ISIS Electrical Engineering Group

Mike Glover

ISIS Electrical EngineeringGroup Structure

Group Leader

ESSOPulsed Power

PSU Development

DC Power

Controls &Electronics

3Staff

4Staff

5Staff

3Staff

9Staff

ISIS Electrical EngineeringGroup Structure

Mike GloverGroup Leader

ESSO Pulsed Power PSU DevelopmentDC PowerControls &Electronics

VacancySection Leader

Geoff MartinEngineer

Adrian McFarlandSection Leader

Stephen RuddleEngineer

Jim GraySection Leader

Tim CarterEngineer

Husam Al-HakimEngineer

Matt NorthEngineer

Chris GascoyneTechnician

Steve StonehamSection Leader

VacancyEngineer

John BowsleyContractor

Steve WestEngineer

Andy KimberEngineer

Martin HughesGraduate Engineer

Neil FarthingContractor

Steve WarnerOffice Manager

VacancyIT Manager

Neil KellyCAD

Martin DobbsCAD

Vacancy CAD

Vacancy CAD

Austine BrineContractor

Paul WadeContractor

Areas of Responsibility

• ISIS Synchrotron Power Supplies

• ISIS Extracted Proton Beam Line Power Supplies

• ISIS Neutron Beam Line Chopper Power Supplies

• Electrical Engineering of ISIS Control Systems for:

• Vacuum Systems

• Water Plant Systems

• Electrical Engineering of Neutron Instrument Beam Line Installations

ISIS Synchrotron Power Supplies

• Main Magnet “White Circuit”– 14.4kV 650ADC 400AAC

• Injection & Extraction Septum– 5kA & 10kA 50V DC

• Injection Dipole– 50Hz 13kA 500µS Flat Top 100µS Rise Time

• Ring Steering & Trim Quadrupoles– 4 Quadrant 150kA/S 250 Amp Programmable

• Fast Extraction Kicker Magnets– 50Hz 40kV 5kA 500nS Flat Top 80nS Rise Time

Injection Septum

•Deflects the injected beam into the aperture of the injection dipole magnet and onto the foil

•200kW

•5000 Amps

•40V

•1416 Transistor Regulator

•100ppm stability

Extraction Septum

Magnet Bend 21º

10,000 Amps 50V

11kV Supply Rectifier Transistor Regulator

4 Sets of 24 Transistor Banks

2304 Transistors

Extraction of Beam

• At Extraction

– Protons Circulating at 800 MeV

– Two bunches with 200 ns gap

• Extraction System

– 3 fast kicker magnets

deflect the beam into …

– a septum magnet

which lifts it into the EPB

• Kickers need to be fast to avoid beam loss

– Go from zero to full field between passage of bunches

Extraction Details

• Kickers

– 3 units give 15 mr kick

– Rise Time 80 nS

– Flat Top 500 nS

– 5000A

– 40kV

– 50Hz pulsed

• Septum

– ~ 8 m downstream

– 8 Turn, 8900 A

– DC

– 1.8 m long (21 degrees)

– Lifts beam out of machine

ESSORing Vacuum PLC Control System

ESSONeutron Beam Line Installations

•Complete electrical design

•Electrical Supply

•Detector Cabling

•Chopper Cabling

•Vacuum System Controls

•Several kilometres of cabling per beam line

Power Systems and the ISIS Synchrotron

Andrew Kimber

• Main magnet systems• MM Power Supply and the White Circuit

• Capacitor bank replacement• UPS• Replacement 1MJ Storage Choke

• Summary

Outline

Magnet systems

• Main Magnets

10 Bending Dipoles10 Singlet Quadrupoles10 Focussing Doublet

Quadrupoles.

• Corresponds to 10 superperiods

Main magnet power supply

250A

1050A

Main magnet power supply

For successful acceleration the same magnetic field is required in all the main magnets

Main Magnets per super period:1 Dipole1 Singlet Quadrupole1 Doublet Quadrupole

How do we connect these?One power supply per super periodMain Magnet System operates at 14.4kVCurrent changes from 250A to 1050 Amps

Peak Power = 15.1 MVAFor 10 super periods the Peak Power

Required = 151 MVA

Excessive Power Required !

Main magnet power supply

Magnets have InductanceInductance can store energy E = ½ LI2 Capacitors also store energy E = ½ CV2

Resonate the stored energy between Inductor and capacitor:

With no losses in the system the impedances of the Inductance and the Capacitance would be identical and energy would be transferred with an alternating current between them and at a resonant frequency.

Inductance reactance XL = Capacitive reactance XCωL = 1/ωC ω = 2π f Resonant Frequency f = 1/(2π√LC )

Main magnet power supply

• Normal Temperature Magnets have Resistance

• Capacitors have losses

• Cables have losses

• If the losses << Inductance we have a high ‘Q’ oscillating system.

• We just require to supply make up power for the resistive and AC losses in the Magnets, Cables and Connectors.

The White Circuit

WHITE CIRCUIT M G White, Princeton (1956) CERN Symposium

• Oscillate the magnet cell using capacitors and choke.

• Connect all the magnets together electrically and same current flows through each magnet.

• Permit DC bias current through split choke secondary winding

• Power required is to make up for the resistive losses in the copper, ac losses in the magnets and power supply losses.

IM = IDC – IAC cos ω t

Total of 1.75MW (150MVA peak for non resonant circuit)

The White Circuit

Main magnet power supply

• Replace capacitor bank with smaller more efficient units. • Replace the Motor Alternator Set with a UPS System• Replace the Choke.

– Split the Choke into 10 separate units and build spare as well.

PROGRESS TO DATECapacitor bank replaced (2002)

UPS system currently on order.

Build a scale model to prove theory of split choke.Scale model chokes currently being ordered.

Old Capacitor Banks

New Capacitor Banks

Replaced in 2002

Smaller units, space used for1 old bank is now used for 5.

Motor Alternator Set

Previous Motor Alternator Set

• Electromechanical• Single phase output• 2 phases connected line to line and 1 disconnected• Alternator phase locked to ISIS 50Hz reference• 100Hz induced harmonic between raw mains and reference signal

DCMotor Alternator

BrentfordExcitation

PSU 12KVA

Mains supply

Phase locked toISIS 50Hz reference

signal

transformer

5KVsingle phase

3.6KVsingle phase

Storagechokeand mainmagnets

shaft

Current Motor Alternator Set

DCMotor Alternator

BrentfordExcitation

PSU 12KVA

Mains supply

Phase locked toISIS 50Hz reference

signal

transformer

5KVsingle phase

3.6KVsingle phase

Storagechokeand mainmagnets

shaft

UPS

Phase locked toISIS 50Hz reference

signal

• Alternator and UPS phase locked to ISIS 50Hz reference • Factor of 2 improvement in AC stability

New UPS system

• Motor alternator set replaced with 4 300KVA units (1 redundancy)• UPS units currently on order• Installed by Q4 2004

transformer

3.6KVsingle phase

Storagechokeand mainmagnets

240Vthree phase

Gray convertercircuit

720Vsinglephase

Current 1MJ, 2H Storage Choke

Ex-NINA, manufactured in the 1960’s

Ten interleaved primary and secondary windings

Choke windings and core: 90 tonnesTotal weight (inc. oil): 120 tonnes

30 years of service

State of insulation unknown, leaks oil, failure would result in ISIS being down for extended period of time

Storage Choke

Replacement chokes

…X10

Current 2H storage choke

10 off replacement 200mH chokes

1/5 scale models 40mHMinimise financial and technological riskDue September 04

Full scale prototype/spare

Replacement chokes

Flux DensityB (T)

2.150

1.935

1.720

1.505

1.290

1.075

0.860

0.645

0.430

0.215

0.000

Flux DensityB (T)

1.570

1.413

1.256

1.099

0.942

0.785

0.628

0.471

0.314

0.157

0.000

• Most probable design is a ‘frame’ type storage choke

Energy stored (air gaps) = ½ L I2

Energy stored/unit volume = ½ μ0 B2

• Calculate dimension of air gapsFor 200mH, 1010A, 100KJ, 0.9T: Volume ~0.3m3

• Size and distribution of these critical in controlling losses

Replacement chokes

Testing of scale models to take place September 2004

• Losses• Stray magnetic fields• Leakage inductance• Linearity• Noise (mechanical)• Cost

Summary

• New capacitor banks– Installed 2002

• New UPS system– Installed by Q4 2004

• New split choke system– Scale model testing Q4 2004– Prototype and production chokes 2005/6