Digital drives restore Royal Danish Theatre

May 5, 2009
As part of refurbishing The Royal Danish Theatre, intelligent drives from Sprint Electric, Arundel, England, were specified to extend the lives of the existing dc motors.

Located in the heart of Copenhagen, Denmark, the beautiful “Gamle Scene” — the old stage of The Royal Danish Theatre — was built in 1874. Last summer, the old stage’s machinery was upgraded and Visual Act, a Swedish company specializing in stage design and technology, installed a new control system. As part of the refurbishment, intelligent drives from Sprint Electric, Arundel, England, were specified to extend the lives of the existing dc motors.

By using nearly all of the original motors and most of the original mechanics, the upgrade was completed at a far reduced cost.
In addition to new control electronics for 36 motor-driven fly bar hoists, the project included: installing a stage control system with four portable control desks and redundant servers; upgrading six lighting bridges for increased lifting capacity; installing four new manually moveable point hoists; and a complete upgrade of the old revolving stage driven by dc motors.

For the old stage, new drives and electronics are installed to control the dc motors on the 36 fly bar winches. To monitor fly bar position, a new arrangement with an angular gear, absolute encoder, and limit switch is mounted on each winch. Two Profibus communication channels are provided, one for the drives and one for absolute encoders and safety I/O. Onboard software modules of Sprint Electric’s PLX drives facilitate the complex system and include a closed positioning loop.

The six existing lighting bridges are upgraded to increase their load capacity to 800 kg, with new motors, gearboxes, and brakes — as well as new electrical cabinets with servo amplifiers and electronics.

In order to increase safety, slack wire detection is added. In addition, angular gear arrangements similar to those used on the fly bars are installed for the light bridge encoders. During the refurbishment, the revolving stage was inspected and fitted with new encoders and a very old motor was removed to increase efficiency and reduce risk of fire.

The Visual Act control system is being installed in several other theatres throughout Scandinavia and is becoming a new standard in theatrical motion control. The system comes with two types of control desks: Advanced Desk includes a full keyboard and is ergonomically designed for work over longer periods, and Touring Desk uses a more compact touchscreen, suitable for operation from a variety of locations.

At the Royal Danish Theatre, two Touring Desks are rail mounted on one of the galleries. The control system operates all movements in the theatre through a combined Profibus and Ethernet network that allows communication to all devices in the system.

For more information, visit Sprint Electric.

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