Electric circuit and sensor for detecting arcing and a transparency having the circuit and sensor

An aircraft comprising a windshield, comprising a heatable member for removing snow, fog or ice from an outer surface of the windshield, the heatable member comprising a pair of spaced bus bars and an electrically conductive member between and in electrical contact with the spaced bus bars, and an electrical system to monitor and/or control performance of the heatable member, the electrical system comprising:

• a temperature sensor for sensing the temperature of the electrically conductive member;
• a first switch to be electrically connected to a power source of the aircraft;
• an arc sensor for monitoring voltage of the electrically conductive member, the arc sensor electrically connected to the first switch, wherein the first switch in a closed position provides a continuous electrical path from the power source of the aircraft through the first switch to the arc sensor and from the arc sensor to a first one of the pair of spaced bus bars of the heatable member, and the second one of the spaced bus bars of the heatable member connected to the power source, and the first switch in the open position prevents current from moving from the power source to the first bus bar;
• a temperature controller acting on the first switch to selectively open the first switch;
• a second switch electrically connecting the temperature sensor to the temperature controller, wherein the first switch in a closed position electrically interconnects the temperature sensor and the temperature controller, and in an open position disconnects the first switch and the temperature sensor;
• a filter and modifying system connected to the arc sensor and acting on the second switch,
• wherein with the first switch and the second switch in the closed position a first electric path is provided from the power supply through the first switch, through the heatable member to the power source, and a second electrically conductive path is provided from the temperature sensor, through the second switch, to the temperature controller,
• wherein the temperature controller opens the first switch when the temperature controller receives a predetermined signal from the temperature sensor, and
• wherein the filter and modifying system opens the second switch when a signal from the arc sensor indicates a predetermined level of arcing, and the temperature controller responsive to the opening of the second switch opens the first switch, if the first switch is closed.