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ISIS Electrical Engineering
Group
Mike Glover
ISIS Electrical Engineering
Group Structure
Group
Leader
ESSO
DC
Power
Pulsed
Power
PSU
Development
Controls &
Electronics
9
Staff
3
Staff
4
Staff
5
Staff
3
Staff
ISIS Electrical Engineering
Group Structure
Mike Glover
Group Leader
ESSO
DC Power
Pulsed Power
PSU Development
Controls &
Electronics
Steve Stoneham
Section Leader
Vacancy
Section Leader
Adrian McFarland
Section Leader
Jim Gray
Section Leader
Tim Carter
Engineer
Steve Warner
Office Manager
Geoff Martin
Engineer
Stephen Ruddle
Engineer
Husam Al-Hakim
Engineer
Matt North
Engineer
Vacancy
IT Manager
Chris Gascoyne
Technician
Vacancy
Engineer
Steve West
Engineer
Neil Farthing
Contractor
John Bowsley
Contractor
Andy Kimber
Engineer
Neil Kelly
CAD
Martin Dobbs
CAD
Vacancy CAD
Vacancy CAD
Austine Brine
Contractor
Paul Wade
Contractor
Martin Hughes
Graduate Engineer
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
ESSO
Ring Vacuum PLC Control System
ESSO
Neutron 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
Outline
• Main magnet systems
• MM Power Supply and the White Circuit
• Capacitor bank replacement
• UPS
• Replacement 1MJ Storage Choke
• Summary
Magnet systems
• Main Magnets
10 Bending Dipoles
10 Singlet Quadrupoles
10 Focussing Doublet
Quadrupoles.
• Corresponds to 10 superperiods
Main magnet power supply
1050A
250A
Main magnet power supply
For successful acceleration the same magnetic
field is required in all the main magnets
Main Magnets per super period:
1 Dipole
1 Singlet Quadrupole
1 Doublet Quadrupole
How do we connect these?
One power supply per super period
Main Magnet System operates at 14.4kV
Current changes from 250A to 1050 Amps
Peak Power = 15.1 MVA
For 10 super periods the Peak Power
Required = 151 MVA
Excessive Power Required !
Main magnet power supply
Magnets have Inductance
Inductance 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 XC
ωL = 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 DATE
Capacitor 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 for
1 old bank is now used for 5.
Motor Alternator Set
Previous Motor Alternator Set
Mains supply
DC
Motor
Brentford
Excitation
PSU 12KVA
5KV
single
phase
shaft
3.6KV
single
phase
Alternator
Storage
choke
and main
magnets
transformer
•
•
•
•
•
Phase locked to
ISIS 50Hz reference
signal
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
Current Motor Alternator Set
Brentford
Excitation
PSU 12KVA
Mains supply
Phase locked to
ISIS 50Hz reference
signal
UPS
DC
Motor
5KV
single
phase
shaft
3.6KV
single
phase
Alternator
Storage
choke
and main
magnets
transformer
Phase locked to
ISIS 50Hz reference
signal
• Alternator and UPS phase locked to ISIS 50Hz reference
• Factor of 2 improvement in AC stability
New UPS system
240V
three
phase
720V
single
phase
3.6KV
single
phase
Storage
choke
and main
magnets
transformer
Gray converter
circuit
• Motor alternator set replaced with 4 300KVA units
(1 redundancy)
• UPS units currently on order
• Installed by Q4 2004
Storage Choke
Current 1MJ, 2H Storage Choke
Ex-NINA, manufactured in the 1960’s
Ten interleaved primary and secondary windings
Choke windings and core: 90 tonnes
Total 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
Replacement chokes
Current 2H storage choke
…X10
10 off replacement 200mH chokes
1/5 scale models 40mH
Minimise financial and
technological risk
Due September 04
Full scale prototype/spare
Replacement chokes
• 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 gaps
For 200mH, 1010A, 100KJ, 0.9T:
Volume ~0.3m3
• Size and distribution of these critical in controlling losses
Flux Density
B (T)
Flux Density
B (T)
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