C
APPENDIX
5
INTELLIGENT ENVIRONMENTAL COMPENSATION (IEC)
Intelligent Environmental Compensation (IEC) is an optional feature that permits the
FireFinder-XLS system to compensate automatically for environmental changes (such
as dirt and dust buildup) in the analog voltage of an HFP-11 detector on a DLC loop or
an I-Series photo or ion detector on an MLC loop. The selection of IEC devices is
made in the Zeus programming tool.
For the FDOOTC441/OOHC941, FDOOT441/OOH941, FDOT421/OH921, FDT421/HI921,
and FDO421/OP921 detectors, the IEC must be enabled on the XLS node level.
Once a detector is chosen to be covered by IEC, FireFinder-XLS stores and analyzes
the analog readings of the smoke detector and adjusts the detector’s threshold
upward or downward, as necessary, to maintain a constant sensitivity.
As the analog voltage increases due to environmental factors, an equivalent increase
in the detector’s alarm threshold prevents factors other than smoke from causing an
alarm. This method maintains the selected detector’s sensitivity.
Typically, the analog voltage changes slowly over long periods of time for environ-
mental factors, but changes quickly over short periods of time for actual smoke.
Initial System Power-Up
When a new or modified Zeus configuration is loaded into a system, the FireFinder-XLS
PMI/PMI-2/PMI-3 goes through an initial system power-up. FireFinder-XLS does not
keep the IEC option where it was formerly applied when this new system powers up.
The IEC memory re-initializes, and then FireFinder-XLS begins adjusting the alarm
thresholds wherever IEC is selected in the new Zeus configuration.
Alarm
Threshold Voltage
Analog Voltage
0 Volts
SENSITIVITY
VOLTAGE
