Medium Voltage Application Guide
Medium Voltage Application Guide
Medium Voltage Application Guide
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CONTENTS<br />
Contents<br />
1 Introduction ........................................................................................................................................................................... 4<br />
2 Motors ...................................................................................................................................................................................... 5<br />
2.1 Common types of industrial motors .................................................................................................................................................. 5<br />
Induction motors........................................................................................................................................................................................... 5<br />
Useful formulae .............................................................................................................................................................................................. 6<br />
Slip-ring motors ............................................................................................................................................................................................. 7<br />
Synchronous motors ................................................................................................................................................................................... 9<br />
2.2 Motor starting methods ......................................................................................................................................................................... 10<br />
Direct on-line starting .............................................................................................................................................................................. 10<br />
Primary resistance starting..................................................................................................................................................................... 11<br />
Auto-transformer starting ..................................................................................................................................................................... 13<br />
Star-Delta starting ...................................................................................................................................................................................... 15<br />
Soft starters ................................................................................................................................................................................................... 16<br />
Variable frequency drives (VFD) ....................................................................................................................................................... 17<br />
3 Soft Starters ........................................................................................................................................................................ 19<br />
3.1 What is a Soft Starter .............................................................................................................................................................................. 19<br />
Open loop soft start control ............................................................................................................................................................... 20<br />
Closed loop soft start control............................................................................................................................................................. 21<br />
3.2 Benefits ............................................................................................................................................................................................................ 22<br />
Electrical Benefits ....................................................................................................................................................................................... 22<br />
Mechanical Benefits ................................................................................................................................................................................... 22<br />
<strong>Application</strong> Benefits .................................................................................................................................................................................. 22<br />
3.3 Anatomy ......................................................................................................................................................................................................... 23<br />
Key components ........................................................................................................................................................................................ 23<br />
SCRs.................................................................................................................................................................................................................. 23<br />
Snubber circuits .......................................................................................................................................................................................... 24<br />
Heatsinks ........................................................................................................................................................................................................ 24<br />
Fans .................................................................................................................................................................................................................... 25<br />
Busbars ............................................................................................................................................................................................................ 25<br />
Current sensors .......................................................................................................................................................................................... 25<br />
PCBs.................................................................................................................................................................................................................. 25<br />
Housing ........................................................................................................................................................................................................... 25<br />
Common functionality and features ................................................................................................................................................ 26<br />
3.4 AuCom <strong>Medium</strong> <strong>Voltage</strong> Soft Starters .......................................................................................................................................... 29<br />
MVS Soft Starter ........................................................................................................................................................................................ 29<br />
MVX Soft Starter ....................................................................................................................................................................................... 34<br />
Soft starter communication options ................................................................................................................................................ 40<br />
Predictive Maintenance Module (PMM) ........................................................................................................................................ 42<br />
3.5 Selection <strong>Guide</strong>lines ................................................................................................................................................................................. 43<br />
Considerations ............................................................................................................................................................................................ 43<br />
Switchgear Requirements ...................................................................................................................................................................... 45<br />
AC53 Utilisation Codes ......................................................................................................................................................................... 52<br />
3.6 Calculations ................................................................................................................................................................................................... 54<br />
What is the minimum start current with a soft starter? ....................................................................................................... 54<br />
Calculating required start current for new or existing AC induction motor installations .................................. 54<br />
3.7 Special <strong>Application</strong>s .................................................................................................................................................................................. 59<br />
Forward/Reverse motor starting ....................................................................................................................................................... 59<br />
Multi-motor starting ................................................................................................................................................................................. 61<br />
AuCom multi-motor starting solution ............................................................................................................................................ 64<br />
Slip ring motor control ........................................................................................................................................................................... 66<br />
3.8 Common standards for MV soft starters and switchgear panels ..................................................................................... 68<br />
710-12280-00A <strong>Medium</strong> <strong>Voltage</strong> <strong>Application</strong> <strong>Guide</strong> Page 1
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