Cardin LD-3 Instrucciones De Uso Y De Programación página 12

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The performance of the LD3 loop detector is to a large extend dependent on the installation. In order to get the best
performance from the LD3 the following installation procedure shoul be strictly followed.
CAUTION In general inductive loop detectors are reliable vehicle detectors, however they cannot be used as safety
devices. Firstly, inductive loop detectors do not detect humans and other non-metallic objects . Secondly, inductive
loop detectors have a limited detection range, that is they can only detect metal objects within a certain distance of
the sensing loop's area.
POSITIONING THE COIL
After having decided the function the the detector LD3 is going to carry out, take the following variables into account:
- The road surface and foundation must be in good condition as even a dislocation of the wires making up the inductive coil by
1 mm can activated the detector.
- All metallic objects that are located in the vicinity of the coil can adveresely effect the detector and consequently its correct
operation.
The vicinity of these objects will mainly cause a reduction in sensitivity, or erroneous activation. More rarely it may also
impede the disactivation of the detector once the vehicle has passed.
Tarmac or concrete road surafaces that have been reinforced with metallic structures can cause teh aforementioned effects.
SHAPE OF THE COIL
The shape of the inductive coil may be rectangular or square with 45 degree indents on the four corners (fig. B). This will allow
for the expansion of the embedded conductor wire when faced with temperature variations without causing damage.
If the width of the inductive coil is greater than 1 metre, it's sensitivity in the at the centre will decrease.
To improove the operation of the LD3, the inductive coil should be made in such a way as to guarantee that at least two sides
are below the vehicle simultaneously.
If you are unsure of the shape and dimensions to be used, we advise you to construct a trial to test on the surface of the road.
Lay out the coil and fasten it to the road surface by inserting nails into the corners of the shape.
You should carry out tests using vehicles which are both smaller and larger than the thoase you intend to detect.
Fig. B indicates the shape to be adopted.
CUTTING THE ROAD SURFACE
Using a masonry saw, cuts slots 15-30 mm (Fig. B) deep into the road surface to accommodate the sensing loop wires. From
one corner cut leading back to the LD3 to accommodate the feeder wires . Note the feeder wires will be together s the slot
width must be able to accommodate them.
WIRING THE SENSING LOOP
The sensing loop is constructed using a single length of copper stranded insulated wire with a minimum conductor area of 1.5
mm. The wire is lad around the sensing loop a certain number of times, depending on the length of the sensing loop's
perimeter and its relative position to other sensing loops and metal objects.
Each layer of wire is known as a "turn".
If two sensing loops of similar size and shape are be located within 2 meter's of each other and extra turn of wire should be
added to one of them.
If the road contains steel reinforcing or a metal object is located close to the sensing loop, an extra turn should also be added.
Use the table in Fig. C as a guide.
Starting at the LD3, run the wire along the feeder slot then around the sensing loop slot the required number of turns and back
along the feeder slot to the LD3 (Fig. D).
Cut the wire to length and twist the two feeder wires together with no less than 1 twist per 50mm. The feeder wires should be
connected to the LD3 at the two terminals blocks labelled "LOOP".
If more than one pair of feeder wires are able to be run in the same slot it is advisable to shield each feeder wire pair . Note: the
shield should be grounded at the LD3 end only.
ELECTRIC CONNECTIONS (Fig.E)
IMPORTANT The LD3 must have it's own power supply
The connection between LD3 and the coil should be as short as possible and should not never exceed 2-3 m.
Three different potential free outputs are available with the following functions:
Give the Operation the loop detector is to perform, and the control interface requirements of the access controller, use the
following information and fig. 2 to wire the LD3 output terminal blocks to the access controller.
The LD3 has three functional outputs provided via relay contacts. The functional output s provided are:
- OUT 1 ENTRY, this relay will be pulsed for about 1 sec. each time a vehicle is detected. Approaching the sensing loop.
- OUT 2 PRESENT, this relay will be activated whenever a vehicle is detected over the sensitive loop.
- OUT 3 EXIT, this relay will be pulsed for about 1 sec. each time a vehicle is detected leaving the sensing loop.
The new LD3 also features a direction detection function which can be activated by moving dip 2 to ON and connecting a
second device to the input marked 'INPUT SIGNAL' (metallic mass detector or photoelectric cells shown in the example fig.
E).
LD3 monitors the sequence and activates the output as follows:
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