7.4 Leads to luminaires. Osram HQI-E 150 W/NDL CL
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At the end of the lamp service life, higher temperatures than normal can occur in the pinch area caused by outer bulb discharges. The socket must be rated accordingly (see also chapter 6.2.1 Leaking arc tube).
When replacing such lamps, the socket must always be checked for signs of damage and replaced if necessary, because a damaged socket would also damage the new lamp.
• Rated current and rated voltage
The socket must be chosen according to the lamp parameters. The rated current in this case is the highest continuous load current, and the rated voltage is the highest voltage for which the socket is designed.
contact, as otherwise the socket contacts can be damaged.
7.4 Leads to luminaires
The lead cables to the luminaires must be rated for their conditions of use, taking account of adequate heat and UV-resistance, mechanical strength, electric strength and current carrying capacity, as well as giving due consideration to the effect of cable lengths
(e.g. when remote mounting is required). Cable resistance grows linear to cable length. The resulting voltage drop across the cable reduces the effective supply voltage. The effects are described in chapter 3.1.3
“Influence of deviations in supply voltage”.
CAUTION! Certain sockets such as G12 and E27 are used for different wattage levels. When inserting or exchanging lamps make sure that the right lamp for the respective ballast is chosen. Otherwise the lamp is operated incorrectly, and the socket may possibly not be rated for the deviating operating conditions.
Various factors must be considered when choosing leads in the lamp circuit:
• The voltage drop across the lead depends on the flowing current and can be reduced by using cable with a larger cross section.
• Fastening parts
The connection parts, e.g. blade terminals, must be chosen according to the requirements (e.g. temperature, current load, corrosion resistance).
• It should also be borne in mind that cable resistance increases with higher ambient temperature.
The resistance of a copper cable rises by about
10% for an increase in temperature of 25 °C.
• Consideration must be given to the voltage drop in the outgoing and incoming cable.
• Connection leads
The connection leads must be rated accordingly for the conditions of use with regard to heat and
UV-resistance, mechanical strength, electric strength and current carrying capacity.
PTFE leads are normally not suitable to handle ignition voltage. In practice, silicone-insulated leads with 3.6 mm outer diameter have proven effective for discharge lamps. For lamps with immediate hot re-ignition, silicone insulation 7 mm thick should be used together with fiberglass inlay.
While the lamp is starting up, it is possible for the start-up currents to briefly exceed the nominal values, which must be taken into consideration when rating the socket. Up to 1.5 to 2x the operating current can flow during the start-up phase
(within the first 5 minutes of operation).
• Isolation of Contact Connections
Care must be taken to electrically isolate the connection contacts in the installation procedure if this is not safeguarded by the socket alone.
• 230 V systems are more sensitive to additional line resistance than 400 V systems.
In applications demanding the lowest possible colour scattering, the supply conditions should be approximately the same, i.e. supply voltage or line resistance should be equivalent.
7.5 Maintenance of lighting systems with metal halide lamps
Since March 2003, the EN 12464-1 standard applies to interior lighting systems throughout Europe. If a lighting system is being planned according to this standard, it is necessary to draw up a maintenance plan. This has to take into account influences causing a drop in luminous flux in the system during the course of the service life, such as dirt depreciation of luminaires and the room itself, together with the aging of the lamps and lamp failures. The maintenance factor replaces the previous planning value.
• Lamp pins
Only use lamps with clean metallic contacts.
Oxidized contacts result in high transition resistances and generate high operating temperatures.
The surface of the lamp pins must be smooth and must not show any visible traces of mechanical machining in the area of contact with the socket
Maintenance factor MF = LLMF x LSF x LMF x RMF
LLMF = lamp luminous flux maintenance factor
LSF = lamp survival factor
LMF = luminaire maintenance factor
RMF = room maintenance factor
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Example for a maintenance plan
Maintenance plan
Only regular maintenance can ensure compliance with the stipulated illuminance levels in the EN 12464 standard for the lighting system. The following maintenance intervals must therefore be followed.
Room
Type of surrounding:
Maintenance interval:
Normal every 2 Years
Luminaire XXX
Influence of reflections from the room surfaces:
Luminaire characteristics:
Reflector type:
Lamp type :
Ballast:
Operating hours per year:
Maintenance interval (Luminaire):
Maintenance interval (Lamp):
Failed lamps are replaced immediately:
Maintenance factor: medium (Room index 1.1 < k < 3.75) direct
B – Reflector open at the top
Metal Halide lamp (CIE)
CCG
3000 every 2 Years every 3.5 Years
Yes
0.61
Maintenance instructions:
Lamps must be replaced with suitable replacement lamps of the same characteristics (luminous flux, light color, color rendering). Any existing starters should also be replaced during relamping.
The room and surfaces deflecting light are to be maintained so as to preserve the original reflection characteristics.
Always comply with the manufacturer’s cleaning instructions.
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Measures to comply with a required minimum lighting level include regular cleaning of the room and the luminaire, as well as timely replacement of the lamps.
Timely replacement of the lamps also ensures avoidance, for the most part, of undesirable effects at the end of the lamp service life.
When compiling the maintenance plan, consideration must be given to the decrease in luminous flux over the course of the lamp service life in the form of the lamp luminous flux maintenance factor (LLMF).
The CIE has stated a general luminous flux curve for metal halide lamps which results in a maintenance factor of 0.68, for example, for 9000 h.
Given the lesser drop in luminous flux in POWERBALL
HCI ® over the service life compared to standard metal halide lamps with cylindrical tube, the maintenance factor for 9000 h is 0.8.
In practice, this results in the following application cases (see also table 2):
To achieve a constant luminous flux of min. 500 lx throughout the service life, taking cleaning and change intervals into account, the following applies initially:
• Standard lamp and lamp change after 3 years, i.e. for an LLMF of 0.68 (case 1):
962 lx approx. 17% higher illuminance, i.e. more luminaires
• POWERBALL HCI ® and lamp change after
3 years, i.e. for an LLMF of 0.8 (case 2):
820 lx
• Standard lamp and lamp change for an LLMF of
0.8, here after 14 months (case 3):
820 lx lamp change required after 14 months , as 80% of the initial lumens achieved after 3500 h.
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