Holophane's Prismatron saves energy for Schneider Electric

In line with Schneider Electric's commitment to protecting the environment, the company is making use of Holophane's new PrismatronTM system as part of an overall energy management strategy in the recent extension to its Warehouse and Distribution Centre at Telford. The innovative PrismatronTM system uses prismatic glass high bay luminaires and special electronic dimming ballasts to provide dimming of 350W and 400W metal halide lamps in response to daylight levels and occupancy.

Transparent Building Technology

The Schneider Electric Global Competence Centre for Transparent Building technology (web-based building management systems) is among the key activities that are housed in the company's new purpose-built 10,000m2 extension to its existing Telford premises, which was officially opened in June 2003. The building also provides warehousing facilities, an assembly area for control panels and office accommodation.

These activities relate to all of the company's major brands - Merlin Gerin, Telemecanique and Square D - and to Sarel, a division of Schneider Electric. The premises will also be used as a reference site for potential customers wishing to examine the possibilities provided by Transparent Building technology in a live, practical situation.

The Telford extension is the latest phase in Schneider Electric's ongoing programme of investment in the UK and the whole complex is equipped with the company's Transparent Building systems, which represent the very latest in web-based building management technology. The diversity of operations on the site is such that no single energy management strategy would have been satisfactory. With Transparent Building technology, however, it has been possible to implement separate highly efficient energy management regimes for the office, existing warehouse and assembly areas, new warehouse, and low-voltage assembly areas.

Linking up to daylight

A key element of the design of the new building is the inclusion of a large area of skylights to allow natural daylight into the space. To achieve optimum performance of the lighting, therefore, it was desirable to provide dimming of the lighting. However, until Holophane's development of PrismatronTM this was not possible with higher wattage metal halide light sources.

"We opted for PrismatronTM because it enables us to make energy savings by using dimmable lighting in areas that are not used very often and at times of day when the lighting does not need to be at full output," explained Schneider Electrics Mike Biggs. The warehouse area is divided into four quadrants for the purposes of lighting control, with a lux sensor in each quadrant, used to maintain an illuminance of 280-300 lux. The assembly area for control panels is divided into two sections, each with a lux sensor, maintaining illuminance levels at 400 lux. "Each of the lux sensors produces a 0-10V control signal in direct proportion to the lux levels, sending the signal to a Schneider PLC building controller, which in turn communicates with the PrismatronTM dimmable ballasts," Mike Biggs continued. "In this way, the lamps are dimmed or ramped up in direct relation to the lighting requirements of the space."

Integration between the PrismatronTM system and the Schneider Electric BMS was carried out by Sietel. "The interface was supplied by Holophane and uses a very simple arrangement to control the lamps in relation to inputs from sensors," explained Sietel's Rory Bostock. "The BMS also provides a link between the lighting and the security system, so that the lighting is switched off when the security alarms are set and comes back on when the alarm systems are deactivated. In the event of a fault on the alarm system, the lighting is switched on," he added.

In the aisles between racking, occupancy detectors are also used in conjunction with the dimming system, reducing the lamps to 25% of their full output when no presence has been detected in the area for 10 minutes. As soon as someone walks into the aisle the lamps are increased to 100% output immediately. Again, this control is achieved through the Schneider Electric building controller.

With conventional on/off switching of metal halide lamps this rapid response to changes in daylight levels or occupancy would not be possible because of the warm-up time required by high intensity discharge lamps. As PrismatronTM dims the lamps, rather than switching them off, they are able to change the light output within seconds of receiving the appropriate control signal.

Fast installation, reduced project time

The system, installed by Kendall Electricical Services (Telford) Ltd on a design and build basis, uses 138 PrismatronTM luminaires connected in pairs to PrismatronTM remote dimmable ballasts. The luminaires are suspended directly from a Schneider Electric Canalis busbar carrying 230V mains power and integral low voltage control signals.

"Light levels in the warehouse area are set to 280-300 lux in the aisles and 400 lux in the low voltage assembly area," recalled Kendall's Bruce Gregory. "The fittings were very easy to install, hanging directly from proprietary clips direct from the bus bar. Connections between the ballasts and the control wiring use RJ45 connectors, while the light fittings themselves connect to the 230V mains supply with a plug and socket connection. These features made a significant contribution to the duration of the project and enabled us to install the lighting and associated controls in just three weeks," he added.

Light sources

At the Schneider Electric facility the PrismatronTM system is used with GE 350W and 400W metal halide lamps. "These lamps offer significant advantages over conventional metal halide lamps," explained GE's Eddie Guest. "They offer higher efficiencies, better lumen maintenance and improved colour rendering with a CRI (colour rendering index) of over 90. They also have improved colour stability, with a more consistent colour appearance from lamp to lamp, throughout the life of the lamps," he continued.

Minimising cost of ownership

In combining the PrismatronTM dimmable system with high efficiency ceramic metal halide lamps and its own leading-edge control systems, Schneider Electric has been able to create an advanced facility with minimal environmental impact and low cost of ownership. Reduced energy consumption is combined with extended lamp life, resulting in longer re-lamping cycles and lower maintenance costs.

About Prismatron

Holophane's Prismatron™system is a technological breakthrough with a fully controllable remote electronic ballast and prismatic glass high bay luminaire combination. The system is designed specifically for 320W, 350W and 400W metal halide lamps and was developed as a direct request from large end users, especially retailers where energy consumption is becoming a key issue when planning new store designs and refurbishment roll-out programmes.

The Prismatron™ system is kind to the lamp providing a less aggressive start-up to the arc tube prolonging lamp life and reducing ballast energy consumption. The operating characteristics of the PrismatronÔ system also enable the lamp to generate up to 15% more mean lumens than a conventional lamp after 8,000 hours duty. This offers a significant saving in luminaire quantities when a maintained illuminance calculation is used as well as the added advantage of extending lamp life.



January 2007