Neon junction for GTO wire, the yellow thing is rubber and houses the connection between 2 letters for a "1 HR PHOTO" sign.. there was also another burned connection on the last 2 letters "T, O" and I had to run new wire to them and remove the neon to do so then re install it
This is why I perfer the ceramic junctions! They can't burn up
I suspect it burnt up because the wires weren't twisted well
The transformer is 12KV 30mA
yeah i bet. I see as many LED signs with unlit sections as i do with fluorescent. Mainly the CVS Pharmacy stores. they have LED store signs and letters are always out. so much for the 20-year maintenance-free thing but it keeps you in business! that's another thing with LEDs and these long-life lamps: loss in maintenance jobs.
The LEDs themselves are long lasting because they aren't over driven, but the drivers fail often!
The fluorescent signs have bad ballasts sometimes, usually an EOL lamp or two takes it out, especially those 4-6 lamp T12/HO ones, the lamps are all in series so every 2-3 years one burns out making a dim section
I was actually wondering just yesterday if a standard 2-lamp F40T12 magnetic rapid start ballast would work on 120vDC? I've heard 120vDC is really dangerous, though.
I always thought those flashing, glittering LED open signs were cool but I like seeing neon on buildings too.
Yeah DC is a lot more dangerous than AC when comparing the same voltages since you will "stick" to a DC current if you get shocked by it whereas you'll get "thrown back" by an AC current. Of course that's not to say that AC voltage isn't dangerous. a high enough current and your heart will stop.
I hate LED christmas lights. they have that annoying eye-grabbing 60Hz flicker to them (just like older LED car tail lights) and they don't have that warm feeling that the incandescent ones have. And white LED christmas lights just aren't the same as clear incandescents, though i prefer the colored christmas lights. i think the clear ones are drab and boring anyways lol.
Easy to make a magnetic LED driver, but it will dissipate more power than the LED unit itself. You can make a LED driver that will last the life of the LED array, but the unit will be both a lot larger and will cost about 50 times the price of the $2 LED driver. For $100 you can make a LED driver with quality components, running then well within ratings and running them with adequate input mains protection to survive the same as a magnetic ballast. That all costs money, and is only used for things like street light units where they have to be able to survive a 5 year unconditional guarantee period exposed in the open to all that comes down the wiring including spikes and sags.
yeah i personally think LED lighting systems are too "fragile" for industrial and utility applications where the line voltage might be inconsistant and the environment might not be ideal. LEDs are fine for residential use.
For gas station canopies and car dealerships, LEDs are nice and bright but for street lights they're always dim. So i think utility companies are replacing their HPS lights with LEDs that are designed to replace lower wattage lights (like replacing a 400W HPS streetlight with a 250w HPS equivalent LED fixture.)
Ouch! Yeah, neon is getting harder to find here too. A lot of new stores have LEDs inside those light up letters instead of neon tubes. And exposed tube neon is really hard to find now.
IIRC, magnetic ballasts require AC to operate so on DC systems, they either had resistive ballasts these needed a polarity reverse switch cause the lamp would only wear one way, inverter ballasts (I'm not sure if the early ones used a electromechanical vibrator or were already solid state), or just used regular AC ballasts off a M/A set.
according to what Joe said I guess all fluorescent ballasts need some sort of artifical AC converter when used on DC. I never knew that though. I thought that any AC device worked on DC but DC didn't work on AC (like how LEDs are DC-designed, as they only light when the current flows in one direction so they need a driver that also converts the AC to DC for optimum performance.)
DC will destroy transformers, thats what happens when an 8ft slimline recifies the lamp causes the ballast to run current in one direction which overheats it
That's right! Transformers and ballasts rely on something called reactance to limit current. It's a sort of resistance created by the variation of current generated by AC, to make it simple. A rectifying lamp cuts this AC in half, so the reactance and reduced (but not entirely eliminated) and current rises. And then the ballast fries. Pure DC is even faster as Sean said because there's no variation of current at all to create reactance.
ahh so a rectifying lamp is very bad for it's ballast? In a choke too?
how do the poletop transformers work on AC though because I only ever see one wire entering the top, the high voltage line. And then the three low voltage 120V, neutral, and 120V lines come out.
Pole transformers have the HV winding connected at one end to the bushing, the other end is connected to the steel case, which is connected to the earthing wire running down the pole to complete the circuit for the HV side. Thus you only have one HV wire with earth return, saving copper/aluminium in the long wiring runs from the switching yard. Has a problem though if the earth wire is broken/stolen in that the output will tend to rise to the Hv 11kV voltage.
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The fluorescent signs have bad ballasts sometimes, usually an EOL lamp or two takes it out, especially those 4-6 lamp T12/HO ones, the lamps are all in series so every 2-3 years one burns out making a dim section
I always thought those flashing, glittering LED open signs were cool but I like seeing neon on buildings too.
I hate LED christmas lights. they have that annoying eye-grabbing 60Hz flicker to them (just like older LED car tail lights) and they don't have that warm feeling that the incandescent ones have. And white LED christmas lights just aren't the same as clear incandescents, though i prefer the colored christmas lights. i think the clear ones are drab and boring anyways lol.
For gas station canopies and car dealerships, LEDs are nice and bright but for street lights they're always dim. So i think utility companies are replacing their HPS lights with LEDs that are designed to replace lower wattage lights (like replacing a 400W HPS streetlight with a 250w HPS equivalent LED fixture.)
I got a weird LED retrofit lamp today, pics to come later.
IIRC, magnetic ballasts require AC to operate so on DC systems, they either had resistive ballasts these needed a polarity reverse switch cause the lamp would only wear one way, inverter ballasts (I'm not sure if the early ones used a electromechanical vibrator or were already solid state), or just used regular AC ballasts off a M/A set.
how do the poletop transformers work on AC though because I only ever see one wire entering the top, the high voltage line. And then the three low voltage 120V, neutral, and 120V lines come out.
Vince, nice to see you on EEVblog.