Magnetic ballasts modulate electrical current at a relatively low cycle rate , which can cause a noticeable flicker. Magnetic ballasts may also vibrate at a low frequency. This is the source of the audible humming sound people associate with fluorescent lamps. Modern ballast designs use advanced electronics to more precisely regulate the current flowing through the electrical circuit. Since they use a higher cycle rate, you don't generally notice a flicker or humming noise coming from an electronic ballast.
Different lamps require specialized ballasts designed to maintain the specific voltage and current levels needed for varying tube designs. Fluorescent lamps come in all shapes and sizes, but they all work on the same basic principle: An electric current stimulates mercury atoms, which causes them to release ultraviolet photons.
These photons in turn stimulate a phosphor, which emits visible light photons. At the most basic level, that's all there is to it! To learn more about this remarkable technology, including descriptions of various lamp designs, check out the links below. Sign up for our Newsletter! Mobile Newsletter banner close. Using more sophisticated circuitry and components, ballasts can control the current running through fluorescent lights with greater precision.
Some older electronic ballasts employ the rapid-start method described above, while newer and more advanced models use what are known as instant-start and programmed-start. These ballasts were developed so lights could be turned on and operated at their brightest at the first flick of the switch. Rather than pre-heat the electrodes, the ballast uses a high-voltage boost around volts to heat and light the filaments and then the mercury gas.
Designed for areas in which the lights are constantly switched on and off, these ballasts pre-heat the electrodes with controlled amounts of current before applying a higher voltage to start the light.
When magnetic ballasts break, it is often blamed on the bulb. You can find out whether the issue is with the ballast, starter or the lamp with our guide - Easy Fixes for Slow to Start, Flickering or Faulty Fluorescent Tubes. In order to ensure that the issue is with the ballast, you will want to test it with a multimeter. A multimeter is designed to measure electric current, voltage and resistance. They are inexpensive and can be found at most electronics shop.
These instructions are for guidance purposes only — ensure you reference the manufacturers wiring diagrams. If you are missing the instruction manual, most major manufacturers will have opies on their website. If the ballast is not the problem, you may need to replace your fluorescent tube.
You can find out how to do this safely with the guide Replacing and Recycling Fluorescent Tubes Safely.
Cheaper ballasts are likely to need more rewiring than a fitting that has a branded ballast in it. The process for swapping out magnetic ballasts for electronic ballasts is pretty simple and straightforward. This is the direction the lighting industry is headed in, so why not swap them sooner rather than later to optimise your space with better, quieter lighting?
In newer lamps the process provided by a starter is built in, making the function of a separate starter redundant. If the lamp fixture does have a starter, it will be obvious. You should find a small grey cylinder plugged into the light fitting. High frequency control gear is a modern single ballast that performs the functions of all the different components in the standard switch start circuit. Lights which are operated with a high frequency ballast do not flicker, but instead light up instantly due to the frequency being much quicker.
These mix with the mercury gas and other gases that are in the lamp. When this happens, the electrons actually bump into atoms that are in the gas, releasing wavelengths of ultraviolet light that are consumed by the fluorescent coating on the inside of the lamp. This then ultimately produces the light we can see. The job of the fluorescent ballast is to manage this entire process by giving the lamp the voltage it needs to get the process done. At the same time it makes sure it doesn't take in so much that it burns out.
That is because a fluorescent lamp is inherently has a negative resistance, meaning it will just keep on taking in voltage until its power supply can't take anymore. To combat this, the ballast supplies the opposite resistance -- positive -- to restrict the current.
In its simplest form, a ballast uses magnetic energy that erupts into the lamp when it is turned on, stimulating the electrodes to make a current and the lamp glows. Today's fluorescent ballasts are mainly electronic, and they have a number of positive attributes including energy efficiency, reduced flicker of light, and even dimming capabilities. There are a also a few different types of fluorescent ballasts to know about.
One of the more popular types of ballasts is the instant-start ballast. Rather than warming up the lamp's electrodes gradually, the ballast a rather large initial voltage to get it going. Although this helps save energy since there's less energy used when compared to other ballast types, the lamp degrades quicker. We recommend this for fixtures that will not turn off and on all the time. A rapid start ballast works differently from an instant start as it does allow the lamp time to preheat by initially using a low voltage.
Without a ballast to limit its current, a fluorescent lamp connected directly to a high voltage power source would rapidly and uncontrollably increase its current draw. Within a second the lamp would overheat and burn out. During lamp starting, the ballast must briefly supply high voltage to establish an arc between the two lamp electrodes.
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