Slide 1

CP Rectifier development – A tight squeeze.

CP Rectifier development – A tight squeeze.

Richard Brodribb, M. Brodribb Pty Ltd

www.brodribb.com.au

Slide 2

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

Slide 3

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.

Slide 4

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

Slide 11

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

Slide 12

DISCUSSIONDISCUSSION