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LED Dimming Standards: NEMA SSL7
by Lindsay Stefans, LC, LEED AP
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SSL LIGHT SOURCES OPEN FORUM WIDE AND VARIED
FORMS 2
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FREE FORM
FIXED FORM
There is a place for both 3
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SSL DIMMING OPEN FORUM WIDE AND VARIED
PROTOCOLS
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Simplicity‌..We have yet to reach there.
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Problems with leading edge dimming of LEDs No consistency…………..
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NEMA Standards Publication SSL 7A2012 Phase Cut Dimming for Solid State Lighting: Basic Compatibility Small step to improve LED dimming compatibility
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CONTROL GEAR INTEGRATED OR IN SEPARATE HOUSING An LED light engine can have integrated control gear, or control gear in a separate housing LED Light Engine LED module Control Gear
integrated control gear
LED Light Engine
Control Gear
cable
LED Module
control gear in separate housing
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Dimming Standardization Phase-cut dimming
NEMA SSL7 status: •
Good progress on majority of technical parameters, but finalization of SSL7 Part A is mostly delayed by: – Off-state current (leakage current) specification & Dimmer Points • Lack of consensus on off-state current is mainly caused by different views by lamps makers and dimmers makers on absolute value of off state current • Part A covers the minimum requirements for compatibility. • Part B covers minimum requirements for performance.
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This standard is forward-looking and is intended to be used to design and qualify dimmer and LLE products (including integral or remote control gear) for use with each other. It is not intended for use to determine compatibility with existing products or the installed base of LLE’s and phase cut dimmers.
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Compatible – Two components of a system, for example a dimmer and a light source, when combined, provide basic functionality as described in SSL 7A Conduction angle - In the case of a forward phase dimmer, conduction angle is the phase angle (180-0 degrees) measured from the point where conduction begins (>20% of instantaneous line voltage) to next zero cross location (beginning of the next half-cycle). Phase Cut Dimmer – A dimmer, for the purposes of this standard, is a control unit that produces a forward phase (leading edge) AC waveform. This dimmer output waveform is supplied to one or more LLEs. The conduction angle of the waveform is adjustable. 14
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Two types of phase-control dimmers exist: forward phase and reverse phase.
Amplitude
Conduction Angle
Zero crossing
Phase angle (⁰) 0
100
200
300
400
500
600
700
800
GENERIC WAVEFORM PRODUCED BY A FORWARD PHASE CONTROL (LEADING EDGE) DIMMER 15
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Amplitude
Conduction Angle
Phase angle 0
100
200
300
400
500
600
700
800
GENERIC WAVEFORM PRODUCED BY A REVERSE PHASE CONTROL (TRAILING EDGE) DIMMER 16
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SSL7 WAVEFORM SPECIFICATION Nominal RMS Voltage / Frequency
Rise time from 10%-90% Vpeak
100V / 50h
40us +/- 30%
120V / 60h
5us +- 30%
230V / 50h
30us +/- 30%
277V / 60h
3us +/- 30%
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Inrush current is caused by initially applying power to the LLE. This current can stress mechanical switch and semiconductor components inside the dimmer and shall be limited.
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Certified Lighting Subcomponent Database (CSD) Listed subcomponents have also been thirdparty certified per EPA’s requirements at www.energystar.gov/3rdpartycert (tested at an EPA-recognized laboratory and certified by an EPA-recognized certification body).
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Standards can ensure desirable characteristics of products and services such as •quality, •environmental friendliness •safety •reliability •efficiency •interchangeability at an economical cost.
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FREE FORM
Seamless Materiality
Spatial Freedom
Less Distinction between Light Source and Building Material
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FREE FORM OLED (organic light-emitting diode) is a light-emitting diode (LED) in which the emissive electroluminescent layer is a film of organic compound which emits light in response to an electric current.
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FIXED FORM
Focused Technology Improvements
Multiple Platforms: Single form factor
Replaceability
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FIXED FORM An LED light engine is the combination of an LED module and its associated electronic control gear (‘driver’).
LIGHT ENGINES 24
Custom Projects
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Whether using Free Form or Fixed Form Solid State Light Sources Basic Principles Don’t Change
Blur the line between Source and Architecture
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FORM FACTORS
YOUR FEEDBACK 26