The Edco SRA16C-1 is a three terminal device, two of which are connected across the signal inputs of the detector for differential mode protection, and the third is grounded to protect against common mode damage.
Differential mode surges (induced voltage across the loop detector input terminals) are clamped by a semiconductor array instantly. The array is designed to appear as very low capacitance to the detector.
Common mode surges (induced voltage between the loop leads & ground) are handled by a rugged three-element gas discharge tube which operates (fi res) at 90 VDC and thereafter clamps the two loop leads to 30 volts in respect to ground. This design eliminates any ground noise from entering the loop detector and being amplifi ed. The Edco SRA16C-1 is intended for all current detector models on the market.