WEB: http://www.centsys.co.za General information e-mail: [email protected]
Page 4
RELAYS
(PRESENCE
OR PULSE)
PRESENCE
RELAY
N/O
N/O
N/C
N/C
PULSE
RELAY
VEHICLE
PRESENT
NO VEHICLE
LOOP FAULTY
NO POWER
Closed
Open
Closed
Closed
Open
Closed
Open
Open
Pulse closed
Open
Open
Open
Pulse open
Closed
Closed
Closed
RELAY FUNCTIONALITY:
ROAD
EDGE
TRAFFIC DIRECTION
45° CROSSCUT
FEEDER
1M
300mm
300mm
ROAD SURFACE
30 - 50 mm
4mm
SLOT
SEALANT
WIRES
CENTURION SYSTEMS (Pty) Ltd
148 Epsom Avenue, North Riding,
Randburg, South Africa
Tel: +27 (0)11 699-2400 Fax: +27(0)11 704-3412 or
+27(0)11 462-6669 (Sales)
Share call number: 0860-103-726
1184.D.01.0002_3 LD200 Series Vehicle Loop Detector
INSTALLATION GUIDE
1.
The detector should be installed in a waterproof housing as close to the loop as possible.
2.
The loop and feeder should be made from insulated copper wire with a minimum cross-sectional
area of 1.5mm². The feeder should be twisted with at least 20 turns per metre. Joints in the wire
are not recommended and must be soldered and made waterproof. Faulty joints could lead to
incorrect operation of the detector. Feeders which may pick up electrical noise should use
screened cable, with the screen earthed at the detector.
3.
The loop should be either square or rectangular in shape with minimum distance of 1 metre
between opposite sides. Normally 3 turns of wire are used in the loop. Large loops with a
circumference of greater than 10 metres should use 2 turns while small loops with a
circumference of less than 6 metres should use 4 turns. When two loops are used in close
proximity to each other it is recommended that 3 turns are used in one and 4 turns in the other
to prevent cross-talk.
4.
Cross-talk is a term used to describe the interference between two adjacent loops. To avoid
incorrect operation of the detector, the loops should be at least 2 metres apart and on different
frequency settings.
5.
For loop installation, slots should be cut in the road using a masonry cutting tool. A 45° cut should
be made across the corners to prevent damage to the wire on the corners. The slot should be
about 4mm wide and 30mm to 50mm deep. Remember to extend the slot from one of the corners
to the road-side to accommodate the feeder.
6.
Best results are obtained when a single length of wire is used with no joints. This may be
achieved by running the wire from the detector to the loop, around the loop for 3 turns and then
back to the detector. The feeder portion of the wire is then twisted. Remember that twisting the
feeder will shorten its length, so ensure a long enough feeder wire is used.
7.
After the loop and feeder wires haven been placed in the slot, the slot is filled with an epoxy
compound or bitumen filler.
