304UM0001 Rev 00
PD160 Enhanced Series User Manual
Page: 12 of 39
situation. If the situation is very close to the limit, it is possible that it might tune as the
drift or noise goes back over the threshold and the unit goes into detect just as it
tunes. In a noisy environment, this can be prevented by retuning and if the situation persists to
decrease the channel sensitivity or increase the relay output delay.
The PD160 Detector can handle environmental conditions that cause the frequency to drift up at a rate
of approximately 1 %
∆
L/L per minute. Above this, false detects can occur.
If the drift is high it could be a possible fault with the loop or feeder cable. Possibly the wire insulation
has deteriorated and moisture is causing a short to earth or wires of the loop are no longer
encapsulated and are moving.
For more information about Frequency drift refer to the “Theory of Application” section in the
Diagnostic Unit DU100 User Manual Document No. 895UM0001.
3.2.3 Sensitivity
The sensitivity of the detector determines the change of inductance
necessary to produce a detect. The PD160 provides a much larger
range of sensitivities, with fifteen available settings.
Defined as the percentage change in inductance, the sensitivity
selections range from 0.01% which is the highest sensitivity, to 5.0%
as the lowest sensitivity.
Setting
0.01%
Highest
0.02%
0.03%
0.04%
0.05%
0.06%
0.07%
0.08%
0.09%
0.10%
0.20%
0.50%
1.00%
2.00%
5.00%
Lowest
ASB
Automatic Sensitivity Boost
For a standard loop of 1.0 metres by 2.0 metres with 2 turns (circumference less than 10 m) and a ten
metre feeder cable the above right table shows typical sensitivity values for different vehicle types. For
more information about Sensitivity refer to the “Theory of Application” section in Diagnostic Unit
DU100 User Manual Document No. 895UM0001.
3.2.3.1
Automatic Sensitivity Boost
Automatic sensitivity boost (ASB) is a mode which alters the un-detect level of the detector, and can
be toggled on or off via the sensitivity menu.
ASB causes the sensitivity level to be boosted to a maximum on detection of a vehicle, irrespective of
current sensitivity level and maintained at this level during the entire presence of the vehicle over the
loop. When the vehicle leaves the loop and the detection is lost, the sensitivity level reverts to the pre-
selected level.
VEHICLE TYPE
%
∆
L/L
Metal Supermarket Trolley
Bicycle
0.04
Motorbike
0.12
Articulated Truck
0.38
Four Wheel Drive
0.40
5 Ton Tip Truck
0.45
Motor Car
> 1.00
Forklift
> 1.00
