REFERENCE
9.
This guide is written from a design perspective,
but installation workmanship practices are
equally important to insure proper operation
and long loop life. The best way to insure a
quality installation is to employ a professional
installer experienced with detector loops. A
few important practices are: See Figure 70
z
The slot in the surface of the road should be cut
¼-inch wide x 1½-inch deep (6.3mm x 38.1mm).
z
The corners of the cut must be at an angle or
core drilled to relieve stress on the wires.
z
After the wire is installed, the slot must be
completely backfilled with a non-hardening
sealer. If the loop wires are able to move in the
slot after the sealer has set, the detector may
give false calls.
Figure 70. Loop Sealant
Detector Logic
HySecurity recommends that vehicle detectors
be used for free open and obstruction sensing
logic only. Because of their slower speeds, closing
logic is a poor choice for security gate systems.
Since there are several ways that the gate may
be left standing open and because there is a loss
of safety, our circuit has not been designed to
accommodate “detect to close” logic.
Loop Diagnostics
The following tests cannot guarantee a functioning
loop, but failure of either test means that the loop
is definitely suspect, even though it may still be
functioning at the time.
1.
Test the resistance of the loop and lead-in wire.
It should not exceed 4 Ohms.
2.
Test the resistance between the loop and
earth ground with a 500V Megohm meter. It
should be 100 Megohms or more. Loops may
function at 100 Megohms or less but will not
be reliable (e.g. when the ground is wet from
rainfall). Low resistance indicates broken or
moisture saturated insulation. This is common
if inappropriate wire insulation has been used.
112
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SWINGSMART DC PROGRAMMING AND OPERATIONS MANUAL
MX3640-01 REV. D ©2018
