Question: How should detectors SPD-3.2 with normally open contacts be connected by the 4-wire scheme so that a control panel would pass to the status “Refuse”, not to the status “Fire”?
Answer: At the present detectors SPD-3.2 are produced with the installment possibility inside a detector parallel to output contacts of a resistor relay, the rating of which is set when ordering the product. In this case the open-circuit of a loop would occur when removing a detector from a base, and a control panel fixes that as a fault. When a detector installed on its place activates the loop resistance will increase. The rating of a built-in resistor must conform to requirements of the operational documentation for a fire control panel in order to appraise correctly the resistance change by a control panel. That is it is required to indicate the one when detectors are ordered. This information is represented in the latest edition of SPD-3.2 passport.
