the VDE regulation DIN VDE 0800 is
mandatory. Especially, if 100V-loudspeaker networks are included in alarm system applications, all security
standards have to be in accordance to the security class 3 standard.