Download - Slide 1 CP Rectifier development – A tight squeeze. Richard Brodribb, M. Brodribb Pty Ltd
Slide 1
CP Rectifier development – A tight squeeze.
CP Rectifier development – A tight squeeze.
Richard Brodribb, M. Brodribb Pty Ltd
www.brodribb.com.au
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Design BriefDesign Brief
Existing public buildingReplace original TR (installed 1978)Rectifier output to be controlled in 15 separate
zonesConstant current, voltage limited operationTotal capacity 50V 920A Synchronous interruption
TABLE WITH KIND PERMISSION OF AURECON
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Typical rectifier configurations
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.
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Switchmode rectificationSwitchmode rectification
What is “switchmode” rectification? Elements of the switchmode rectifier
Primary rectifier – turns mains ac to high voltage dcSwitching devices – turns high voltage dc into high frequency
acTransformer – transforms and isolates acSecondary rectifier - turns transformed ac to back to dcFilter – to smooth the outputControl circuit – to control the output voltage and current.
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So far – so good.So far – so good.
50V 920A total rating – OKZonal control – OKSynchronous interruption – OKIndoor mounting, so IP 43 (1mm, water 15 degrees) –
OKIndoor site allows Fan cooling – OKAC 3 phase supply – OKRectifier 1900 H x 2400 L x 650D, mass 1100kg – to fit
thru normal doorway and round a corner – Not OK
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Paul – through this doorPaul – through this door
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Solution – construct TR in sections
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
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Installation issuesInstallation issuesSome control interwiring still required –
which required special wiring assembliesLocation of DC output had to match
existing cable trenchLimited site access due to teaching
activities
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Operational issuesOperational 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
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CONCLUSIONCONCLUSION
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
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DISCUSSIONDISCUSSION