what is dimming?...dim up: 0 to 100% occurs when the dim down: 100 to 0% 60 70 80 o utput (%) occurs...

1Confidential Confidential –– Do Not Do Not DistributeDistribute

What is Dimming?What is Dimming?

Project UpdateProject Update Daniel Marcus Kathryn SweateryN. NarendranEdward Bear

CONFIDENTIAL CONFIDENTIAL –– Do Not Do Not Distribute Distribute –– PRELIMINARYPRELIMINARY

Jean Paul Freyssinier

© 2012 Rensselaer Polytechnic Institute. All rights reserved.

2

Please Note…

• The information contained in this presentationThe information contained in this presentation is preliminary and still under investigation. Please do not circulate.

• Once the research is finalized, we will submit reports or documents and provide an electronic copy to you.

CONFIDENTIAL CONFIDENTIAL –– Do Not Do Not Distribute Distribute –– PRELIMINARYPRELIMINARY© 2012 Rensselaer Polytechnic Institute. All rights reserved.

Introduction 3

• No formal definition of dimming– Universally understood as the ability of a light source to– Universally understood as the ability of a light source to change in light output between fully on and a minimum value

– Incandescent lamps: dim to zero– Linear fluorescent lamps: could dim to 1%

• Dimming modes: continuous or step– Purpose of dimming: ambiance, energy savingsp g , gy g

• Objective: Identify parameters that create a precise definition of dimmingprecise definition of dimming


Background 4

• LRC research focused onEvaluating dimmers/lamps under NEMA SSL 6– Evaluating dimmers/lamps under NEMA SSL‐6

• Electrical characteristics• Dimming profileDimming profile• Flicker

– Conducting human factors research to understandConducting human factors research to understand consumer requirements


Literature review 5

• IES Lighting Handbook (2000) identifies the following issues with dimmingfollowing issues with dimming– Dimming is contextual: absolute light levels, color shiftshift• Conference room: reading vs. audiovisual presentation• Color shift may be desirable in hospitality applicationsColor shift may be desirable in hospitality applications

– May be desirable and expected from incandescent lamps– Not desirable from fluorescent lamps

– No flicker– No audible sound


Literature Review 6

Human Factors Photometric Electrical

Dimming Characteristics Identified in NEMA SSL-6

• Dimming profile• Dead travel

• Maximum light output

l h

• Inrush current• RMS current

• Monotonic dimming

• Audible noise

• Minimum light output

• Color shift

• Voltage ring up• Current ring up• Pop on phase angle

• Light level turn on compared to set light level

p p g• Turn on time• Turn off voltage• Current crest factor• Flicker • Current crest factor• Efficiency


Study FocusSelected Parameters to Define Dimming

7

Selected Parameters to Define Dimming

1. Minimum light levelg2. Dimming profile

2.1. Dimming curve2.1. Dimming curve2.2 Dead travel2.3 Monotonic dimming3 o oto c d g

3. Flicker4 Audible noise4. Audible noise5. Maximum light level


1. Minimum Light LevelExperimental Design

8

Experimental Design

• Reading task (1) lamp in LabViewead g as– “Please let me know when the light

level reaches the minimum acceptable level where you can still

( ) ppendant control

acceptable level where you can still search for names and numbers in the white pages.”

6 Subjects (2 female), age 22-31 (average age 26)

• Ambiance setting task– “Please let me know when the light

level reaches the minimum acceptable level that you would dim to make the room relaxing and

f t bl ”Task: white


comfortable.” pages


1. Minimum Light LevelResults

9

Results

20%

25%

Level

Visual Task: Min. Acceptable Light Level

25 lx

30 lx

35 lx

Lig

ht

Visual Task: Min. Acceptable Light Level

5%

10%

15%

elative Min. L

5 lx

10 lx

15 lx

20 lx

25 lx

bsol

ute

Min

. LL

evel

0%0 lx 50 lx 100 lx 150 lx 200 lx 250 lx

Re

Maximum Illuminance

Ambient: Min. Acceptable Light Level

0 lx0 lx 50 lx 100 lx 150 lx 200 lx 250 lx

Ab

Maximum Illuminance


10%

15%

20%

Min. Level


8 l10 lx12 lx14 lx16 lx18 lx

Min

. Lig

ht

evel

0%

5%

10%

0 lx 50 lx 100 lx 150 lx 200 lx 250 lx

Relative M

0 lx2 lx4 lx6 lx8 lx

0 lx 50 lx 100 lx 150 lx 200 lx 250 lx

Abs

olut

e Le


Maximum IlluminanceMaximum Illuminance

1. Minimum Light LevelCFL samples

10

CFL samples

80%90%100%

Outpu

t

40%50%60%70%80%

Max Light O Dimmer 1

Dimmer 2Dimmer 3

10%20%30%40%

ercent of M

Dimmer 3Dimmer 4Dimmer 5Di 6

0%0%

CFL A CFL B CFL C CFL D CFL E CFL F

Pe

Lamp

Dimmer 6

19 (53%) combinations dim below 50%13 (36%) combinations dim below 25%10 (28%) combinations dim below 10%


10 (28%) combinations dim below 10%

1. Minimum Light LevelLED samples

11

LED samples

80%90%100%

utpu

t

50%60%70%80%

Max Light O Dimmer 1

Dimmer 2Dimmer 3

10%20%30%40%

ercent of M

Dimmer 3Dimmer 4Dimmer 5

0%10%

LED A LED B LED C LED D LED E LED F

Pe

Lamp

Dimmer 6

p

22 (61%) combinations dim below 50%19 (53%) combinations dim below 25%17 (47%) combinations dim below 10%


17 (47%) combinations dim below 10%

2.1. Dimming CurveExperimental Design

12

Experimental Design

• Subjects were asked if (1) lamp in LabViewSubjects were asked if the light level of each presentation matched

(1) lamp in pendant

LabViewcontrol

their expectations of the light level (in

t) t t d b 6 Subjects (2 female)percent) as stated by the experimenter.

6 Subjects (2 female), age 22-31 (average age

26)


2.1. Dimming CurveResults

13

ResultsExperiments verified the square law curve for brightness perceptionperception (n=15)


2.1. Dimming CurveResults

14

5

Results

90

100Dimming Profiles for Subject Evaluation

Curve 1*Curve 2*Subjective Curve

Average Subject Ratings(n=15)

2345

70

80

90

erce

nt (%

)

Subjective Curve

1012

40

50

60

ve L

ight

Out

put,

Pe

Curve 1 Curve 2

Subj.Curve

‐4‐3‐2‐1

10

20

30

Rel

ativ

‐5‐4

0 10 20 30 40 50 60 70 80 90 1000

Dimmer Travel, Percent (%)

*Curves 1 and 2, while based upon the NEMA


pboundary curves, are notactually the NEMA curves

2.1. Dimming Curve 15

M d di i f 5 LED/di bi ti

100

Dimmer Travel vs. Light OutputLEDs on Dimmer 2

Power Law

Measured dimming curves of 5 LED/dimmer combinations

70

80

90

(%)

LED ALED BLED CLED DLED EIncandescent Lamp

50

60

d Li

ght O

utpu

t

20

30

40

Mea

sure

d

0 10 20 30 40 50 60 70 80 90 1000

10

User Perception (Dimmer Travel, %)


2.1. Dimming Curve 16

M d di i f 3 CFL/di bi ti

100

Dimmer Travel vs. Light OutputCFLs on Dimmer 1

Power Law

Measured dimming curves of 3 CFL/dimmer combinations

70

80

90

(%)

CFL ACFL DCFL EIncandescent Lamp

50

60

d Li

ght O

utpu

t

20

30

40

Mea

sure

d

0 10 20 30 40 50 60 70 80 90 1000

10

User Perception (Dimmer Travel, %)


2.1 Dead Travel 17

90

100

Dim Up: 0 to 100%Dim Down: 100 to 0%

Dead travel occurs when the

60

70

80

Out

put (

%)

occurs when the actuator of the dimmer changes

l hil th

30

40

50at

ive

Ligh

t Ovalue while the light output does not.

10

20

30

Rel

a

0 10 20 30 40 50 60 70 80 90 1000

Dimmer Travel (%)


2.1 Dead Travel 18

Dead Travel at Bottom of Dimming Profile

90

100• Dimming profiles with various levels of dead travel were

Dead Travel at Bottom of Dimming Profile

t (%

)60

70

80

|_________________|20%

|____________________________|30%

of dead travel were assessed by subjects.

ut, P

erce

nt

40

50 |_____|5%|_________|10%

• None• Top of Profile ig

ht O

utpu

20

30– 5%, 10%, 20%, 30%

• Middle of Profile• 5%, 10%, 20%, 30% R

elat

ive

Li

0 20 40 60 80 1000

10

Di T l P t (%)

5%, 10%, 20%, 30%

• Bottom of Profile– 10%, 20%, 30%


R


( )

2.1 Dead Travel 19

• Dimming profiles with various levels of dead travel wereof dead travel were assessed by subjects.

• None• Top of Profile Subject Dimmer

– 5%, 10%, 20%, 30%

• Middle of Profile• 5%, 10%, 20%, 30%5%, 10%, 20%, 30%

• Bottom of Profile– 10%, 20%, 30%


2.1 Dead TravelResults

20

Results"Did you notice dead travel in the dimming

profile?"

80%90%100%

es' (%)

profile?

40%50%60%70%

onding

'Ye

Top of ProfileMiddl f P fil

10%20%30%40%

ects Respo Middle of Profile

Bottom of Profile

0%5% 10% 20% 30%Su

bje

Percent Dead Travel


2.1 Dead TravelResults

21

Results

3

“How distracting was the dead travel?”Extremely Distracting

2

2.5

ating

Top of Profile

Middle of Profile

B f P fil

y g

Very Distracting

1

1.5

2

raction Ra Bottom of Profile Very Distracting

h

0.5

1

Distr Somewhat Distracting

05% 10% 20% 30%

Percent Dead Travel

Not at All Distracting


2.2 Monotonic Dimming 22

80

90

100

%)

Dim Up: 0 to 100%Dim Down: 100 to 0%

Clear tolerance levels are needed

50

60

70

ght O

utpu

t (%

for ‘non‐monotonic dimming’

20

30

40

Rel

ativ

e Li

g

0 10 20 30 40 50 60 70 80 90 1000

10

Dimmer Travel (%)


2.2 Monotonic Dimming 23

90

100Noticeable Change in Brightness

Square Law CurveNoticeable Brightness Difference, HighNoticeable Brightness Difference Low

Clear tolerance levels are needed

70

80

rcen

t (%

)

Noticeable Brightness Difference, LowHigh cubic trendlineLow cubic trendline

for ‘non‐monotonic dimming’

40

50

60

ight

Out

put,

Per

20

30

40

Rel

ativ

e L

0 20 40 60 80 1000

10



3. Flicker 24

• Detection and acceptability of stroboscopic effects (above 100 Hz) can now be modeledeffects (above 100 Hz) can now be modeled (Bullough et al. 2012)

• What’s needed• What’s needed:– A method to distinguish between high frequency and low frequency light output signalslow frequency light output signals

– A model to evaluate frequencies below 100 HzLi i ‘ bl ’ i bl fli k– Limits on ‘acceptable’ perceivable flicker


25

Rated Acceptability of Stroboscopic Effects: Was it acceptable?

25100% flicker

40%

60%

80%

100%

. lig

ht o

utpu

t

Effects: Was it acceptable?0%

20%

0 1 2 3 4 5 6

rel. time

rel.

54% flicker

100%

0%

20%

40%

60%

80%

0 1 2 3 4 5 6

rel.

light

out

put

rel. time

25% flicker

60%

80%

100%

ght o

utpu

t

0%

20%

40%

0 1 2 3 4 5 6

rel. time

rel.

lig

5% flicker

0%

20%

40%

60%

80%

100%

rel.

light

out

put

Bullough et al. (Bullough et al. (2012 in press)2012 in press)http://www.lrc.rpi.edu/programs/solidstate/assist/recommends/flicker.asp


0 1 2 3 4 5 6

rel. time


4. Audible Noise 26

• Specific methodology requiredNEMA SSL 6 uses dBA with no test procedure– NEMA SSL‐6 uses dBA with no test procedure requirements

• Methodology standards (examples):• Methodology standards (examples):– ISO 532:1975ISO 9296 1998– ISO 9296:1998

– ISO 7779:2010


5. Maximum Light Level 27

max(%) dim(max)AC

• A dimmer/lamp combination should have a light output within X% of the lamp’s output when operated without lamp s output when operated without a dimmer.

Maximum Light Output Relative to Lamp on 120VAC

70%

80%

90%

100%

tput (%

)

30%

40%

50%

60%

ve Light Out DIM 1

DIM 2

DIM 3

DIM 4

0%

10%

20%

LED A LED B LED C LED D LED E LED F

Relativ DIM 5

DIM 6


Lamp


Recommends Draft Definition of Dimming1. Minimum light level

28

g– 10% of maximum light level

2. Dimming profile– Within a defined tolerance of initial profile (Figure 1)– No more than 10% dead dimmer travel anywhere in dimming profile– Monotonic dimming, within a defined tolerance of inverse change in

intensity over a dimmer travel period < 10% of dimming profile (Figure 2)

200

225

Noticable Variation in Brightness

Noticable brighness change above curveSubject preferred dimming profileNoticable brightness change below curveHigh TrendlineLow Trendline

200

225

Noticable Variation in Brightness

Noticable brighness change above curveSubject preferred dimming profileNoticable brightness change below curveHigh TrendlineLow Trendline

100

125

150

175

olut

e Li

ght O

utpu

t (Lu

x)

100

125

150

175

solu

te L

ight

Out

put (

Lux)

Figu

re 1

Figu

re 2

0 10 20 30 40 50 60 70 80 90 1000

25

50

75 Abs

0 10 20 30 40 50 60 70 80 90 100

0

25

50

75 Abs

F F


0 0 0 30 0 50 60 0 80 90 00Percent Dimmer Travel (%) Percent Dimmer Travel (%)

Recommends Draft Definition of Dimming 29

3. Flicker– No flicker below 100 Hz; < 25% flicker above 100 Hz.

4. Audible Noise– Maximum limit to be determined for audible noise; update methodology.

5. Maximum light levelN l th 90% f i h t d– No less than 90% of maximum when operated on constant AC voltage


Acknowledgments 30

FAA


U.S. EPA

31

Questions/DiscussionQuestions/Discussion


what is dimming?...dim up: 0 to 100% occurs when the dim down: 100 to 0% 60 70 80 o utput (%) occurs...

Documents