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CTI technology is an enhancement to standard digital linear heat detection operation. Where traditional dig-
ital linear heat detectors have a single mode of detection, CTI digital linear heat detectors add a second mode
of detection. This second mode of detection utilizes the thermo-electric effect to measure the temperature at
the short circuited point of the detector to confi rm a true alarm condition exists.
Figure 3 - The Thermo-electric Effect is the production of an electromotive force (Voltage) in a loop of
conductors consisting of two dissimilar materials. When two junctions in the conductors are maintained at
different temperatures a voltage is produced relative to the temperature difference between the two junctions.
This voltage is used to measure temperature in devices called Thermocouples.
CTI™ Digital Linear Heat Detector Operation
Figure -3
Figure 4a - CTI digital linear heat detectors are constructed of a twisted pair of dissimilar metal spring con-
ductors coated with a thermoplastic coating designed to soften at a specifi c temperature. An initiating device
circuit monitors a length of this detector installed in the area to be protected.
Conductor A
Measurment
Junction
Conductor B
Voltmeter
+
-
Reference
Junction
Measurment
Device
Thermocouple
HEAT
This very reliable method of detection has been in use for over 75 years in the fi re protection industry; however
the possibility of mechanical damage causing a short circuit does exist. A short caused by mechanical damage
will produce a false alarm condition therefore care needs to be taken during installation and design to locate
the detector in areas it is least likely to be subjected to physical damage.
Monitor
Circuit
End Line
Resistor
Heat Sensitive
Insulation
Normal
G
Figure -4a
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