DMX Contactor Power Racks

Type: Design and Commissioning of custom power rack cabinets

Our Solutions

Given the advances in LED technology and the impressive fixtures now manufactured by ETC and Martin, we are now being involved in theatre lighting design without the need for traditional dimmers. This is especially true in the Cruise ship market where we are often limited by power and the need to reduce the amount of heat generated by equipment.

On one project we were contracted to design custom contactor racks to fulfill the needs of the project as although the ETC Sensor rack is a marvelous piece of engineering when filling it with just relays it becomes an expensive solution.

The distribution rack needed to offer double pole isolation on every outgoing circuit, each circuit needed to be individually controlled via DMX, some circuits were to provide fixture power and needed to be controlled via a main key switch with the ability to individually reset channels, some circuits would provide non-dim power controlled from the lighting desk. These requirements were not the challenge – the real issue is that of ‘inrush’ currents. When a LED lantern is switched on there is an instantaneous high input current drawn by the power supply which arises as the capacitors are charged. On its own a single item does not cause an issue, however when a large quantity of fixtures are switched on this can be a problem. With the ever-increasing use of LED and moving lights especially with some of the cheaper products, we are increasingly getting calls about this issue.

Although we could have built a custom PLC module the client wanted an off the shelf solution so replacements were easy to come by around the world. After researching all the DMX controlled relay modules on the market we opted for the SCMR1232 unit manufactured by Eaton. This is a 12-way module with a 32A relay on each channel running the iCan software by iLight. The standard feature of this unit is that if all channels are set to full the module performs a sequence start up procedure thus avoiding ‘inrush’ issues. All the units are linked together using the iCan bus offering a neat and simple solution.

We attended training with iLight to gain a full understanding of the software and hardware restrictions and setup the commissioning programs.

The cabinet designs were completed and working with a marine electrical company we oversaw the building, testing and programming of these units before they left the UK. We look forward to commissioning them on board and seeing them working in action.

Although these units were 72 channels we can design and build custom rack down to 12 channels, please contact us to discuss your requirements.