There are two types of ballast: iron-core (also known as reactive or magnetic ballast) and electronic.
Iron-core ballasts are inexpensive, have long lives, and are fairly tough. Iron-core ballasts may have an ignitor, used to start a discharge lamp, and a capacitor. The ballast, together with the ignitor and capacitor if installed, form the control gear.
Electronic ballasts are usually more energy efficient and flexible than iron-core ones. The electronic control gear comes as an integrated unit, usually known as an electronic ballast. Electronic control gear can only be used with lights which have wattages at or under 150W high pressure sodium; for anything higher than this you should use Active Reactor technology.
 - 80W MV Iron Core Ballast
 - T5 Fluorescent Electronic Ballast
The table below summarises the characteristics of the two ballast types. Ballast characteristic | Iron core | Electronic | “Toughness” | Tough | More likely to fail from a spike. Installing MOVs reduces this issue significantly (eg. T5 has 3 MOVs installed and CFLs have 2) | Degree of protection offered to the lamp | Low to high, depending on the degree of additional electronics | High. An electronic ballast shields the lamp from both over and under voltages | Ballast life | Up to 50 years. I.e. life of the fitting. | A 5.5% failure rate over 12 years operating at a typical temperature of 600C. Life increases with a lower temperature. | Lamp life | Lamp life is usually rated on an iron core ballast | Increases lamp life by up to 50 per cent because of the protection the ballast offers the lamp | Lamp failure mode | HPS lamp failure can damage the ballast, fluorescents can flicker on and off. | Ballast protects itself by switching off the lamps which are near failure. | Range of lamp wattages | All | Up to 150 watts available in Australia | Range of lamp types | All | All | IP protection required for reliable performance | IP 34 or 43 typical | IP 54 plus, preferably IP65 | Ballast energy consumption | High | Significantly less. Eg. 80W MV iron ballast uses 15.8 W, 2x14W T5 uses 2.5W. | Extra cost of adding “smarts” | High | Low in high volumes – extra features can be added to the ballast at relatively low cost – e.g. an addressable ballast. | Cost (distributor cost) | Low, approximately $3 for a twin fluoro lamp | High, approximately $40-$60 for a fluoro lamp |
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Mercury vapour and high pressure sodium lamps have different sets of control gear, as illustrated below. A high pressure sodium lamp has an ignitor and capacitor for power factor correction in addition to a reactive ballast, whereas a mercury vapour lamp does not.
 - Control gear for a 50W HPS lamp
 - Control gear for a 80W mercury vapour lamp
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Active Reactor is an electronically controlled magnetic ballast. It can control the power to all higher wattage HID metal halide, high pressure sodium and mercury vapour lamps in the power range 150W-2000W.
Unlike conventional lamps, which are susceptible to disturbances in voltage supply, lamp ageing and temperature variations, the Active Reactor device uses feedback in its operation and control mechanism to compensate for these factors. As such, it is largely immune to lamp disturbances. This ensures light output is more constant during the life of the lamp.
Running a lamp under these controlled conditions results in power and energy savings of around 17.5% of the energy over the life of the luminaire for a standard metal halide fitting and 22.5% for standard high pressure sodium lamps. The units are expensive (around $240 on top of the luminaire cost in February 2008) but lamp changeover costs will be reduced, as the lamp life should usually be around a third again the life of a standard metal halide or at least half again for the high pressure sodium lamps.
The Active Reactor consists of an electronic control unit including a single chip microprocessor which operates and controls a HID lamp in a programmed manner. It uses a microchip to electronically control a standard magnetic ballast for the starting and operation of lamps. Active Reactor technology has applications in both major road lighting and floodlighting.
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The energy consumption of floodlights can be reduced by installing Active Reactor devices. Further reductions can be achieved by replacing old mercury vapour, incandescent and halogen lights with metal halide fittings in combination with Active Reactors. Other options for controlling floodlights include timers, PE cells and motion sensors (with fast start lamp types).
LaTrobe City Council, Victoria, 2008.
A large scale trial of Active Reactor technology will commence in the LaTrobe Valley in March 2008. The trial, involving 500 lights in Morwell, Yallourn and Traralgon, uses 150 watt, 250 watt and 400 watt high pressure sodium lamps fitted in new streetlighting luminaires. The trial, which will run for at least four years, will provide statistically significant results with respect to energy savings, lamp life extension, lumen depreciation and operation of the Active Reactor electronics in the field.
The stakeholders involved in the project are the Active Reactor Company, the Centre for Energy and Greenhouse Technologies, Sylvania Lighting Australasia, the Latrobe City Council, VicRoads and energy distributor SP Ausnet. The project has been financed by the Victorian Government’s Sustainability Fund. For more information, see the media release prepared by the Victorian Minister for the Environment or visit the Active Reactor website.
City of Melbourne, Victoria, 2007
The City of Melbourne will conduct a trial of Active Reactor technology to determine energy savings and the feasibility of installing it on a broad scale across the municipality.
The trial will commence early in the 2007–08 financial year and will involve replacing the current metal halide luminaires in Collins Street (approx 100) with new luminaires, 50 of which will contain the Active Reactor and 50 will not. The new luminaires will be metered to determine the reduction in electricity consumption between the test lights and the control lights.
City of Whitehorse and the Active Reactor Company, Victoria, 2004
The City of Whitehorse and the Active Reactor Company retrofitted 12 X 250W high pressure sodium lamps and luminaires in Springvale Road. Monitoring of the trial, part of the former Sustainable Energy Authority Victoria's 2004 Sustainable Public Lighting Initiative (SPLI), was undertaken to determine the effectiveness and power saving potential of this new technology.
A more detailed description of the trial and results can be accessed via the Active Reactor website.
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The Active Reactor Company
For further information on the Active Reactor and/or the Springvale Road trials, contact Dr Richard Dluzniak, Director, The Active Reactor Company, Ph: +61 (0)3 9817 6677.
Sylvania Lighting Australasia
Sylvania Lighting distributes the Active Reactor product in Australia.
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