Patent ID: 8373571

Claim:
A safety notification system comprising: a detector device configured to detect an alarm event and to generate an indication of the alarm event; a fire control panel connected to the detector device and configured to receive the indication from the detector device and to generate a notification signal based on the indication; and an arrangement connected to the fire control panel and configured to receive the notification signal, the arrangement comprising: an alarm signal power source, the alarm signal power source configured to generate bias power for activating a notification appliance circuit of a notification extension loop responsive to receiving the notification signal; at least a first semiconductor device having a load path coupled between the alarm signal power source and the notification appliance circuit to selectively activate the notification appliance circuit; a current sensing unit operably coupled between the alarm signal power source and the first semiconductor device and configured to generate a current sensing signal that is dependent on the current in the load path, the current sensing signal indicative of whether the current through the load path exceeds an in-rush current threshold; a processing circuit operably coupled to a current measurement circuit which is coupled to the current sensing unit and configured to generate an overcurrent detection signal, based on the current sensing signal, indicative of whether an average of the current through the load path over a predetermined period of time exceeds a steady state current threshold, the steady state current threshold being different from the in-rush current threshold; and a controller circuit operably connected to receive the current sensing signal and wherein the controller circuit is configured to control the first semiconductor device responsive to the current sensing signal exceeding the in-rush current threshold and the average of the current over the predetermined period of time being less than or equal to the steady state current threshold; wherein the processing circuit is configured to cause the controller circuit to control the first semiconductor device such that the first semiconductor device does not conduct the current through the load path responsive to the overcurrent detection signal, different from the current sensing signal, indicating that the average of the current through the load path over the predetermined period of time exceeds the steady state threshold.