DSP-50 User Manual
Page 20 of 27
DSP50_MAN_A
5.
Installation
Detector Installation
Location:
The detector should be installed in a weatherproof location that is near the loop. Ideally, a technician
should be able to see the loop and the detector at the same time.
Mounting:
The detector will function when mounted in any orientation. If the operator does not have a
connector for the detector to directly plug in to, an adapter board will be needed (RK-1 or RK-3). Mount the
adapter board such that the switches and LEDs on the detector will be easily accessible for configuration and
troubleshooting.
Wiring:
If plugging the detector in to the operator, you should be certain that the operator pin out for its
connector is the same as that of the DSP-50 detector and that the voltage supplied to the detector is between
10 and 30 volts DC.
If using an adapter board, terminate all wires on to the adapter board before plugging to detector into the
board. Wire nuts should never be used at any point in the loop circuit itself. All loop connections should be
crimped or screw terminals at a minimum and soldered for best long-term reliability.
Special attention should be paid to ensure that the loop wires remain tightly twisted together. An air gap
between the two wires for a loop may cause the detector to lock up if the wires are disturbed.
Remember that the DSP-50 uses solid-state outputs and can only sink current. Therefore, if you want to drive a
relay coil with an output, the other side of the relay coil must be connected to an appropriate voltage (for the
coil) positive DC supply. Using an AC relay is not possible and may damage the detector. The detector has
snubber diodes built in for all of the solid-state (open-collector) outputs in case they do drive a relay coil.
Loop Installation
The reliability and overall performance of the detector are greatly dependent on the loop itself. Several factors
go into a good loop installation: type of wire used, loop configuration, and installation practices.
Type of Wire Used:
The wire used for wiring the loop should have a jacket of cross-linked polyethylene or
similar material that has very low moisture absorption properties. This would be a wire with an XLP jacket such
as XHHW. THHN or similar wire types should never be used for loop wire.
The gauge of the wire to use depends on two factors: Distance in cable feet from the loop to the detector and
stresses the wire may see. The gauge of the wire can be 20 AWG as long as the detector is within 50 feet of the
loop in cable distance. For 50 to 100 feet, use at least 18 AWG wire. At greater than 100 feet, use a 16 AWG
wire at a minimum. If the loop is installed in asphalt and there will be heavy vehicles or stopping and starting
vehicles in the loop area, a 14 AWG or 12 AWG should be used to provide additional strength to the loop. This
helps increase the life of the loop in areas where the asphalt may slowly move and/or deform due to wear.
