MeerKAT Lightning Protection, Earthing and RFI Mitigation 01 December 2010 Dr. Gideon Wiid Post-Doctoral Fellow Host: Prof. Howard Reader.

Slides:

Advertisements

Similar presentations

Interface and cabling characterization for SKA Paul van der Merwe Prof. HC Reader Stellenbosch University.

Advertisements

Chapter 20 Reading Quiz Dr. Harold Williams.

Electricity & Magnetism. Universal Forces Throughout all galaxies far, far away……… Remember, FORCES exert a push or pull on objects and can do WORK They.

The study of electrical charges.  Two possible states of charge:  Positive and negative ▪ Named by Benjamin Franklin ▪ He decided what was considered.

WHAT IS SUPERCONDUCTIVITY?? For some materials, the resistivity vanishes at some low temperature: they become superconducting. Superconductivity is the.

10.3 Charges at Work: (Pages )

SMAW Equipment (Shielded Metal Arc Welding- commonly called “stick welding”, or “arc welding”)

Atomic Bonding Mr. Skirbst Physical Science Topic 15.

Electric Field Line Patterns Point charge The lines radiate equally in all directions For a positive source charge, the lines will radiate outward.

RFI Characterisation of Karoo Array Telescope Structure P. Gideon Wiid (PhD) Howard C. Reader Riana H. Geschke Stellenbosch University December 2008.

Lecture 4: Conductors Forces on charges and torques on dipoles.

Electricity How is it made?.

Electricity and Magnetism Physics 102 Professor Lee Carkner Lecture 8.

Electricity and Magnetism Physics 102 Professor Lee Carkner Lecture 9.

2. 2s /eo between, ±s /eo outside. 3. zero both between and outside.

Voltage and Electric Fields Sparks will fly. Going back to gravity for a moment Think about gravity a moment: Anything near the earth is pulled in by.

Electrostatics (Static Electricity)

Overvoltage Protection, A. Zeddam, Dakar, Senegal, 25 March 2015 ITU Regional Standardization Forum For Africa Dakar, Senegal, March 2015 Overview.

Electricity 3 rd Grade Science Electricity Everything in the world is made up of atoms. Each atom has smaller parts in it. One of those parts is called.

Electrical Fundamentals

Electricity and Magnetism ISCI Electricity is a Force – Vector – Electric charges (attract and repel) – Comb and Ball Example 2.Atoms – Protons.

Unit 3 Day 1: Voltage, Current, Resistance & Ohm’s Law Batteries Electric Current Conventional Current Resistance Resistors Energy Dissipated in a Resistor.

1 Faraday’s Law Chapter Ampere’s law Magnetic field is produced by time variation of electric field.

Electricity & Magnetism

Lightning Protection Chapter 6 PowerPoint slides by

Magnetism Opposite poles attract and likes repel

Electric fields. Objectives Interpret electric field diagrams. Describe and calculate the relationship between electric force and electric field for a.

ELECTRICITY l The purpose of an X-ray unit is to convert electric energy into: l ELECTROMAGNETIC ENERGY of the x-ray beam.

Electricity and Magnetism

Chapter 31 Faraday’s Law.

What is Electricity? Electricity is a form of energy that can easily be converted to other forms of energy.Electricity is a form of energy that can easily.

Electricity Chapter 13.

Investigating EMC policies for the SKA Paul van der Merwe Prof. HC Reader Stellenbosch University.

DateAssignment Mon TuesTextbook Page 399 #1,2,4 WedCalculating currents worksheet ThursTextbook page 405# 7, page 413 # 6 FriTextbook page 430 # 1,3,4,5.

8.022 (E&M) – Lecture 5 Topics:  More on conductors… and many demos!

Bits (0s and 1s) need to be transmitted from one host to another. Each bit is placed on the cable as an electrical signal or pulse. On copper cable the.

Faraday’s Law and Induction

RFI Mitigation for Electronic and Natural SKA Environment Philip Kibet Prof HC Reader Stellenbosch University SKA Postgraduate Bursary and Postdoctoral.

Hosted by Ms. Bristow Magnetism RHROpticsMisc

Electric fields. Objectives Interpret electric field diagrams. Describe and calculate the relationship between electric force and electric field for a.

SECTION 2-1 CONT. Bonding. TYPES OF CHEMICAL BONDS  Bonds involve the electrons in an atom.  1. Ionic Bonds Electrons are transferred from one atom.

Characterization of radiated sparking noise in the SKA environment Philip Kibet Prof HC Reader Stellenbosch University SKA Postgraduate Bursary and Postdoctoral.

Static Electricity. Definitions Conductor: Allows current to pass Insulator: Does not allow current to pass Point discharge: Charge concentrates at a.

Lecture A Fundamentals and Background. Charge “Charge” is the basic quantity in electrical circuit analysis Fundamental charge quantity is the charge.

Electricity Basics of electricity. Electricity Atoms – The smallest unit of each element Electrons – negatively charged particles in atoms Ions – charged.

CP Physics.  Space around every electric charge acts as a force field that will interact with other charges  Can only observe a field by watching the.

Prof R T KennedyEMC & COMPLIANCE ENGINEERING 1 EET 422 EMC & COMPLIANCE ENGINEERING.

L 29 Electricity and Magnetism [6]

Electric Charge (1) Evidence for electric charges is everywhere, e.g.

Electric Fields Montwood High School AP Physics C R. Casao.

 Electrical Insulator - a substance where electrons cannot move freely from atom to atom.  Electrical Conductor – a substance where electrons can move.

The line of force or Field line direction is the path a small positive test charge would follow if free to move Electric field patterns An electric field.

Unit 3 Electricity & Magnetism Magnetic Field, Currents & Plasmas Physics 5h Students know changing magnetic fields produce electric fields, thereby inducing.

Electricity and Magnetism. Atom Review Electrons have a negative charge (-) Protons have a positive charge (+)

Electricity Bingo!! It’s Electric (Boogy-Woogy). Words Amperes Chemical Conduction Conductor Contact Current Decreases Electric discharge Electric.

Electricity & Magnetism Chapter 7 Section 1 Electric Charge.

Electricity & Magnetism Standards

Static Electricity Created by Craig Smiley (Harrison HS, West Lafayette, IN) Supported by grant PHY from the National Science Foundation and by.

Force between Two Point Charges

Electric Charge.

General Outcome #1: Investigate technologies that transfer and control electricity.

Magnets & Magnetic Fields

Electricity and Magnetism Review

Charging without contact

Electric Charge Electric Charge Rules:

Principles of Electricity: Electric Charge and Force

Two charges, of equal magnitude but opposite sign, lie along a line as shown. What are the directions of the electric field at points A, B, C, and D?

Presentation transcript:

MeerKAT Lightning Protection, Earthing and RFI Mitigation 01 December 2010 Dr. Gideon Wiid Post-Doctoral Fellow Host: Prof. Howard Reader

Engineering Search: Nearby Galaxies and Pulsars Galaxy nearby: Cape Town Pulsar serviced, no more timing problems

Acknowledgements EM research group at SU: Prof. Howard Reader, Joely Andriambeloson, Dr. Braam Otto, Dr. Paul van der Merwe, Philip Kibet SKA SA Teams for support in measurements: Japie Ludick, Richard Lord, Carel van der Merwe, Luyanda Boyana, Siya Tshongweni NRF and SKA SA Sponsorship TESP funding for equipment

RFI Background Reverberation Chamber and cable transfer impedance Lightning Protection RFI Mitigation Earthing Menu

Contrary to popular belief: RFI ≠ Black magic NB: Electrons and Energy Opposite charges attract Electric field in between two polarities Electron experiences force in E-field Background to RFI ≠ RFI

Free electrons – sneaky little rascals Always takes the path of least resistance! Very Excitable – especially with time-varying E-field applied Electron E-field lines: stationary vs. moving Background – Electrons

Background – Making Waves

Joely Andriambeloson – Transfer impedance of cables Reverberation chamber – Stirring or mixing waves Characterise avg or max Confirm field uniformity Standard radiator Compare to calibrated data Compare to GTEM Future: OATS Reverberation Chamber

Cable transfer impedance vs shielding effectiveness 15 SKA cables and metal braided sheath GPS cable compromises Shielding chamber Influence on overall shielding effectiveness Cable Transfer Impedance

Elevation Motor assembly Lightning current levels Bonding efforts Path of least resistance Dirt road vs highway Traffic jam! Lightning Protection 1

Rogowski coil used for current measurement (pool noodle) Structure currents spread out LDC and Elevation currents concentrated Bearings grease changes impedance FEKO simulations currently busy Lightning Protection 2

Impedance: Z C = 1/jωC Z L = jωL ; HF Currents more concentrated Lightning Protection 3

Azimuth bearings Shoes and LDC conductor Misaligned 2 vs 4 FEKO during PhD Measurements Nov RFI Mitigation 1 - Shoes

LDC two extra connections Clamped on other LDC and plate Measurements inside and outside Current levels outside higher on avg for 4 vs 2 connections Less current toward inside of pedestal Path of least resistance! RFI Mitigation 2 - Measurements

RFI Mitigation 3 - Shielding

Chiller plant no earthing philosophy – floating Cables going through to pedestal interior Possible path for induced currents Consider optimal earthing options Chiller Plant Earthing 1

 No redirection of current  Shunted connection redirects current Chiller Plant Earthing 2

Conclusion Reverberation chamber method – relatively quick for testing cable shielding effectiveness or transfer impedance Lightning protection measures can be incorporated at MeerKAT design stage Elevation assembly might be reconsidered Pedestal RFI can be mitigated with correct shielding and cable terminations Correct earthing and terminations will aid in redirection of induced currents Electrons are sneaky!

T H E E N D Thank you for your time Any Questions? Veni, Vidi, Velcro ( I came, I saw, I stuck around )