Have a 4 lamp t8/t12 fixture, had an old fluorescent ballast and t8 fluorescent tubes in it. there is a HP Laser color printer on the same circuit. When the printer is turned on (does not have to be printing) the lights flickered. We bypassed the ballast and installed LED tubes that we have used in all of our buildings. We still get the flicker. checked all connections, switch, tombstones, and outlet and found nothing. put a PQM on circuit and found nothing unusual with printer on or off. Still flickers but only with printer powered up. Also tried putting printer on a power conditioner with no success. Any Ideas?
led and fluorescent flickering
- Thread starter stardust
- Start date
- Status
kwired
Electron manager
- Location
- NE Nebraska
Laser printers/copiers have a heating element that cycles as needed to maintain temperature. Even in standby mode they are maintaining that temperature so the machine is ready to go on demand, though the cycling will be less then while printing. You are most likely experiencing some voltage drop whenever the heater is on. Your PQM should have caught this if connected to the load end of the circuit that the printer is connected to. If you connected it to the panel there may not be any significant VD there.
Your best solution is to probably put the copier on a different circuit from the lights if the flickering is too noticeable.
Thanks so much, If I have to I will run another circuit to the room.
Electric-Light
Senior Member
Laser printer should go on its own circuit. Not together with computers. Toner is powdered plastic and it has to be melted onto paper. Older printers kept the fuser warm all the time but in an effort to conserve energy newer printers tend to use higher power heaters that heat up quickly so it doesn't have to keep warm all the time. Control circuit drives it in a series of short rapid bursts and cause voltage drops faster than ballasts are designed to handle. Load regulation in many drop-in LED ballasts are an order of a magnitude worse than modern T8 fluorescent ballasts.
- Location
- Massachusetts
Are we supposed to take your entirely biased view as gospel or can you prove it?
Electric-Light
Senior Member
http://apps1.eere.energy.gov/buildings/publications/pdfs/ssl/flicker_fact-sheet.pdf
Unfortunately, there's no gospel. Voluntary industry standards didn't start off requiring flicker performance alongside lm/W and CRI requirements.
LED elements do not follow ohm's law and have an exponential curve. So, a 0.1% variation in output voltage causes far more than 0.1% fluctuation in power. Furthermore, the phosphor blend used for SSFLs don't have as much of an after glow as UV excited fluorescent lamp phosphor blends.
Extremely expensive show room LED products are well regulated like a computer power supply. The output of many LED products look like a deep pleated filter. The depth determines the flicker percentage. you can subjectively test it like the demonstration in that report. A highly flickery LED products produce distinct multiple images. Less flickery ones look more gradual and blurry.
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