Effects of Daylight Harvesting on Electronic Lighting Control C opyright © 2004 Joshua Scot Lester - Calvin College Engineering 315 Control Systems

© 2004, Joshua S. Lester2 Triac Dimming Zero-crossing A dimmer controls the power to the load through a solid state switch or triac. The triac is synchronized to the AC line through signals obtained at zero crossings Triac-firing The zero crossing signals are then used to fire the triac to give the correct dimmed waveform

© 2004, Joshua S. Lester3 Daylight Harvesting System [10] Closed-Loop Lighting Control System Diagram

© 2004, Joshua S. Lester4 Photosensor vs. Photocell photocell the light sensitive component inside the photosensor. Photosensor an entire product including the housing, optics, electronics, and the photocell.

© 2004, Joshua S. Lester5 Spectral and Spatial Response [1] Closed-loop lighting control block diagram

© 2004, Joshua S. Lester6 Input characterization Spatial response The input to a photosensor is optical radiation  infrared (IR)  ultraviolet (UV) radiation For lighting control it is measuring the distribution of luminaire intensity [2] Photosensor Spatial Response Spectrum

© 2004, Joshua S. Lester7 Input characterization Spectral response sensitivity to optical radiation of different wavelengths [3] Spectral Response Chart [4] Optical Radiation Chart

© 2004, Joshua S. Lester8 Open-loop Proportional Control Open-loop control has one adjustable parameter the constant of proportion between the control voltage and the optical signal [5] Savings in the Spotlight [7] Open-loop control

© 2004, Joshua S. Lester9 Closed-loop Proportional Control 2 ADJUSTABLE PARAMETERS: 1. SLOPE ( open-loop response curve ) 2. OFFSET ( commissioning ) Closed-loop control algorithm a.k.a "sliding set point control" [5] Savings in the Spotlight[8] Closed-loop control

© 2004, Joshua S. Lester10 Control Algorithm Closed-loop proportional control The ceiling illuminance is 100 lux with no daylight present (from the 5:1 work-plane: ceiling ratio) Desired work-plane illuminance 500 lux Daylight enters the room and adds 250 lux Rate of dimming was set to -0.25% per lux 0.25% per lux X 250 lux = 62.5% This sets the luminaire light output to: 100 lux - (62.5% X 100 lux) = 37.5 lux. The total ceiling illuminance is now 37.5 lux lux = lux. [9] CL Example

© 2004, Joshua S. Lester11 Sample of Daylight Harvest Control [6] Simulation of lighting levels in modeled room.

© 2004, Joshua S. Lester12 Personal controls

© 2004, Joshua S. Lester13 Big Picture

© 2004, Joshua S. Lester14 References I. Rensselaer Polytechnic Institute, Troy, NY USA II. Rensselaer Polytechnic Institute, Troy, NY USA III. Rensselaer Polytechnic Institute, Troy, NY USA IV. Rensselaer Polytechnic Institute, Troy, NY USAhttp:// V.Savings in the Spotlight By John L. Fetters, published June ’02 VI. VII. Rensselaer Polytechnic Institute, Troy, NY USAhttp:// VIII. Rensselaer Polytechnic Institute, Troy, NY USAhttp:// IX. Rensselaer Polytechnic Institute, Troy, NY USAhttp:// X. Rensselaer Polytechnic Institute, Troy, NY USAhttp://