Sharpedge Engineering Limited Client Portfolio:

Strand Lighting

Strand Lighing home page About Strand Lighting

Strand Lighting is the leading manufacturer of lighting, dimming and control systems for theatrical, television and architectural applications. The Strand name is synonymous with the best in lighting innovation, quality and professionalism.

(This section was paraphrased from the Strand Lighting website)

Project Information

We were involved with Strand Lighting from April 1993 until May 1994, working on the design of a range of stage lighting control systems.

We had full responsibility for all aspects of the hardware development, from initial specification, through to detailed design and prototype development, and liason with the factory for the manufacture of pre-production units. Two related products were designed. The first was for the European market, whilst the other was for the United States. They were based upon a common core, but with significant differences to cater for regional preferences.

Twin processor modules based upon the Siemens SAB80C166 micro-controller, controlled up to 250kW of lighting from a variety of control sources. The product was designed to satisfy different market requirements in various countries. High performance and high reliability were required, since the market is largely feature driven, but low production costs were vital, since existing products were too expensive to manufacture. The chosen micro-controller had the right mix of performance and on-chip peripherals to make possible a highly integrated product that was feature-rich and competitive. Apart from the power electronics, the product used surface mounted technology throughout to achieve very high component densities and high reliability. EMC was an important issue, with differing requirements for different countries. The product was designed for automatic manufacture.

The completed control system comprised a rack about 2m high, containing 72 or 96 dimmer modules, 2 processor modules and a contractor's wiring section. Each dimmer circuit contained an SGS Thomson ST6 micro-controller which monitored the state of the dimmer and the bulb, periodically reporting to the processor modules. The processors were arranged so that if either failed, the other would take over automatically. In the event of both processors failing, a set of panic switches allowed an operator to ensure that at least some lights were illuminated, albeit at full intensity, because the "show must go on".

An off-line 3-phase power supply provided the DC supply to the processor module. Zero crossing detector circuits provided a timing reference for the phase controlled dimming, while true rms monitoring of the mains potential allowed the lamp brightness to be corrected with a fluctuating mains supply. The combination of high voltage and low voltage circuitry meant that electrical safety was extremely important.

The software was stored in FLASH. A special sequence of front panel button presses put the processor module into a mode that allowed new software to be loaded from a remote PC, using the bootstrap loader firmware in the 80C166 processor.

The EC90-Supervisor and the CD80-Supervisor were successful products, especially the American version. They delivered ground-breaking performance with their dimmer monitoring capabilities, dual processor and panic button facilities, together with many novel software features, all at the right price.

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