Slide 1 CP Rectifier development – A tight squeeze. Richard Brodribb, M. Brodribb Pty Ltd

Slide 2 Design Brief Existing public building Replace original TR (installed 1978) Rectifier output to be controlled in 15 separate zones Constant current, voltage limited operation Total capacity 50V 920A Synchronous interruption TABLE WITH KIND PERMISSION OF AURECON

Slide 3 Typical rectifier configurations For high current output with individual zone control -2 common solutions:- Phase control thyristor system with 15 separate rectifiers. Modular switchmode system with software configurable rectifier modules. We chose the second option.

Slide 4 Switchmode rectification What is switchmode rectification? Elements of the switchmode rectifier Primary rectifier – turns mains ac to high voltage dc Switching devices – turns high voltage dc into high frequency ac Transformer – transforms and isolates ac Secondary rectifier - turns transformed ac to back to dc Filter – to smooth the output Control circuit – to control the output voltage and current.

Slide 5

Slide 6 So far – so good. 50V 920A total rating – OK Zonal control – OK Synchronous interruption – OK Indoor mounting, so IP 43 (1mm, water 15 degrees) – OK Indoor site allows Fan cooling – OK AC 3 phase supply – OK Rectifier 1900 H x 2400 L x 650D, mass 1100kg – to fit thru normal doorway and round a corner – Not OK

Slide 7 Paul – through this door

Slide 8 Solution – construct TR in sections Build 3 separate cabinets that can be handled thru door and wired together on site. Switchmode modules mount in magazines, could be removed for shipment, minimise site wiring. Prewire at factory and test complete system

Slide 9 Installation issues Some control interwiring still required – which required special wiring assemblies Location of DC output had to match existing cable trench Limited site access due to teaching activities

Slide 10 Operational issues Total capacity approx 46KW Efficiency >90%, but heat loss still 4.6KW Lack of ventilation in cavity – rectifiers ran thermally limited. Solved by room exhaust fans – and door louvers – Satisfactory operation. PHOTO WITH KIND PERMISSION OF CCE

Slide 11 CONCLUSION 15 channel 50V 920A rectifier was required to fit through doorway into space restricted site. Sectional cabinet design with modular switchmode system was chosen A 15 channel rectifier comprising 3 cabinets and 39 rectifiers was constructed and installed Installation and operational issues included existing cable spacings, access and cooling Rectifier operates satisfactorily

Slide 12 DISCUSSION