The 1S30 is an optical sensor that responds to the flash of light emitted during the incidence of an arcing fault. Onset of the light flash & detection by the 1S30 occurs in a few ms.
Each arc fault sensor consists of one or two silicon PIN photodiode light detectors mounted on a circuit board together with an associated detection circuit. The detector monitors a wide space angle. and provides a A broad spectral response in the visible region.
Sensitivity of the arc sensor has been set to a low level to reduce the possibility of maloperation under high ambient lighting conditions. This is made possible due the high intensity of light emitted under arc fault conditions. Additional security can be incorporated by way of a current check stage as described in the 1S20 Arc Fault Monitor Technical Bulletin.
In stand by mode the 1S30 sensor presents a high resistance to the 12V DC control signal provided by the 1S20, or 1S25 Arc Fault Monitors. This allows a small circulating current to flow for continuous supervision of the 1S30 connection circuit. When an arc is detected, the resistance presented by the 1S30 drops to a level where the current flow increases to approximately 20mA. This increased current flow is instantaneously detected by the Arc Fault Monitor & its trip output contacts closed. Refer to the 1S20 Arc Fault Monitor Technical Bulletin for further details.