User's Manual

301UM0031_01 TD136 Enhanced Vehicle Detector User Manual Page: 9 of 29
3. OPERATING INSTRUCTIONS
3.1 Hardware Set-up
The TD136 Enhanced Vehicle Detector is a single channel traffic detector designed to be shelf or DIN
rail mounted with the controls and visual indicators at the front and wiring at the rear of the enclosure.
The power, loop and relay outputs are all connected to the single 11-pin plug, which is mounted at the
rear of the enclosure.
3.2 Switch Setting Selections
3.2.1 Frequency Switch
The frequency switches are the lower two switches, numbered 1 and 2. There are four frequency
selections and are set out as follows:
SW2
SW1
Off
Off
High
On
Off
Medium
-
High
Off
On
Medium
-
Low
On
On
Low
The frequency switches allows the loop to be shifted higher or lower depending on the switch position.
The frequency of the loop is determined by the loop size, and the frequency of the switch simply
causes a frequency shift on the loop.
Where more than one detector is used the detectors must be set-up to ensure that there is no cross-
talk (interference) between the detectors. This can be achieved by ensuring that the loops of the two
detectors are spaced sufficiently apart (approximately 2 metres between adjacent edges) and also
ensuring that the detectors are set to different frequencies.
As a general rule, the detector connected to the inductive loop with the greatest inductance should be
set to operate at the lowest frequency. Loop inductance increases as loop size, number of turns in the
loop and feeder length increases.