Philips Lighting Interview Questions & Answers

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Philips Lighting Interview Questions

    1. Question 1. Why Is There A Phase Out Of Incandescent Light Bulbs?

      Answer :

      European governments and the lighting industry are all working cooperatively on preserving energy and reducing CO2 emissions. Significant savings can be made by switching to energy-efficient light bulbs. The lighting industry will ensure that adequate choices of alternative lighting solutions are available at a reasonable price.

    2. Question 2. What Happens If One Keeps Using Traditional Light Bulbs?

      Answer :

      You can continue using inefficient bulbs in your house hold: the new EU law only regulates sales from retailers, but we strongly recommend switching to energy-efficient solutions helps reduce energy consumption and CO2 emissions, while, depending on the wattage, you can save up to €100 over the lamp lifetime (in most cases the average lifetime is 8 years) just by replacing, for example, a 100-watt incandescent with a 20-watt compact fluorescent lamp.

    3. Question 3. What Are The Consequences For The Consumers Who Are Looking For New Light Bulbs?

      Answer :

      Depending on the retailer’s current range, Philips will recommend the replacement products. To guide the shopper to the possible alternatives, Philips will work with the retailer on appropriate shelf navigation and in-store information material. Consumers who seek new light bulbs will automatically be guided to energy saving lighting solutions.

    4. Question 4. What Will Philips Do With Regards To Packaging?

      Answer :

      The new EU law also affects the information provided on the packaging. Extensive product information will be provided on pack and this will be implemented by the industry by 2010 at the latest. In the future, the term “energy is saving” may only be used for products with energy efficiency class A. Furthermore the wattage of a lamp will be stated, the energy level and the light colour.

    5. Question 5. What Are The Advantages Of Using A Remote Phosphor Process Compared To Using Phosphor Coated Leds?

      Answer :

      The remote phosphor process offers:

      • Longer lifespan, as it reduces temperatures and slows down the rate at which the phosphor layer degenerates.
      • Increase system efficiency with reduced operating temperature of the system.
      • Better color stability with longer life of phosphorus.
      • Less glaring than phosphor coated LEDs.

      More consistent flux output and correlated color temperature for the products, since LEDs from various bins can be used to produce light with consistent characteristics using the remote phosphor process.

    6. Question 6. What Terms Describe The Different Forms Of Leds From (basic Electronics To Fully Functional Light Fixtures) That Are Available In The Market?

      Answer :

      Here are the various terminologies for developmental stages of LED in chronological order:

      • LED Die - A small block of light emitting semi-conducting material on which functional LED circuitry is fabricated.
      • LED Package - This includes an LED die or more than one LED die with an optical element and mechanical, thermal and electrical interface.
      • LED Module - This includes and LED package or an LED die, possibly with an optical element connected to a circuit board, and with thermal, mechanical and electrical interface that are intended to be connected to the load side of the driver.
      • LED Engine - This is an LED module or array of packages with the associated control gear / LED driver. It is the nearest equivalent to the lamp in conventional luminaries.

    7. Question 7. What Does Smd Mean?

      Answer :

      SMD means surface mounted diode. This is a better technology than the first generation DIP LEDs. The SMD type LEDs are mounted on an aluminum substrate and enveloped in an epoxy resin.

    8. Question 8. What Does The Phase Out Mean With Regard To Availability Of The Products?

      Answer :

      Philips will do everything possible to make the energy saving products available, which the market demands.

    9. Question 9. Will Philips Invest In Additional Production Capacity?

      Answer :

      Philips will invest in making energy saving products available to meet the consumer demand.

    10. Question 10. What Is Energy Saving Lamp?

      Answer :

      Compact fluorescent energy savers are up to five times more efficient than incandescent lamps; in other words, they need up to five times less energy to generate the same amount of light. Philips CFLs last at an average 8 times longer than incandescent lamps, so need less frequent replacement.

      In addition a range of halogen energy savers is available, in shapes like the traditional incandescent and special halogen types (e.g. GU10 cap). They save 30-50% energy whilst providing the same light quality as incandescent lamps and their lifetime is 2-3 times longer.

    11. Question 11. What Costs Can I Save With A Compact Fluorescent Lamp?

      Answer :

      Depending on the wattage, a consumer can save up to €100 over the lamp lifetime (in most cases the average lifetime is 8 years) just by replacing a 100-watt incandescent with a 20-watt compact fluorescent lamp.

    12. Question 12. What Are The Advantages Of Smd Over Dip Leds?

      Answer :

      The advantages of SMD over DIP LEDs are:

      • Smaller size
      • More lumen output
      • Better heat dissipation
      • Lower lumen depreciation
      • Longer life

    13. Question 13. What Are The Various Types Of Led Chip Packages Available In The Market?

      Answer :

      The basic types of chip LEDs are:

      • SMD (Surface mounted diode) is a standalone chip on a ceramic base that can be integrated into various packages for linear LED strips or down lights.
      • COB (chip on board) LED, which comes as a high powered chip in direct contact with a printed circuit board optimal thermal management.
      • MCCOBB (multiple chips on board) LEDs, which are multiple COB LEDs, integrated to form a single chip. This technology is used in LED bulbs and tubes.
      • MCCOBB (multiple chips and cups on board) packages, which are used for high bay fixtures and floodlights.

    14. Question 14. Why The Price Of Energy Saving Lamp Higher Is Compared To A Traditional Light Bulb?

      Answer :

      The price of energy-saving lamps is higher but you can easily earn back your money by saving on high energy costs. The purchase price of energy savers has traditionally been more expensive than traditional incandescent lamps because they are more complex to produce (for instance: compact fluorescent lamps have integrated electronics). But over its lifetime an energy saving lamp can save up to €100 e.g. by replacing a 100-watt incandescent with a 20-watt energy efficient light bulb.

    15. Question 15. What Are The Typical Types Of Led Modules Available In The Market?

      Answer :

      LED modules may be available in the following forms:

      • Prefabricated chip on board which can be used for specific applications by luminaries manufacturers who design the heat sink and mounting conditions.
      • Chip on board with an optical lens or diffuser as a prefabricated piece with or without integrated heat sink. That can be used by luminaries manufacturers to integrate into luminaries.
      • Retrofit lamps to replace older (halogen) technology. This comes with an integrated heat sink and standard lamp base that can fitted directly into existing luminaries with a standard lamp holder.
      • Prefabricated luminaries with an integrated LED light source and heat sink complete with luminaries housing that is available as a sealed piece. The driver may be integral in the housing or may be remote.

    16. Question 16. Which Developments In Leds Have Reduced The Number Of Components In A System?

      Answer :

      • The chip on board (COB) package enables mounting of the package directly onto a heat sink instead of relying on a LED board manufacturer.
      • In many designs the heat sink is designed to be a part of the luminaries housing design, which reduces the number of components in the system.
      • The development of more stable mains voltage AC LED drivers is leading to solutions that can reduce wiring requirements and overall dimming cost.

    17. Question 17. What Is The Energy Savers Light Quality?

      Answer :

      Consumer nowadays has a big choice to select the lamp of their preferred light effect. Philips energy saving lamps renders a light quality which very closely approximates that of incandescent lamps. The Colour Rendering Index (CRI) expresses the level to which colours a represented in its natural form i.e. as if lit by sunlight. An incandescent lamp has a CRI of 100; this also counts for halogen energy savers. Philips compact fluorescent lamps have a CRI value between 80-85. Previous generations of energy savers, as well as many present unbranded energy savers, render an unnatural light, giving for example a grayish “cold” light. If a colour rendering index above 80-85 is needed for specific applications, energy efficient halogen lamps (halogen energy savers) with a CRI of 100 are recommended.

      Philips energy saving lamps has evolved to the point where they now are almost match incandescent lamps in functionality. Compared to several years ago, they last longer, are smaller, more efficient, safer and less expensive.

    18. Question 18. Will There Be An Energy Saving Alternative Lamp For Every Luminaries? Which Energy Saver Should I Buy To Replace My Old Incandescent Lamp?

      Answer :

      Philips offers a wide variety on shapes and light effects so that you do not have to compromise any more. For every application at home we have the energy saving alternative, either in compact fluorescent or halogen technology and last but not least there is a wide variety of Ledino LED fixtures available.

    19. Question 19. To What Extent Are Energy Savers Useful For Creating Home Ambiance?

      Answer :

      Energy saving lighting solutions will help you to create the desired in home ambiance. Some energy savers are dimmable. The new halogen energy savers and an increasing number of compact energy savers can be dimmed using common domestic dimmer switches. Furthermore the latest generation of energy savers fit all luminaries. This allows you to change light bulbs without having to change luminaries as well. Finally, the latest generations of energy savers come in every shape and size you could desire.

    20. Question 20. Does Frequent Switching Reduce The Lifetime Of Energy Savers?

      Answer :

      A compact fluorescent lamps life is hardly affected by switching it on and off. The current standards for 'Energy Saving Recommended' accreditation requires over 3,000 switching cycles per 8,000 hours of tested life which is more than sufficient for normal domestic use. In environments where lamps are switched frequently and are burning for less than 1 hour on average, we recommend a halogen energy saver or a “heavy duty” Cfli (e.g. Cfli Long life). Especially in restrooms where the light is switched off again every few minutes, the use of a halogen energy saver is highly recommended.

    21. Question 21. Do Compact Fluorescent Lamps Use More Energy During Start Up?

      Answer :

      No, they do not consume extra energy on start up and run very efficiently immediately. There is no reason to keep an energy saver switched on for longer than a normal incandescent bulb.

    22. Question 22. What Kind Of Energy Saver Offers Philips For Outdoor Use?

      Answer :

      There is a special energy saving lamp for outdoor use, the Philips Exterieur. This lamp is specially made to deal with a wider range of ambient temperatures and longer burning times. Philips also offers an automatic energy saver with a light sensor, which automatically switches on at dusk and off at dawn.

    23. Question 23. Why Do Leds Require Power Supply/drivers?

      Answer :

      LEDs are low voltage devices. Therefore, they require a device / Power supply unit / driver, or integrated electronics that convert line voltage to low voltage in order to run the LEDs. Sometimes the driver has electronics that can interpret control signals to dim LEDs.

    24. Question 24. What Are The Different Types Of Led Power Supplies / Drivers?

      Answer :

      • LEDs are driven by constant current (350mA, 700mA or 1A) drivers or constant voltage (10V, 12V or 24V) drivers.
      • Constant current drivers fix the current of the system and vary the voltage depending on the load of the LED.
      • Constant voltage drivers require a fixed voltage, and the LED loads are added in parallel across the output of the driver until maximum output currents are reached.

    25. Question 25. What Sort Of Applications Are Constant Current Drivers Typically Used For?

      Answer :

      Constant current drivers are typically used in down lights where one, or a series, of luminaries is used per driver. These are connected in series.

    26. Question 26. What Sort Of Applications Are Constant Voltage Drivers Typically Used In?

      Answer :

      Constant voltage drivers are used in applications where the load is not known and the LED loads are connected in parallel, for example in coves and signage applications. These drivers are sometimes similar to the low voltage electronic and magnetic transformers used in halogen light fixtures (MR16 lamps). The type of LED driver suitable to run a LED product is stated by the LED manufacturer in the product specification.

    27. Question 27. How Do I Know Which Type Of Driver Is Required By An Led Product?

      Answer :

      The LED rating of a product is usually noted in milliamps, mA or volts, V. Products rated in mA can be used with a constant current driver, while those rated in volts can be run with a constant voltage driver. LEDs designed for constant current drivers cannot run with constant voltage drivers without damaging them.

    28. Question 28. What Is Vf?

      Answer :

      VF is the term used for the LEDs forward voltage. It is the voltage required to activate the LED and produce the output specified, assuming that it is drawing the recommended current.

    29. Question 29. What Influence Does Energy Saving Lamps Have On E.g. The Correct Functioning Of My Audio- Or Tv System?

      Answer :

      The Philips energy savers do not disturb any other electrical devices. This phenomenon is caused by electro-magnetic interference. High quality products like Philips Energy Savers comply to global norms and specifications, meaning they do not disturb electronic devices.

    30. Question 30. Can Energy Saving Lamps Be Used In Combination With Special Switches Like Movement Detectors?

      Answer :

      All recently sold compact fluorescent energy saving lamps makes use of electronics to operate the lamp. Special electronic switches (like dusk-to-dawn or movement detection) are not compatible with the electronics inside the lamp, causing damage to the lamp. To allow for a good combination we advise the use of sensor equipment with a relay (mechanical switch) or equipment with an additional built in resistor to protect the lamp. In other words: due to its complexity, asks your installer/lighting specialist for advice.

      The Philips EcoClassic30 products are highly recommended for these applications, they are fully compatible with these electronic switches.

    31. Question 31. What Is The Impact On The Environment?

      Answer :

      Today, 14% of the electricity used in Europe is spent on lighting. By switching to energy-efficient solutions we could save an equivalent of 38 tons of CO2, 156 million barrels of oil and 52 power plants.

    32. Question 32. What Is The Maximum Permissible Distance Between An Led Product And A Remote Driver?

      Answer :

      The maximum permissible distance is dependent on the LED load, the conductor size, and the driver used. There is little practical limit on the distance between the driver and LED if you are using a constant current driver because it increases the output voltage to overcome any volt drop caused by the cable length. The distance between the LED and the driver is more important for constant voltage drivers where there is a voltage drop due to the load and length of cable.

    33. Question 33. What Are The Advantages Of 24v Leds Over 12v Leds?

      Answer :

      LEDs driven by 24V drivers have longer permissible distances between light source and driver compared to 12V DC LEDs. 12V LEDs are usually suitable for applications where low light outputs are required. 24V LEDs offer products with higher outputs than 12V products.

    34. Question 34. But Isn't True That Energy Savers Can Also Have A Bad Influence On The Environment?

      Answer :

      Compact fluorescent lamps contain electronics and a small amount of mercury. But if you follow the correct electronic waste disposal procedure, proper recycling will ensure that the environment will not be harmed.

    35. Question 35. Why Do Compact Energy Saving Lamps Contain Small Amounts Of Mercury?

      Answer :

      They contain a very small amount of mercury in order to radiate light. No mercury is emitted from lamps at any time, they are safe with regard to human health and the environment. Besides fluorescent lamps, the other energy saving lamp technologies do not use mercury, for instance halogen energy savers.

    36. Question 36. What To Do With A Compact Fluorescent Lamp When It Burns Out (proper Disposal Procedure)?

      Answer :

      In Europe, all Cfi lamps have to be disposed as special waste (under EWC Code 20 01 21-fluorescent tubes and other mercury-containing waste). Furthermore, as part of its obligations under the EU’s WEEE Directive , the European lighting industry has set up a European-wide recycling infrastructure, capable of recycling mercury, as well as other metals, glass, etc. All Cfi lamps are provided with the crossed-out wheeled dustbin logo. This means that they should not be disposed of in household waste but should be brought back to the shop or to the local waste facilities to be recycled.

    37. Question 37. Is It True That Some Leds Can Be Directly Connected To The Mains Voltage Power?

      Answer :

      LEDs are inherently low voltage devices and require drivers. However, many LED products in the market come with built-in drivers and hence can be directly connected to the mains voltage.

    38. Question 38. What Precautions Are To Be Taken When Mounting Led Drivers?

      Answer :

      LED drivers need to be mounted in a ventilated space. Access to the driver needs to be provided for general maintenance purposes. The IP (ingress protection) rating of the driver needs to be considered before finalizing the mounting location of the driver (only those drivers designed for outdoor environments can be located outdoors). The distance between the driver and the light source needs to be taken into consideration in order to prevent voltage drop, which results in reduced output of the LEDs.

    39. Question 39. How Are Leds Dimmed?

      Answer :

      LEDs are dimmed either by Pulse Width Modulation PWM, or by Constant Current Reduction CCR. PWM dimming involves switching current at a high frequency from zero to the rated output current. CCR dimming: The lighting level required is proportional to the current flowing through the LED. Current flows through the LED continuously and is reduced or increased based on whether the LED is to be dimmed further or made brighter.

    40. Question 40. What Are The Relative Advantages Of Pwm Dimming?

      Answer :

      Following are the advantages of PWM dimming:

      • Smooth dimming capability
      • More precise output levels
      • Better consistency in color over various levels

    41. Question 41. What To Do In Case A Lamp Breaks (proper Clean Up)?

      Answer :

      Since compact fluorescent energy saving lamps are made of glass tubing and can break if dropped or roughly handled, care should be taken when removing the lamp from its packaging, installing or replacing it.

      Breaking a lamp is extremely unlikely to have any impact on your health. Proper cleanup and adequate ventilation minimizes the impact even further. If a lamp breaks, ventilate the room for 20-30 minutes, remove the parts – preferably with gloves – and put them in a closed plastic bag in the disposal bin. Do not use a vacuum cleaner so that the remaining parts will not stay in the filter.

    42. Question 42. How Dangerous Is It When A Compact Fluorescent Lamp Brakes?

      Answer :

      Breaking a lamp is unlikely to have any impact on your health. The effects of the exposure to mercury from a broken energy saver to the human body are so to speak not measurable. Only if several lamps would break every day, and you would be exposed to all of the mercury, there could be a health concern that needs to be assessed. A Cfi contains less than 5mg mercury per lamp. By comparison, a typical thermometer, which we used to use, has between 500 and 3.000 milligrams of mercury, depending on its size. It would take 100 fluorescent lamps to equal that amount.

    43. Question 43. What Is The Status With Leds, I.e. Can They Already Be Used As An Energy Saving Alternative To Inefficient Domestic Lamps?

      Answer :

      LED technology is currently being used in some specific professional applications and offers great potential for the future of lighting.  For the consumer, Philips is offering LED fixtures Ledino, Livingcolors and several LED based home lighting accessories. In September 2009 Philips will launch its first range of LED retrofit lamps for the consumer channel.

    44. Question 44. What Are The Disadvantages Of Pwm (pulse Width Modulation) Dimming?

      Answer :

      Following are the disadvantages of PWM dimming:

      • Relatively more expensive.
      • Flicker perceived in peripheral vision if the driver is run below 100Hz frequency.
      • Stroboscopic effect evident in fast moving environments when the driver frequency is low.
      • Electromagnetic Interference (EMI) issues due to rise and fall of the current in PWM dimming.
      • Performance issues arise when the driver is mounted remotely from the light source.

    45. Question 45. In Which Applications Is Ccr (constant Current Reduction) Dimming Most Suitable?

      Answer :

      CCR dimming is good in:

      • Outdoor applications and damp locations.
      • Places that have strict EMI requirements like medical suites.
      • Places where there is a lot of motion and rotary machinery.
      • Applications where the drivers are to be placed at long distances from the light source.

    46. Question 46. Can Mains Voltage Led Products Be Dimmed With Traditional Incandescent Dimmers?

      Answer :

      Although LED products are marked as compatible with traditional dimmers, there are various degrees to which LED products are compatible with incandescent dimmers. Compatibility needs to be checked and tested on a product by product basis for the following most common undesirable behaviors:

      • Reduced dimming range
      • Flickering of the lamp
      • Inconsistent performance based on the number and different types of LEDs connected to a single incandescent dimmer.

    47. Question 47. What Are The Advantages Of Dimming Leds?

      Answer :

      Dimming LEDs offer the following advantages:

      • Saves energy, because less energy is used for reduced output levels.
      • Extends life; the electronic components run cooler. This not only extends the life of LEDs but also increases the life of the phosphor coating that is used to produce white light.
      • Helps designers create ambient lighting presets to create mood settings.
      • Increases flexibility in usage of space. A brightly lit space for reading or an office space can turn into a presentation/conference area by dimming.
      • Increases productivity by enabling individual control of lights in order to reduce eye strain and fatigue, or to improve concentration.

    48. Question 48. What Are The Various Control Protocols That Can Be Used For Dimming Leds?

      Answer :

      LEDs are controlled directly by signals coming from the central dimmer. They can also be designed to interpret other protocols like 1-10V, DMX, Ethernet or ZigBee signals from the central dimming system. The manufacturers of LEDs will specify which of the various protocols their devices can understand.

    49. Question 49. What Is The Difference Between Analogue And Digital Dimming?

      Answer :

      Analogue dimming is usually referred to as 1 - 10v dimming. In this case, a dc voltage is sent to the driver, which dims the LEDs in response to the voltage. With digital dimming, the driver receives a digital signal which tells it how to respond. The advantage of digital dimming is that fixtures are addressable. You can also have many more different levels of light output when using digital dimming.

    50. Question 50. What Lighting Protocol Is Appropriate For An Application?

      Answer :

      For applications where single colors and white LEDs are used, analogue or PWM dimming protocols can be used to switch or dim LEDs. For intelligent controls like creating dynamic effects, tuning of white light etc, DMX or Ethernet protocols can be used. Digital dimming works better with large numbers of luminaries.

    51. Question 51. Why Do Some Leds Flicker When Dimmed Or Turned Off?

      Answer :

      This is usually due to incompatibility between the driver and the control system. When purchasing an LED product, it is important to use the correct driver type as specified by the manufacturer. It is also important to check that the LED is dimmable. Some retrofits are not.

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