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To prevent any difficulties in installation and use, it is important to
take into account all points which could affect successful operation. These are addressed
below:-
- 1. Siting
- Position beacon lamps where the maximum effect of their signal is utilised. Avoid
positions of strong sunlight unless there is no alternative. Where relevant, add an extra
beacon lamp in the appropriate places to confirm the signal. As an example, where a beacon
lamp may be out of sight (for example in a tunnel frequented by fast moving forklift
trucks), it is worthwhile adding an extra beacon inside the tunnel to safeguard other
personnel.
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- 2. Orientation
- Carefully follow the instruction sheet supplied with the beacon lamp(s).
It is recommended in all cases that the beacon lamp be mounted vertically upwards (dome
lens on top). This is vital where continuous operation is required of the beacon lamp.
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- Where continuous operation is not required, and the instruction sheet allows for this,
then the beacon may be mounted inverted or on its side. Recommendations of time-energised
and recovery-time-afterwards for particular models can be obtained by contacting your
nearest Sales Point.
- It is important to remember that mounting in positions other than recommended vertically
upwards (dome lens on top) can impair the protection against moisture and water.
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- 3. Mounting
- Mount the beacon lamp on an approved bracket. Choose the most suitable bracket to assist
in limiting any vibration which may result from wind or structural movement. If the beacon
lamp is being mounted on a vehicle lacking sprung suspension, it is recommended that
anti-vibration mounting be applied during installation to give a measure of beacon
protection. Recommendations can be obtained from your nearest Sales Point.
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- 4 Protection
- Check in the catalogue information, or on the website www.deegee.com, to confirm the
environmental protection class of the beacon lamp that you are installing. Ensure that the
protection is not impaired by installation work that you may do, and that any drilled
entrances or un-used holes are blanked off or sealed appropriately to maintain the IP
rating effective. Where a product is provided with threaded conduit entrances, seal the
joint with suitable PTFE tape wrapped around the conduit or gland threads.
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- Where an earth connection is to be maintained, it is vital that appropriate tests be
carried out after installation to ensure that the use of the tape has not impaired the
earth continuity.
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- 5. Voltage Drop
- The design of the installation must at all times take account of the potential for
voltage drop and the effect this can have on the operation of the beacon lamp(s).
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- All cables have the ability to drop voltage, especially when carrying high current
through them. Advice must be taken from the cable manufacturer concerning the cable size
(cross sectional area). Increase this if necessary to overcome any opportunities for
substantial voltage drops due to the current being drawn. Ambient temperatures outside
those recommended by the cable manufacturer must also be taken into account, as the cable
resistance may be increased by a higher-than-allowed temperature, so also creating voltage
drop.
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- When connecting beacon lamps, keep the cable run from the power source to the beacon(s)
to the absolute minimum. Where the voltage of the beacon lamps is, for example 12V or 24V,
the current drawn by the beacon lamp will be high in proportion to mains voltage versions,
so cable sizes must be greater.
- Calculate, using OHMS LAW (see below) what current is going to be drawn by each beacon
lamp. In the case of a xenon where the current varies, adopt the maximum current inrush as
the one to be covered.
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- Where multiple beacons, particularly those being operated in synchronism, are being
installed, avoid 'daisy-chaining' the beacon lamps to the supply. This also applies where
multiple rotating flashing models are being installed to operate at the same time from the
same supply.
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- Instead of 'daisy-chaining', use a 'star' connection to the beacon lamp from the power
supply source. In this configuration each beacon has its own cable from the power source,
rather than being part of a 'chain' of lamps all fed one after the other. Keep the length
of cable the same from the power source, to each beacon lamp ensuring similar volt drop
applies to each beacon lamp. The volt drop should be of course be kept to an absolute
minimum.
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- Where long distances of cable cannot be avoided, repeater power supply sources should be
adopted and measurements taken at each beacon when in operation. When all are operated,
ensure that each beacon in an installation has the equivalent and correctly rated voltage
applied.
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- Knowledge of other devices on site which could cause high voltage variations to be
apparent is important.
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- When calculating the voltage drop in the cabling, remember that it is important to
expect a drop in the positive lead and the negative lead, or in the line and neutral lead
of an AC supply. See the worked example under section 6.
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- 6. Calculations and Examples
- When a current travels through a resistance, an amount of voltage, equal to the product
of the current in amperes and resistance in Ohms, is dropped across the resistance. This
is known as Ohms Law. As cable has resistance, any current flowing through it will incur a
volt drop.
- Typical resistive values for cable
CSA Ohms/ Ohms/
mm² metre kilometre
0.25 0.0836 83.6
0.35 0.0561 56.1
0.50 0.0401 40.1
0.75 0.0247 24.7
1.00 0.0200 20.0
1.50 0.0137 13.7
2.00 0.0099 09.9
2.50 0.0082 08.2
(All figures typical at 20°C)
- To calculate volt drop in a cable use the following formula: -
- Volt Drop = 2LRI
- Where: -
2 is both legs of the supply cable.
L is the length of cable-run in metres.
R is the resistance per metre of the cable (see table above) in Ohms.
I is the maximum drawn current in Amps.
Example
25-metre run of standard 16/0.2 wire (0.5mm² cross-sectional area) supplying power to 3
beacons. Each beacon drawing a maximum of 250mA
First calculate the volt drop: -
2LRI = 2 x 25 x 0.0401 x (3 x 0.25)
= 1.5V Drop
Therefore, if the power supply were producing 24V, the voltage at the beacons would be: -
Original Voltage - Volt Drop = Voltage at Device
24 - 1.5 = 22.5V at the beacons
To decrease the amount of volt drop, either:
1 Increase the size of the cable by changing the cable for a larger
size.
2 Add a power supply unit closer to the powered devices.
3 Reduce the load by selecting units with lower power consumption, e.g.
consider Xenon Strobes instead of Rotating Mirror beacons, or LED beacons instead of
Strobes.
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- 7. Temperature
- Extremes of temperature must be taken into account when choosing or installing beacon
lamps. Extremely low temperatures can be as difficult to compensate against as high
temperatures. Very low temperatures can cause filament lamps to fracture because the lamp
filament becomes increasingly brittle. Both high and low temperatures can cause increased
voltage drop in cables as detailed in section 5, and this should therefore be calculated
in line with the recommendations from the manufacturers of your cable. Take careful note
of the temperature tolerance allowances given in the data information contained in our
catalogue, or obtainable from our web site www.deegee.com.
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- 8. Maintenance
- Even if you are not responsible for the ongoing maintenance of the product, ensure that
the equipment can be accessed and opened for maintenance. Install an isolator to
completely make the beacon lamp electrically safe for maintenance work to be carried out.
If possible choose beacon lamps which are of the low maintenance variety.
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- Keep necessary spare parts such as filament lamps and fuses readily available and in
stock. If the beacon lamp is a xenon strobe version in continuous use, it is recommended
that a spare exciter be kept available to make for easy exchange. The circuitry of the one
requiring maintenance should be taken to a place of safety to be worked upon.
Whilst these recommendations are made in good faith, it must be clearly understood that
errors and omissions are excepted and the company and any of its servants cannot be held
responsible for problems resulting following any recommendations given. At all times,
installation and maintenance of deegee beacon lamps should only be carried out by
qualified personnel, who are well proven in the safe application and usage of electrical
equipment and installation work. |
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