User's Manual

306UM0002 - 01 TD236 Enhanced Detector User Manual Page 27 of 35
8.2 DU100 – Detector Diagnostic Unit
The DU100 Diagnostic unit is a hand-held test instrument that has been designed to
operate with the TD236 Enhanced detector to provide installation/service personnel with positive
verification of the correct operation of the vehicle detector and its installation.
The following parameters may be verified using this instrument:
1. Detector type and version
2. Loop status Display of loop frequency and magnitude of current change
of loop inductance %∆L/L.
3. Frequency Readout of the actual loop operating frequency and the
magnitude of the frequency drift since the last re-tune.
4. Sensitivity Displays the Minimum and Maximum changes of Inductance
%∆L/L that caused a detect since the last re-tune.
5. Status Displays the current status of the detector i.e. Undetect,
Detect, Open circuit, Short circuit or Indeterminate.
6. Time The time in days and hours since the last re-tune and the
reason for the last re-tune i.e. Reset: manual or power failure, Loop
short circuit, Loop open circuit, Indeterminate or an Inductance
change of greater than 15 % ∆ L/L (typical).
This historical information is invaluable in providing information
about intermittent faults.
7. Crosstalk Allows for the comparison of the operating frequencies of
Detector loops in close proximity to each other. If the operating
frequencies are to close the DU100 test will indicate a failure.
For further information refer to the Diagnostic Unit DU100 User Manual Document No. 895UM0001.
It is highly recommended that after installation of a detector (or if the loop has been changed in any
way) that the DU100 Diagnostics Unit is used to verify the correct operation of the detector. A record
of the readings should be kept so that if there is a problem in the future a comparison can be made
to identify what has changed. The form in Appendix C could be used to record these readings.
8.2.1 Interpretation of the DU 100 readings
8.2.1.1 Frequency
For the TD236 Enhanced Detector the Minimum frequency is 24 kHz and the Maximum
frequency is 78 kHz
If a 20 µH loop is connected directly (no feeder cable) to the Detector and the Frequency
switches are set to “High Frequency” the typical frequency would be 78 kHz
If a 1000 µH loop is connected directly (no feeder cable) to the Detector and the Frequency
switches are set to “Low Frequency” the typical frequency would be 24 kHz
If the Frequency reading from the DU100 is close to the Minimum Frequency the inductance of
the LOOP is too large – you need to remove turns from the loop
If the Frequency reading from the DU100 is close to the Maximum Frequency the inductance of
the LOOP is too low and you need to add turns to the loop