# MH to LED



## niteshift (Nov 21, 2007)

Out with the 400w mh's
in with the 150w led's


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## FrunkSlammer (Aug 31, 2013)

Awesome, 250W savings! That's better than a blackhawk powerhouse!

0.25kWhr x 24hrs x 365 x $0.10/kWhr = $219

Bean counters love that stuff!

And hopefully they die prematurely so you can make more money installing another one.


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## niteshift (Nov 21, 2007)

FrunkSlammer said:


> Awesome, 250W savings! That's better than a blackhawk powerhouse!
> 
> 0.25kWhr x 24hrs x 365 x $0.10/kWhr = $219
> 
> ...


Yeah, thats why they were replaced, the bean counters rule.
About 20 of the mh fixtures in the pressroom.
When they die prematurely, we're here to replace them.


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## LGLS (Nov 10, 2007)

Are there any issues with stroboscopic effect on moving machinery with LEDs?


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## niteshift (Nov 21, 2007)

IslandGuy said:


> Are there any issues with stroboscopic effect on moving machinery with LEDs?


Found this:

*White Light Generation – LEDs
*_The vast majority of LEDs use a similar principle but instead use a blue LED coated in a phosphor material to generate the white light. The advantage of LEDs as a light source is the pump wavelength is around the 470nm wavelength +/-20nm and therefore does not contain UVA, UVB or UVC wavelengths that are harmful._

_ LED drivers which do not provide line frequency output won't be synchronised so whatever stroboscopic effect exists will be much reduced whenever there are multiple lamps._

_I´ve also seen LED for machine-tool lamps for a while and I´m not aware of any stroboscopic effects of them. Granted that I´ve only seen the DC types so far.
Unless we use a very poor DC power source, I don´t think that the ripple of a good one could cause the mentioned light output modulation. If I recall the LED theory correctly, once the supply voltage reaches the right thresold to light emission, further voltage increases do not lead to signficant increases of light output (non-linear behaviour). If that´s (still) correct, even using a poor power source it´s possible to get a flicker-free solution with LED_

_"Thank you for your enquiry regarding stroboscopic effect on rotating machines caused certain by types of lighting. CFLs can cause stroboscopic effect when they are being operated with conventional magnetic type ballast however if the CFLs are being operated with electronic Hf (high frequency) ballast then there will be no stroboscopic effect as the HF ballast will operate the lamp at high frequency therefore the light from the lamp will be seen as a constant light source and there will be no lamp flicker and no strobscopic effect. It is not quite so clear cut with regard to LEDs it depends on the driver that is used to operate the LED not all LEDs produce a constant light output therefore there is no guarantee that there will be no stroboscopic effect from LED light sources.
The compact fluorescent lamp that retrofits into a standard bayonet cap lampholder will be fitted electronic ballast and therefore you will not have any stroboscopic effect problems with this lamp, therefore you should be okay using this lamp."
_http://www.linkedin.com/groups/Stroboscopic-effects-from-LED-CFL-3995029.S.98985150


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## Awg-Dawg (Jan 23, 2007)

niteshift said:


> Out with the 400w mh's
> in with the 150w led's


 Do you happen to know the cost difference between the two?


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## niteshift (Nov 21, 2007)

Awg-Dawg said:


> Do you happen to know the cost difference between the two?


About 15 bucks for the mh, and about 400 bucks for the led.


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## Electric_Light (Apr 6, 2010)

IslandGuy said:


> Are there any issues with stroboscopic effect on moving machinery with LEDs?


Yes, absolutely, but completely dependent on the driver. It can be as bad as an orange neon light (like a timing light! ) or none at all (like a battery powered incandescent lamp) 




niteshift said:


> Found this:
> 
> *White Light Generation – LEDs
> *_CFLs can cause stroboscopic effect when they are being operated with conventional magnetic type ballast however if the CFLs are being operated with electronic Hf (high frequency) ballast then there will be no stroboscopic effect as the HF ballast will operate the lamp at high frequency therefore the light from the lamp will be seen as a constant light source and there will be no lamp flicker and no strobscopic effect. It is not quite so clear cut with regard to LEDs it depends on the driver that is used to operate the LED not all LEDs produce a constant light output therefore there is no guarantee that there will be no stroboscopic effect from LED light sources.
> ...


This is only partly correct. Look up how amplitude modification works with AM radio.The Hf ballast outputs 20-70kHz, but this is the carrier wave. The 120Hz ripple will manifest as amplitude modulation. The extent to which it modulates is no specified in datasheets. Some ballasts are regulated good enough to have lower flicker than incandescent. Some are not so good. 

Some LED drivers do not use any filtration. (For example Lithonia brand Versi Lite flickers so bad that you can almost use it as a timing light) These are worse than magnetic fluorescent light in amount of flicker. This is because SSFL (solid state fluorescent lamp, like white LED) uses a phosphor with less after glow than a regular fluorescent lamp, so there's less gap filling.

Generally, externally ballasted fluorescent systems are far superior to driver-in-bulb type LEDs in output regulations.


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## niteshift (Nov 21, 2007)

Electric_Light said:


> Yes, absolutely, but completely dependent on the driver. It can be as bad as an orange neon light (like a timing light! ) or none at all (like a battery powered incandescent lamp)
> 
> 
> 
> ...




Fluorescents do have a noticeable flicker that gets worse with age of bulbs/ballast.
We have had 1 of these 150w led hi bay replacements for mh for about 2 months installed, it's brighter then the 400w mh, no flicker noticeable at this point. The rest are being changed now.
Time will tell.
These are from China.


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## Electric_Light (Apr 6, 2010)

niteshift said:


> [/color]
> 
> Fluorescents do have a noticeable flicker that gets worse with age of bulbs/ballast.


You must be referring to magnetic ballasts. They inherently have 120Hz flicker. 

http://www.electriciantalk.com/f8/w...-flickering-disappointing-lamp-quality-67399/

Electronic fluorescent ballast that is well designed have almost no 60Hz pass through. Fluorescent and LED are similar. Incandescent coasts through the pulsations through thermal mass of the filament. 


> We have had 1 of these 150w led hi bay replacements for mh for about 2 months installed, it's brighter then the 400w mh, no flicker noticeable at this point. The rest are being changed now.
> Time will tell.
> These are from China.


At a lower light level, our eyes are more responsive to higher color temp. You compared a worn out 4,000K MH to a new out of box 5,700 LED SSFL. 

Did you compare the shadow pattern? Is the LED comparably diffused and softened as the metal halide? You can increase the foot candle value of a metal halide too if you put the lamp in a parabolic reflector like the one used in a flash light. 

You've got to compare 4000K MH to 4000K LED, 5700K LED to 5500K MH. Similar level of diffusion and optics. It's worth looking at output after about 6,000 hours of use. Test should be done when it is hot. For a high bay, ambient of 120F near fixtures isn't uncommon.

If glare reducing diffuser is omitted, it should be omitted from MH too so that you have a common comparison. 

You won't match a 400W MH with a 150W LED. A 400W MH lose 40-50% output over its lifetime. The probe start type is on the higher end of lumen drop. 

The output of metal halide at 10,000 hours and LED at about 20,000 hour should match because LED claims twice the life. Both on a hot day, after they've been left on for hours for temperature to fully rise. The input power needs to compare system power.

Check out the non LED solution:
http://www.usa.lighting.philips.com/connect/tools_literature/downloads/p-6000.pdf


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## Lighting Retro (Aug 1, 2009)

Lunera has a MH replacement where you leave the ballast in place. I've heard good reviews, but not a fan of leaving the old ballast in place.


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## niteshift (Nov 21, 2007)

Both the mh and led's use the same globe/w disfuser.
Some of the mh's were newer then others, so comparing the led's to them was sketchy at best.
Now that they're all installed you do notice some blue light showing, then was evident with just the one.


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## Electric_Light (Apr 6, 2010)

niteshift said:


> Both the mh and led's use the same globe/w disfuser.
> Some of the mh's were newer then others, so comparing the led's to them was sketchy at best.
> Now that they're all installed you do notice some blue light showing, then was evident with just the one.


You would have to use a spectroradiometer or a specifically calibrated light meter to measure foot candles and during the hottest time of the day after the light has been operating all day. Measuring within a few minutes of energizing can unduly favor the LED. Not every LED product on the market are tested according to LM-79 and LM-80 procedures and it's a common gimmick for many claiming energy savings to simply use lumen value given in LED chip datasheet at 25*C and multiply by the quantity used. 

"seems brighter" can be related to the scotopic vision which is favorable at 5700K than 4000K, not inherent LED benefits.


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## Spark Master (Jul 3, 2012)

Do you need to bypass the ballast? or just screw it in ?


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