Halogen lamps, which appeared relatively recently, have found the widest application in almost all spheres of our life. Compact, economical and durable, they are used for high-quality lighting of houses, streets, for decorative illumination, and can even be found in car headlights. So what are halogen or, as they are often called, halogen lamps? How do they differ from conventional incandescent bulbs? Today we are going to find out, and at the same time learn how to use them correctly.
Principle of Operation
In fact, a halogen light source is the same incandescent bulb. It has a filament body – a spiral of tungsten, soldered into a bulb. The bulb, in turn, is filled with an inert gas. Under the action of an electric current, the coil heats up and begins to glow brightly.
But despite the apparent similarity, the halogen light source has several significant differences from the incandescent light bulb you are familiar with. If you know how an ordinary incandescent light bulb is made, and have looked carefully at the figure above, you have noticed these differences yourself.
What this gives:
- Longer life. This is one of the main features of a halogen light source. The coil in an ordinary light bulb, having a high operating temperature, gradually evaporates and eventually burns out. In a halogen bulb, the bromine or iodine vapor added to the bulb captures the evaporated tungsten atoms and returns them back to the coil. This seemingly “trifle” increased the life of the device up to 4,000 hours (when using soft start systems up to 8,000-12,000 hours).
- Increased light output. Adding halogens not only increased the service life, but also allowed to heat the coil to a higher temperature. This doubled the luminous efficiency of the halogen bulb as compared with a conventional incandescent bulb and amounted to 15-22 lm/W.
- Improved color rendering. Thanks to the increased temperature of the filament body, the halogen bulb has an exceptionally accurate color rendering and a continuous emission spectrum that matches that of normal sunlight. With halogen light, all colors of objects look natural and the eyes are not tired.
- Compactness. The use of quartz glass, which can withstand high temperatures, made the devices very compact. This is not only convenient in operation, but also requires less consumption of inert gas and halogens, which makes production somewhat cheaper. Small size of the bulb allows it to easily withstand high pressure, and as you know, the higher the pressure in the bulb, the slower the tungsten evaporates from the coil. This increases the life of the device.
Like conventional incandescent bulbs, halogen bulbs can operate both on alternating and direct current. As for dimming, it is possible but undesirable because the temperature of the filament body and bulb decreases as the brightness decreases. This worsens or stops the tungsten coil reduction work of the halogens altogether.
The Differences in Halogen Lamps
Depending on their purpose, halogen light sources can differ
- by design;
- by socket;
- according to supply voltage.
Construction And Type
Today, the industry produces halogen lamps in a variety of sizes and shapes. Capsule devices have a form of a compact capsule bulb, which in addition can be equipped with a reflector. Typically, these lamps are used in vehicles and in lighting technology (film and photography, projectors, etc.), but can also be used for spot lighting of living quarters or landscape design.
Linear fixtures have a strongly elongated bulb and resemble a tubular fluorescent lamp in miniature. Contacts for power connection in such light sources are located at the edges of the bulb. The main fields of application of linear lamps are theatrical, illumination, searchlights and decorative illumination spotlights. They are used for cinema and photography.
Since a halogen lamp heats up a lot, it is a strong source of infrared radiation. IRC-lamps, which appeared relatively recently, do not have this drawback. A special coating on the bulb lets visible light through, but reflects infrared radiation back to the bulb. This solution has several advantages. Firstly, IRC device does not strongly heat nearby objects. Secondly, and most importantly, due to the reduction of heat consumption lamp is about 45% more economical than its conventional halogen counterpart and has twice the service life.
IRC-lamps are available in various sizes and at first sight can look like ordinary ones. You can distinguish them from ordinary halogens by the marking IRC.
Infrared lamps, unlike IRCs, work exactly the other way around. A special coating transmits infrared radiation, but detains visible light. Such devices are much more effective than conventional and even ceramic heaters. They do not need time to warm up – they go to work immediately after turning on and just as quickly cool down.
The last type of halogen lamps – a device with an additional outer bulb. In appearance, such a product almost does not differ from an ordinary bulb: the same base, the same shape of the bulb. But if you look closely, instead of a tungsten spiral you can see a miniature halogen bulb. What is the additional bulb for? First, it prevents contact with the red-hot halogen lamp. This eliminates the possibility of severe burns upon contact and makes the device more fire-safe.
Secondly, the outer bulb protects the main bulb from dirt, which halogen lamps are very afraid of: the dirt heated to 250 degrees Celsius causes local overheating of the main bulb and as a consequence, the failure of the device. A familiar look makes it easy to replace an incandescent bulb with a halogen one without changing the appearance of the luminaire.
The type of socket with which the lamp is supplied with voltage depends on the purpose of the halogen, its size, design and the magnitude of the supply voltage. Low-voltage compact lamps usually have a GU 5.3, G4, GY 6.35 pin base. In order to prevent such a device from being inserted instead of a 220V or 110V lamp, the latter are fitted with a GU10 (lockable), G9 or G12 (large pin) socket.
Devices with an Edison base (E27 and E14) are used to replace conventional incandescent lamps. Almost all of them are equipped with an additional bulb. Linear halogens have an R7 socket, and those designed for installation in vehicles are usually available with a standard “automotive” H or HR base.
Halogen light sources come in several operating voltages. There are not many of them: 12, 24, 110 and 220 volts. The 24 and 12 volt bulbs are designed to work in autonomous equipment (flashlights, portable lights, etc.) and vehicles: cars, motorcycles, trains and airplanes. Devices with 110 V and 220 V are used for lighting stationary objects: apartments, industrial premises, parking lots, etc.
Nevertheless, 12-volt and 24-volt lamps are also successfully used for conventional fixed lighting in spotlights for suspended ceilings. To do this, all you have to do is to connect them to 110 or 220 V mains via a step-down transformer – electromagnetic or electronic.
Advantages And Disadvantages
The advantages of halogen light sources I have already talked about at the beginning of this article, but I will briefly repeat
- long service life;
- high luminous efficacy;
- continuous emission spectrum and excellent color rendering;
- versatility and ease of switching.
Disadvantages of halogen lamps are few, but they are there:
- very high temperature of the bulb (in single bulb devices);
- sensitivity even to short-term increase in supply voltage;;
- low-frequency noise when working with a dimmer;
- disposal separately from ordinary glass.