14
DPT260
5.6 - LAYING OF INDUCTIVE LOOPS
If the system is set on automatic mode (bollards rise only after the occurred transit of a vehicle) it is
necessary to install inductive loops to detect metallic masses (vehicles).
Inductive loops are suitable for two different applications:
• “Limited” protection of the bollards
(PIC. 12 - PIC. 13)
. In this case a single inductive loop is installed around the
bollards, it avoids the raising in case a vehicle is over the bollards or in the immediate surroundings.
• “Extended” protection of the bollards
(PIC.14)
. In this case two inductive loops are installed, one before and one
beyond the bollards; a vehicle in motion is detected about 3m before the bollards and the detection is enabled up
to 3m beyond the bollards. This function let the system detect in advance any other vehicle in transit and avoid any
eventual accident.
Notes on the installation:
1.
Standard inductive loops are 9,60m long (usually m 1,80 x 3,00); therefore it is possible to take into account other
dimensions.
2.
The inductive loop is made of a special cable of 9mm diameter and it is suitable for the direct laying into the
ground, without any sheath nor protection.
3.
It is essential to check the presence of electro-welded meshes into the ground. If this is the case, you shall remove
the mesh for about 25cm beyond the perimeter of the inductive loops
(PIC. 16
).
4.
Inductive loops shall be laid with “rounded corners”
(PIC. 16 - PIC. 17)
.
5.
Inductive loops shall be laid approx. 7cm under walking level. In presence of cobblestones or similar, of 10mm
thickness or greater, it is necessary to flatten out that material in order to allow the laying of the loops at the
suggested depth. As an alternative, it is possible to lay the inductive loop between one cobble and onother like a
“Greek fret”.
6.
Inductive loops are supplied with a junction box
(PIC. 15)
which is connected to to the control unit through a line for
signal transmission. This line is made of a special insensitive cable which has a standard length of 15m (it is
possible to purchase lines of greater lengths).
7.
Inductive loops can also detect an outbound vehicle and therefore carry out the automatic lowering of the bollards.
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