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Technical Details – Components for Incandescent Lamps Dimmer operation VS safety transformers can be controlled using progressively adjustable phase-cutting leading-edge dimmers for low-voltage halogen lamps. Reliability and service life VS safety transformers are designed for a long service life. Provided the specified maximum values for the winding temperature are complied with during operation, a service life of 10 years can be expected. Failure rate: < 0.025%/1,000 hrs Conductor Contacts Electrical installation Conductors Connections Primary conductor cross-section: min. 0.75 m², secondary conductor cross-section: min. 0.75 m² for 50 W output and a min. of 1 mm² for 100 W output Terminal screws: max. torque of 0.5 Nm must not be exceeded Parallel connection Parallel connection is admissible on the primary side, but is inadmissible on the secondary side Conductors for low-voltage halogen installations As the high temperatures associated with the operation of low-voltage halogen lamps place severe demands on lampholder conductors, a skilful combination of conductor and insulation is essential. Tin-plated copper conductors with silicone insulation are recommended for temperatures of up to 180 °C at the cable's conductor; nickel-plated copper cables with polytetrafluoroethylene (PTFE) sheathing are recommended for temperatures of up to 250 °C. Welded connections ensure the most effective heat discharge. Control measurements should be carried out if other connection types are used, e.g. crimping or plug connectors. To prevent the risk of additional heat generation, the maximum permissible current load must be observed when dimensioning the conductor cross-section. When using electromagnetic transformers, the conductor resistance causes a relatively large voltage drop. This drop in voltage is always associated with a reduction of luminous flux. For instance, an 11% drop in voltage will lead to a 30% drop in luminous flux. For this reason, care should be taken to ensure secondary conductors are kept as short as possible and conductor cross-sections are adequately dimensioned when wiring luminaires. Nevertheless, transformers should not be mounted too near the light source (> 25 cm clearance if possible) to prevent the heat generated by the lamp from raising the ambient temperature above the critical level for a transformer. As electronic converters operate at high frequencies, consideration must be taken of the skin effect, i.e. the displacement of the electrons from the middle of the conductor to its surface. As a result, the full cross-section of the conductor is no longer used, resistance increases and thus leads to a greater drop in voltage. In addition, AC resistance, which is caused by feed line inductance, can result in an even greater voltage drop. It is therefore recommended that lamp conductors be laid closely parallel or twisted together. Voltage losses (V) with a two-metre secondary conductor Working frequency Load Cross-section/Voltage drop W 0.75 mm² 1 mm² 1.5 mm² 50 Hz (electromagnetic transformers) 50 0,38 V 0.29 V 0.2 V any wiring layout 100 0.74 V 0.56 V 0.39 V 40 kHz (electronic converters) 50 1.4 V 1.25 V 1.2 V any wiring layout (loops) 100 3.3 V 3.1 V 3 V 40 kHz (electronic converters) 50 0.5 V 0.45 V 0.35 V wires twisted together or closely parallel 100 1.2 V 1 V 0.85 V 324

Technical Details – Components for Incandescent Lamps Conductors for installations with halogen lamps All conductors must be selected to suit the luminaire conditions (see table) in terms of material, crosssection and insulation. Testing these conductors under worst case conditions is essential as the commonly occurring high temperatures considerably reduce the conductivity of the conductor and hence its current-carrying capacity. Insulation Conductor Cross-section Mains voltage Max. temperature Material mm² V °C SI Cu tin-plated (Cu vz) 0.75 300 180 FEP Cu tin-plated (Cu vz) 0.75 300 180 PTFE Cu nickel-plated (Cu vn) 0.75 500 250 PTFE Cu nickel-plated (Cu vn) 1 500 250 PTFE Ni 1 500 250 PTFE Ni 1.5 500 250 1 2 3 Lampholders For low-voltage halogen lamps With the exception of B15d bases, the low-voltage sector is dominated by pin bases, which are fitted with a variety of different pin distances and diameters. Apart from classic lampholders that ensure both the electrical contact and the correct positioning of the lamp, connection elements are also available. These components are solely responsible for establishing electrical contact and are used in cases where, for instance, the regulations demand that the lamp be attached to its reflector (e.g. cold-light reflector lamps with GZ4 and GX5.3 bases). Extremely high temperatures are also generated when operating low-voltage halogen lamps as a result of the tungsten-halogen cycle and high lamp currents. In addition, the respective luminaires are often of very compact design, which leads to heat accumulation and thus to high internal temperatures. The materials the lampholder is made of thus play a vital role for the luminaire's operating safety and the lamp's service life. In addition to tried-and-tested materials – ceramics for casings and mica for covers – ever more frequent use is being made of highly heat-resistant plastics like LCP (liquid crystal polymer for e.g. G4, GU4, GX5.3, GU5.3 and GY6.35 lampholders) and PPS (polyphenylene sulphide for G4 lampholders). Plastic lampholders provide clear advantages: narrow dimensional tolerances, no material fractures, low weight and clip-attachment options. The type of contact also plays an important role. Conventional contacts are only attached to one side of the lamp pin. In contrast, additional contact points – known as multipoint contacts – lead to a reduction of current density at the point of transition from the lamp pins to the lampholder contact and with that to a decrease in temperature. These contacts provide the further advantage of ensuring superior heat dissipation from the lamp pins to the conductor. The temperature advantage of multipoint contacts in defined conditions (including welded-on conductors) can amount to as much as 100 °C. In extremely rare cases, due to the high internal pressure in the bulb, it is possible for the lamp to shatter. For reasons of fire prevention (high temperature of the glass bulb), the lamp's components must be prevented from falling out. Enclosed luminaires meet these requirements. Open luminaires, however, may only be operated using lamps with enclosed bulbs or low-pressure lamps. Lamps of this kind are suitably marked with pictograms on the lamp's packaging and in the lamp manufacturer's documentation. Lamps marked with pictogram No. 1 are suitable for use with open luminaires, whereas those marked with pictogram No. 2 may only be used in enclosed luminaires. Lampholders for low-voltage halogen lamps are equipped with mounted cables or with plug-type connectors. In addition to the various lampholders contained in the catalogue, further lampholder models with various cable lengths and of various qualities as well as lampholders with plug-connected cables can be made available on request. VS lampholders for the UL market and UL approved leads are available for all common lamp types. Further information can be found at www.unvlt.com. 4 5 6 7 8 9 10 325

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