Electric-Light
Senior Member
LED lights are fairly common by now, yet there's plenty of misunderstanding about this technology. Not just by typical homeowners, but stuff published in resources generally seen as credible professional source.
https://www.reminetwork.com/articles/three-highlights-of-switching-to-led-fixtures/
"LEDs contain no delicate filament or bulb to break, and no ballast to fail due to shock or vibration." -Michael Schratz is the VP of marketing for Dialight.
This is completely wrong in this context.
http://www.facilitiesnet.com/lighti...Facilities-Management-Lighting-Feature--12236
"Although SSL doesn't generate heat as a byproduct of generating light, the drivers and ballasts do"
Just wrong.
https://facilities.uw.edu/blog/posts/2016/04/05/leading-way-led
The IMA’s racquetball and squash courts have 204 mercury-vapor light fixtures using 250 watts each, requiring heavy and unsustainable ballasts, warm-up and cool-down times of 5-10 minutes, and plenty of maintenance calls to maintenance electricians to replace burned-out bulbs. But now those headaches are gone, replaced with the ease and energy savings provided by LED upgrades.
.
.
.
"There are many reasons for this increase in lighting failures, including the age of campus fixtures, which are sometimes 10-20 years past their life expectancy, and the inability to find replacements for older failing fixtures."
Poorly presented testimonials are common. By their own admission, old fixtures well past their intended life expectancy has something to do with troublesome frequent failures rather than LED vs non-LED.
The dictionary definition of the word "ballast" is a pretty good description of what lighting ballasts do.
A lighting ballast is used to interconnect a lamp that can not self stabilize at all or operate with enough stability when powered directly from a electrical source. LEDs behave like a touchy valve that goes from trickle to flood abruptly. This graph from Cree datasheet shows the very sharp change in current with a slight voltage variation. Temperature also shifts the curve. Each LED has a personality and exact voltage that makes one LED draw one current level does not replicate closely with another.
Ballast is used even for very basic LED circuit. In AC circuit, you can use a coil, capacitor or resistor to moderate current through a device with temperamental response such as arc tubes. The resistor ahead of each LED string keeps them manageable and stable as temperature and voltage shift around. A magnetic ballast is just as effective for LEDs as it is for anything else and it would perform its duty if it is placed before the rectifier or the LED strings can be put back to back so it would alternate between strings each half cycle.
It is possible to operate LEDs without a ballast, but it is not a good idea. They will see a dramatic swing in output. A flashlight that uses 4 AA battery with a series resistor is resistively ballasted and the ballast loss can be 25-40%. It is common for the LED industry to call whatever user recognizable device that sits in between the utility power and LED as a driver or a power supply. This may include or not include ballast function.
LED tapes often use a voltage source that is like a standard "AC adapter" to provide DC 12v. However, the tape itself is setup like ladder rungs and each segment is separately ballasted with solid state circuits or resistor. The system efficacy is the power pulled from the receptacle minus whatever transitional losses seen before reaching the LED elements.
This kind of ballasting is common for indicator lamps and primitive LED flash lights, however it is generally unacceptable for lighting applications due to high ballasting loss.
A "12v DC power supply" is equivalent to a constant psi regulator. The flow is dictated by the load.
Another type of "LED power supply" is a constant current which behaves as a flow meter which responds to changing conditions in load and changes pressure (within its range of accommodation) to maintain the same flow.
A standard T8 electronic fluorescent ballast can drive 2, 3, 4 and sometimes 5' lamps. The ballast maintains very close to the same current level over a limited range of string length, or lamp element voltage. An LED ballast has a rectified output and the nomenclature is different, but treated exactly like a sign ballast. For example, 350mA 10-25v. This means that it's intended for 350mA string that operates somewhere in that range with some margin. Five LED elements in series has a 15 to 20v ish range and the driver will proactively change voltage to hold 350mA.
The easiest way to maintain the same amount of flow through the entire pipe system is to connect them in series as getting proper current sharing between multiple parallel strings require careful matching. Though each LED element (like each Xmas light string lamp) runs at single digit voltage, LED sign ballasts and those used inside luminaires run plenty of voltage.
150W 0.35A ballast runs 415v.
http://images.philips.com/is/conten..._US-150W_0.35A_425V_HCN_LEDHCNA0350C425FO.pdf
Cree LED light bulb ballast runs about 230v.
Other than known exceptions such as vintage look "LED filament" lamps, most LED lighting utilizes ballast.
A 4-pin CFL is to "ballast LED" as ordinary screw-in CFL is to "ballast bypass LED". The "ballast bypass" or integral-ballast LED seems to be favored by energy retrofit sales industry to justify the cost of installation service. There are multiple power connection methods for integral ballast LED lamps. Safety and compatibility concerns haven't settled down yet. Some apply line voltage across two pins on one end while the other socket end exists solely to hold the lamp in place. This creates service sale justification opportunity for energy retrofit service companies and make it easy to install. It leaves the danger with the user as 277v applied across a fluorescent lamp can produce enough blast to pop open the lamp.
The above is a what you might find inside a common consumer type lamp. The example above uses pcLED/SSFL. The board is made of 15 two-chip packages (each SSFL element made of two blue LEDs in series and shared package and fluorescent phosphor blend) running at about 90mA operate at about 90v (with 5v ripple.. plenty of flicker percentage). It has a MOV at the input to reduce surge induced LED ballast failure. It is something you should know as, because LED ballasts use the same technology as fluorescent electronic ballast in the parts that generally fail and they usually fail the same way. Some use glass outer bulb and since the circuit is usually UL Class I, it is considered unsafe to operate with a broken bulb which match them up to CFL for breakage vulnerability.
https://www.reminetwork.com/articles/three-highlights-of-switching-to-led-fixtures/
"LEDs contain no delicate filament or bulb to break, and no ballast to fail due to shock or vibration." -Michael Schratz is the VP of marketing for Dialight.
This is completely wrong in this context.
http://www.facilitiesnet.com/lighti...Facilities-Management-Lighting-Feature--12236
"Although SSL doesn't generate heat as a byproduct of generating light, the drivers and ballasts do"
Just wrong.
https://facilities.uw.edu/blog/posts/2016/04/05/leading-way-led
The IMA’s racquetball and squash courts have 204 mercury-vapor light fixtures using 250 watts each, requiring heavy and unsustainable ballasts, warm-up and cool-down times of 5-10 minutes, and plenty of maintenance calls to maintenance electricians to replace burned-out bulbs. But now those headaches are gone, replaced with the ease and energy savings provided by LED upgrades.
.
.
.
"There are many reasons for this increase in lighting failures, including the age of campus fixtures, which are sometimes 10-20 years past their life expectancy, and the inability to find replacements for older failing fixtures."
Poorly presented testimonials are common. By their own admission, old fixtures well past their intended life expectancy has something to do with troublesome frequent failures rather than LED vs non-LED.
The dictionary definition of the word "ballast" is a pretty good description of what lighting ballasts do.
A lighting ballast is used to interconnect a lamp that can not self stabilize at all or operate with enough stability when powered directly from a electrical source. LEDs behave like a touchy valve that goes from trickle to flood abruptly. This graph from Cree datasheet shows the very sharp change in current with a slight voltage variation. Temperature also shifts the curve. Each LED has a personality and exact voltage that makes one LED draw one current level does not replicate closely with another.
Ballast is used even for very basic LED circuit. In AC circuit, you can use a coil, capacitor or resistor to moderate current through a device with temperamental response such as arc tubes. The resistor ahead of each LED string keeps them manageable and stable as temperature and voltage shift around. A magnetic ballast is just as effective for LEDs as it is for anything else and it would perform its duty if it is placed before the rectifier or the LED strings can be put back to back so it would alternate between strings each half cycle.
It is possible to operate LEDs without a ballast, but it is not a good idea. They will see a dramatic swing in output. A flashlight that uses 4 AA battery with a series resistor is resistively ballasted and the ballast loss can be 25-40%. It is common for the LED industry to call whatever user recognizable device that sits in between the utility power and LED as a driver or a power supply. This may include or not include ballast function.
LED tapes often use a voltage source that is like a standard "AC adapter" to provide DC 12v. However, the tape itself is setup like ladder rungs and each segment is separately ballasted with solid state circuits or resistor. The system efficacy is the power pulled from the receptacle minus whatever transitional losses seen before reaching the LED elements.
This kind of ballasting is common for indicator lamps and primitive LED flash lights, however it is generally unacceptable for lighting applications due to high ballasting loss.
A "12v DC power supply" is equivalent to a constant psi regulator. The flow is dictated by the load.
Another type of "LED power supply" is a constant current which behaves as a flow meter which responds to changing conditions in load and changes pressure (within its range of accommodation) to maintain the same flow.
A standard T8 electronic fluorescent ballast can drive 2, 3, 4 and sometimes 5' lamps. The ballast maintains very close to the same current level over a limited range of string length, or lamp element voltage. An LED ballast has a rectified output and the nomenclature is different, but treated exactly like a sign ballast. For example, 350mA 10-25v. This means that it's intended for 350mA string that operates somewhere in that range with some margin. Five LED elements in series has a 15 to 20v ish range and the driver will proactively change voltage to hold 350mA.
The easiest way to maintain the same amount of flow through the entire pipe system is to connect them in series as getting proper current sharing between multiple parallel strings require careful matching. Though each LED element (like each Xmas light string lamp) runs at single digit voltage, LED sign ballasts and those used inside luminaires run plenty of voltage.
150W 0.35A ballast runs 415v.
http://images.philips.com/is/conten..._US-150W_0.35A_425V_HCN_LEDHCNA0350C425FO.pdf
Cree LED light bulb ballast runs about 230v.
Other than known exceptions such as vintage look "LED filament" lamps, most LED lighting utilizes ballast.
A 4-pin CFL is to "ballast LED" as ordinary screw-in CFL is to "ballast bypass LED". The "ballast bypass" or integral-ballast LED seems to be favored by energy retrofit sales industry to justify the cost of installation service. There are multiple power connection methods for integral ballast LED lamps. Safety and compatibility concerns haven't settled down yet. Some apply line voltage across two pins on one end while the other socket end exists solely to hold the lamp in place. This creates service sale justification opportunity for energy retrofit service companies and make it easy to install. It leaves the danger with the user as 277v applied across a fluorescent lamp can produce enough blast to pop open the lamp.
The above is a what you might find inside a common consumer type lamp. The example above uses pcLED/SSFL. The board is made of 15 two-chip packages (each SSFL element made of two blue LEDs in series and shared package and fluorescent phosphor blend) running at about 90mA operate at about 90v (with 5v ripple.. plenty of flicker percentage). It has a MOV at the input to reduce surge induced LED ballast failure. It is something you should know as, because LED ballasts use the same technology as fluorescent electronic ballast in the parts that generally fail and they usually fail the same way. Some use glass outer bulb and since the circuit is usually UL Class I, it is considered unsafe to operate with a broken bulb which match them up to CFL for breakage vulnerability.
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