Auto-recovery overcurrent protection for audio notification appliance circuit in fire protection system

A method of operating an audio system, comprising:

• configuring a notification appliance circuit (NAC) having one or more speakers to reproduce sound;
• configuring an amplifier circuit to drive the one or more speakers;
• configuring a relay circuit to selectively connect or disconnect the speakers to or from the amplifier circuit responsive to an enable amplifier control signal or a disable amplifier control signal, respectively;
• configuring a logic element to generate the enable amplifier control signal or the disable amplifier control signal responsive to an absence or a presence of an overcurrent condition in an output of the amplifier circuit, respectively;
• configuring an overcurrent detection circuit to detect the absence or the presence of the overcurrent condition;
• configuring a current sensor to receive a first alternating current (AC) signal output from the amplifier circuit and generate a second AC signal that simulates the first AC signal;
• configuring a rectifier to convert the second AC signal into a direct current (DC) signal;
• configuring an amplifier to amplify the DC signal into an amplified DC signal;
• and
• configuring a comparator to generate a MUTE signal to mute the amplifier circuit responsive to the amplified DC signal during at least a portion of the overcurrent condition to prevent arcing of contacts of the relay circuit.

A method of operating an audio system, comprising:

• selectively driving, by an amplifier circuit, one or more speakers of a notification appliance circuit (NAC);
• selectively connecting or disconnecting, by a relay circuit, the amplifier circuit from or to the one or more speakers responsive to an enable amplifier control signal or a disable amplifier control signal, respectively;
• detecting, by an overcurrent detection circuit, an absence or a presence of an overcurrent condition in an output of the amplifier circuit;
• generating, by a logic element, the enable amplifier control signal or the disable amplifier control signal responsive to the absence or the presence of the overcurrent condition in the output of the amplifier circuit, respectively-;
• generating, by a current sensor, a second AC signal that simulates a first AC signal output from the amplifier circuit;
• converting, by a rectifier, the second AC signal into a direct current (DC) signal;
• amplifying, by an amplifier, the DC signal into an amplified DC signal;
• and
• generating, by a comparator, a MUTE signal to mute the amplifier circuit responsive to the amplified DC signal during at least a portion of the overcurrent condition to prevent arcing of contacts of the relay circuit.