VEK FG2-1
operating instructions
FEIG ELECTRONIC GmbH
12/99
17
Metallic objects within
loop area
Verification: use diagnostic device VEK FG2 in
detuning
position to check frequency fluctuations and
-jumps caused by movements of the metallic object.
Note:
If metallic objects (e.g. manhole covers, grates, loose gates etc.) are surrounded by the loop,
their
movements may cause detunings of the resonant circuit. Should there be permanent, negative
frequency changes, the system may not recognize vehicles which do only cause minor detuning.
Remedy: - re-install loop, so that the metallic object is now outside the loop field.
- replace the metallic object by a non-metallic one.
- prevent movements of the metallic object.
(if necessary, fix manhole covers and grates by welding)
Detector does not respond to lorries
Possible reasons
Measures
Sensitivity is too low
Verification: cross the loop with a lorry and check the detuning with diagnostic device VEK FG2.
Due to the great distance between the bottom of the car body and the loop, the detuning
caused by
Lorries is lower than the one caused by passenger cars. Therefore, the responsiveness of the
Detector has to be higher.
Remedy: increase sensitivity
Unfavourable loop
geometry
Verification: cross the loop with a lorry and check detuning with diagnostic device VEK FG2 .
Remedy: choose a loop geometry which is completely covered by the vehicle.
Insufficient mechanical
loop solidity
Verification: tap the surface above the loop with a beam and observe diagnostic device VEK FG2 in
detuning
Position with regard to possible frequency jumping or permanent detuning.
Note: Changes in the loop geometry may cause positive as well as negative detuning of the detector.
Positive detuning may lead to a permanent seizure of the detector. In case of negative
detuning, the
detector becomes more sensitive. Extreme frequency jumps may lead to a re-alignment of the
detector.
Remedy: -please make sure that the loop is of sufficient mechanical solidity; there must not be any defor-
mations in the loop geometry when crossing it.
-
The loop must not move compared to the ground armouring.
-
For installation under paving stones, please do always use finished loops.
Influences caused by
armouring or metal foil
Verification: cross the loop with a vehicle and check detuning with the help of diagnostic device VEK FG2 .
Note: the loop is deadened by strong armouring or metal foil which is located in the concrete floor under
the loop. Such loops have a reduced sensitivity.
Remedy: - influences caused by the armouring may be leveled out to a certain extent by increasing the
detector’s responsiveness.
- spare the metal foil in the loop area.
Metallic objects in loop
area
Verification: use diagnostic device VEK FG2 in
position to check frequency fluctuations and
-jumps caused by movements of the metallic object.
Note:
If metallic objects (e.g. manhole covers, grates, loose gates etc.) are surrounded by the loop,
Remedy: - re-install loop, so that the metallic object is now outside the loop field.
- replace the metallic object by a non-metallic one.
- prevent movements of the metallic object.
(if necessary, fix manhole covers and grates by welding
Detector only responds short-term or not at all
Possible reasons
Measures
Sensitivity has not been
adjusted
Verification: cross the loop with a vehicle and check detuning with diagnostic device VEK FG2..
Remedy: Adjust the sensitivity of the detector. (see charts under „
Unfavourable loop
geometry
Verification: cross the loop with a vehicle and check the detuning with the help of diagnostic device VEK
FG2 .
Remedy: choose a loop geometry, which is completely covered by the vehicle.
Loop area is too big
Verification: cross the loop with a vehicle and check detuning with the help of diagnostic device VEK FG2.
Remedy: - install a smaller loop.
- choose another loop geometry.
- interconnect several smaller loops.
Caution: sensitivity loss !
