Section 3 – General System Information
Telemotive Laser Guard Instruction Manual – October 2009
7
3-1.
Class 1 Laser Device
The Telemotive Anti-Collision System contains a
Class 1 laser because of this no special protection on
the part of the installer or user is needed. However, it
is recommended that no one look directly into the
laser with their eye close to the lens of the laser unit.
Do not open the laser unit to service it since there are
no serviceable parts inside.
3-2.
Laser Anti-Collision System Description
Telemotive's Anti-Collision System measures the
distance between the laser unit's lens and its
companion retro-reflective target by means of pulse
timing techniques that allow for very accurate
measurements. The laser communicates with the
range detector module by means of a 4 mA to 20 mA
current loop. This type of communications link has
very high noise immunity and provides the necessary
accuracy for a collision avoidance system. The laser
used in the Laser Guard system is set to measure
distances from 5 ft. to 150 ft. with an output current
of 4 mA at 5 ft. and 20 mA at 150 ft. Should a fault
occur within the laser unit, the output will drop to 0
ma. The laser unit uses a modified light beam making
system alignment very easy. On the back of the laser
are two LEDs. The red LED indicates a laser self-
check when power is first applied, and a laser failure
if it stays on. The green LED displays laser received
signal strength and is used for alignment purposes.
The laser unit is connected to range detector and
power supply modules by means of a shielded
twisted pair cable.
A rugged, fully adjustable (azimuth/elevation) mount
is also supplied with the system, along with a
reflective target. The target is mounted on the wall or
other crane that you wish to avoid hitting.
The range detector module contains three fully
adjustable range detectors; a fault detector, and two
out-of-sequence detectors. The range detectors are
adjustable from 10 ft. to 150 ft. where the first point
detector is set for the distance that you want the first
stage of crane deceleration to take place. Range
detector two sets stage two of deceleration, and the
third detector is used to set the point where you want
the crane brakes to be applied. The relationship
between these points is as follows:
150 ft.
≥
RANGE 1> RANGE 2> RANGE 3
≥
10 ft.
If the above sequence is not maintained, an out-of-
sequence error will occur which will dropout the
third range point and the fault detector. This will stop
the crane and prevent it from being moved in the
protected direction until the sequence is corrected.
One or both of the out-of-sequence LEDs will be on
identifying which range detectors must be readjusted.
Adjusting the third range detector for less than 10 ft.
will cause the third range detector and the fault
detector to drop out. Setting the other range detectors
for less than 10 ft. will cause an out-of-sequence
error because the third range detector cannot be set
for less than 10 ft. Each range detector and the fault
detector have a form C relay output that is normally
energized until a range point or a fault is detected.
The markings on the range detector module show the
de-energized state of the relays. Also contained in the
range detector unit are the power supply and power
input modules.
3-3.
Optical Path Fault Detector
This Laser Anti-Collision System contains a Laser
Optical Fault Degradation Detector. When this
system detects a loss in the optical path due to dirty
optics, dirty target, obstructions between the two or
misalignment of the laser and its target, it will
produce a 30 second fault. This will cause the fault
relay and the third range point relay to drop out for
30 seconds. After this 30-second period, the system
will return back to normal operation until the fault is
detected again. This is the only fault condition that
lasts 30 seconds, (all other fault conditions do not
time out) thereby making it easy to determine that an
optical path problem has occurred and maintenance is
needed to clean the lenses of the laser unit and/or the
target. In some instances, the laser may have become
loose and may need to be realigned. This unique
circuitry performs a dynamic test every time the first
range point is detected. It will produce the above
described fault condition any time that this point is
detected approximately 10% or more below its preset
range.
3-4.
Fault Relay
A separate form C relay is provided to drive a
warning light or enunciator in the event of a fault.
The relay is normally energized and if a fault occurs
the relay switches. Faults can be the loss of the
target, setting out of sequence, laser head failure, or
circuit failures.
