Dim and Dimmer – A guide to dimming lights

There are a number of reasons why you would want to incorporate dimming lights into your home or business premises.  For a start they help to create the perfect ambiance, provide flexibility to any room and help you achieve the right lighting.  Dimming helps you create the right visual experience, but most importantly it helps to reduce electricity usage and maintains the life of your lamps/ballasts.  For example, dimming fluorescent lighting control in an office building instead of repeated switching helps to increase lamp life and gives employees much greater personal control to set preferred light levels for specific tasks or times of the day/year.

You can utilise lighting control strategies to significantly improve the performance of any building.  By simply designing room absence/presence detectors, daylight sensors and/or automated time-based controls with fluorescent dimming you can carefully control the lighting in an entire building and further reduce electricity usage.  This can result in not only saving energy, but also costs, especially in a large commercial building.  However, the dimming methodology required is always entirely dependent on the lamp or the ballast used.  The key dimming methods are detailed below and all of them can be easily achieved with KNX dimmers:

1. Mains dimming involves decreasing and increasing the voltage to the lamp and is the traditional form of dimming associated historically with a rotary dimmer.  A KNX universal dimmer performs this kind of dimming and is capable of sensing the type of load (trailing edge or leading edge).  It is now possible to mains dim some LED and CFL lamps, though it would always be recommended to use a proper dimming control method as below.

2. 0-10V is one of the earliest and simplest electronic lighting control systems; simply put, the control signal is a DC voltage that varies between zero and ten volts. The controlled lighting should scale its output so that at 10V, the controlled light should be at 100% of its potential output, and at 0V it should at 0% output (i.e. “Off”). Dimming devices may be designed to respond in various patterns to the intermediate voltages, giving output curves that are linear for: voltage output, actual light output, power output, or perceived light output. For dimmable Fluorescent lamps (where it operates instead at 1-10v, where 1v is minimum and 0v is off) the system is being replaced by DSI, which itself is in the process of being replaced by DALI. For more information see http://en.wikipedia.org/wiki/0-10v.

3. DSI – Digital Signal Interface is a protocol for lighting control in buildings (initially electrical ballasts). It was created in 1991 by Austrian company Tridonic ATCO and is based on Manchester-coded 8-bit protocol, data rate of 1200 baud, 1 start bit, 8 data bits (dimming value), 4 stop bits, and is the basis of the more sophisticated protocol Digital Addressable Lighting Interface (DALI). The technology uses a single byte to communicate the lighting level ( 0- 255 or 0×00-0xFF). DSI was the start of digital communication technology and was the precursor to DALI. For more information see http://en.wikipedia.org/wiki/Digital_Signal_Interface.

4. DALI – The Digital Addressable Lighting Interface is a digital protocol for lighting control in buildings, such as electrical ballasts and dimmers. DALI was established as a successor for the still market dominating 1-10v and an open standard rival to Digital Signal Interface (DSI), on which it is based. DALI is standardized in accordance with International Electrotechnical Commission IEC 60929, standard for fluorescent lamp ballasts. Each piece of operating equipment with a DALI interface can be communicated with over DALI individually. Using a bi-directional data exchange, a DALI controller can query and set the status of each light. As a standalone system, DALI can be operated with a maximum of 64 devices. Alternatively, DALI can be used as a subsystem via DALI gateways. For more information see http://en.wikipedia.org/wiki/Digital_Addressable_Lighting_Interface.

5. DMX – DMX512-A is an EIA-485 based communications protocol that is most commonly used for stage lighting control and effects. Developed by the Engineering Commission of USITT, the standard started in 1986, with subsequent revisions in 1990 leading to USITT DMX512/1990. In 1998 ESTA began a revision process to develop the standard as an ANSI standard, including a Public Review process. The revised standard, known officially as “Entertainment Technology – USITT DMX512–A – Asynchronous Serial Digital Data Transmission Standard for Controlling Lighting Equipment and Accessories”, was approved by ANSI in November 2004. This current standard is also known as “E1.11, USITT DMX512–A”, or just “DMX512-A”, and is maintained by ESTA. DMX512 was originally intended as a ‘lowest common denominator’ protocol for use between interfaces supporting proprietary protocols. However, it soon became the primary method for linking not only controllers and dimmers, but also more advanced fixtures and special effects devices such as fog machines and moving lights. DMX512 is unidirectional and does not include automatic error checking and correction, so it is not safe to use for applications involving life safety, such as controlling pyrotechnics or laser lighting display where audience or performer safety is involved. MIDI is sometimes used for this task. For more information see http://en.wikipedia.org/wiki/DMX_(lighting).

Tags: DALI, Energy Management, KNX, Lighting Control

This entry was posted on Wednesday, September 16th, 2009 at 6:39 pm and is filed under Ivory Egg, KNX. You can follow any responses to this entry through the RSS 2.0 feed. You can leave a response, or trackback from your own site.