Large Hollow Shaft Encoder Helps Save The Planet

A large bore hollow shaft absolute encoder has been designed by Thistle Design to assist in an experimental solar power project being operated by Sandia National Laboratories in Albuquerque, New Mexico. The project involves manipulating the sun’s rays using an array of two hundred heliostats and focusing them on a power tower target. This has proved very successful and further developments are anticipated.

In these days of increasing concern over fossil fuel based methods of power production it is heartening to hear of large scale initiatives to harness environmentally friendly energy sources.

One such initiative being carried out at the Sandia National Laboratories is assisting in the development of solar energy driven power stations. Their national solar thermal test facility has an array of over two hundred heliostats focusing the sun’s rays on a target at the top of a 200 feet (60 metre) high tower.

The solar power collected by the heliostats is of order 5 Megawatts and could in theory generate 1 Megawatt of electricity. Experimental data gathered has been used to assist in the design of a 10 Megawatt plant in California.

Last year Sandia contacted Thistle Design to see if we could supply a 16 bit absolute encoder which would improve the performance and reliability of their heliostats. The encoder had to be designed to fit into the existing space envelope and have the same output code format as the previous version. It would also have to fit over a 7.24 inch (184mm) diameter shaft.

A period of discussion followed as engineers at Thistle Design and their Sandia counterparts tried to fully define the requirement and select the best technical solution to the problem. The optimised design resulted in the type 200HSA-102 encoder and a prototype unit was installed for evaluation purposes in 2006 and has been operating successfully since then.