Ballasts are an important component for lamps, yet their role and significance is frequently misunderstood. A ballast is a device that regulates how much electricity a light bulb receives. Too little power and the bulb won’t light up. Too much power and you risk blowing a bulb. Not all ballasts are created equal. There are two types of ballasts available; magnetic and digital.
Magnetic ballasts can be more affordable, durable and tolerant of a wide range of temperatures. However they are heavy, inefficient, have no built-in protection, and aren’t controllable or dimmable. They also generate a lot of heat.
Digital Ballasts are highly efficient, safe and adaptable while being dimmable and able to work with a controller. They also produce less heat, are lighter and smaller than magnetic ballasts, and often have built-in protection and safety features.
Digital ballasts use switching electronics and small frequency inductors to control current and voltage to the lamp. They contain a ‘microprocessor’ similar to what’s used in a home computer. This allows digital ballasts to run both M.H and HPS lamps, make adjustments based on the type of lamp, and even compensate for degrading lamps by increasing output!
The higher frequency excites the lamp's gas within the arc tube to run at a much higher frequency. Old style magnetic ballasts cycle at 50 times/sec (hertz), so is effectively like strobe lighting that can be seen through a digital camera. Digital ballasts cycle at 28,860 times/sec (hertz), providing non-flickering constant light that has a large impact on yield. Light output is also increased through constant distribution, lamp efficiency and increased lumen output. Lamps will also stay brighter for longer giving them an increased lifespan. This is particularly true for metal halides that are very sensitive to the voltage supplied to the lamp.
Digital Ballasts are much more power efficient than magnetic ballasts (they use 1/3 less power).
Digital Ballasts are fitted with 'soft start' technology and have very low start up currents (amps). This is a huge advantage for growers using multiple ballasts, allowinmg more ballasts to be turned on at one time on a single circuit or timer. Most timers have 10 - 15amp contacts and can usually only handle 2 x 600w magnetic ballasts (4.8 amps each) at a time before the contacts go and you will find your timers don’t turn on or off, or you blow a circuit fuse.
The following data shows the extremely high start up currents and running watts on standard new magnetic core and coil ballasts within Australia. Brands A and B are some of the most widely used ballasts in the country. Older ballasts have an even higher start up current and wattage use, making them even more inefficient.
This data shows why so many customers blow their timer contacts and mains fuses when igniting 2 x 600w lights at the same time. In contrast, digital ballasts can be ignited at up to 4 lights at a time off a single 10amp fuse or timer!
In addition, when connecting large numbers of digital ballasts, you can turn on (or stagger) many more lights, more frequently because they reach full output within approximately 2 minutes (rather than 20 minutes like magnetic ballasts).
Digital Ballasts generate 20% more lumens that penetrate down 30-50% Deeper meaning up to 20-25% yield Increase - BUT using a third less power !!