1. Electrical Configuration and System Protection
Focus Coil
Electrical Configuration and System Protection

2. Circuit Configuration – Normal Operation
AMI 430 Controller (SS use AMI 420)
AMI regulates the output current
Ramp rate is set via the AMI to <30ma/s
DC contactor
AMI 430
Power Supply
Focus Coil
Energy Absorber
Dump Circuit
Sorensen 250A power converter
Energy absorber is needed during ramp down due to unipolar PSU

3. Circuit Configuration – Magnet Quench
DC contactor
AMI 430
Power Supply
Focus Coil
3 ohms
Energy Absorber
Dump Circuit
If a Quench is detected the DC contactor will opened
The magnet energy is then discharged into the dump circuit
Voltages of up to 700V can be generated across magnet
Earth connection at centre of resistors reduces voltage to earth

4. Power Converter Rack Thermal Test
Fans Activate

5. FC#1– Current Stability Measurement
AMI Controller – Stability Specification = 100ppm
Drift over 12.5 hours < 10mA
Tested with FC#1

6. RR2 Layout – rack allocation
QD System racks
Oxygen Depletion System
Auxiliary rack (Tracker & Diffuser)
FC & SS Control & Instrumentation racks
SS Ground Fault Protection rack
FC & SS Power Supply racks

7. Power Supply and Instrumentation Racks
Power supply system is air cooled and housed in single rack
Instrumentation is housed in a single rack including temperature monitors, heater controller and helium level indicator
The equipment provides monitoring and protection for the magnet
SS and FC racks in RR2

8. Control System Philosophy
VME system downloads the system configuration via the Ethernet connection.
Ethernet also provides the communication with the high levels of the control system
Allow parameters to be monitored / controlled via a GUI interface
The VME provides analogues to the plant via a serial interface
CANBus interfaces up to 30 status modules
Each status module contains relay outputs for control and opto isolated inputs for the interlocks

9. Standardised Control System with Plant equipment
Controls Interface
Super Conducting Magnet compressors
Power Supply racks
Standardised Control System with Plant equipment
All control interfaces are standardised.
A number of control racks are located inside the MICE Hall and rack rooms.
Each rack consists of VME crates, Canbus modules and ADC/DACs.
These racks control - vacuum, compressors, power supplies, tracker equipment, etc.
All controls equipment is modular and can easily be replaced – spares are available.
DL Control System
Quench data logger

10. Control Interface – Ramp Enable
Interlocks
Ramp Enable - Command
AMI 430 Controller
Insulating-Vacuum
PPS Guardline A
PPS Guardline B
PSU Rack Temperature
Earth Fault
Helium Level Low
PSU s/D Fault
Fast Ramp Down
SSD/SSU Turbo pumps
All interlocks are latched into the Control System
Volt free contact activates ramp enable
Any interlock will activate the ramp enable
Current automatically ramped down to Zero
Once activated controller is locked
DC Contactor will remain closed

11. Control Interface - DC Contactor
Interlocks
DC Contactor
Quench Detected
Activated by Volt free contact
DC Contactor - Command
Volt free contact sent directly to DC Contactor
Opening DC contactors at nominal current is highly likely to cause a quench
DC Contacts are latched closed
Volt free contact also sent to Control System
Can only be opened by Quench interlock
A Control system failure will not open DC contacts

12. Quench Protection – System operation
Voltage Tap Input
3 Voltage taps
Resistive measurement
Amplified
Central tap amplified
Outer voltage taps to provide reference
Isolated
Signal is isolated from the magnet
Compared
Window comparator used to compare signal
Relay de-energised
If signal is outside of the specified range
System Latched in the quenched state
Quench Triggered
Relay chain open circuit
Magnet Circuit breakers opened
Quench Detection Card
Quench Detection Crate

13. Quench Protection – System Operation (cont.)
System currently has two methods of setting the trip point.
Through a fixed resistor which currently sets the tripping threshold at 20mV
Through a variable resistor which can set the tripping threshold between 10mV and 600mV.
This function is switch selectable and is mounted on each card.
When a quench is detected several actions happen at once.
A signal is sent to activate the dump circuit
A signal is sent to control system to alert the operators
A signal is also sent to magnet power supplies and other equipment that may be affected by the quench to power down

14. Voltage Taps - Configuration
The voltage tap tripping voltages are set to 20mV for all of the HTS and LTS comparisons and approximately 600mV for the coil comparisons.
Four quench detection channels are connected across the HTS and LTS leads
Two channels are connected across the two coils of the magnet as this was required to achieve an overlap

15. QP System – Operating Characteristics

16. Data Logging
Each channel is connected differentially to each of the voltage taps
Each input channel is rated for >1kV
There are 16 channels with one allocated for the quench signal
2 of the channels will be used to record quench triggers from the SS magnets
The remaining 13 channels are used to monitor the coils, LTS and HTS leads
The processor stores 2 sets of triggered data and is automatically set via the ramp enable.
Currently only 1 minute of data is recorded at 1ms intervals.
Will be soon updated to 8 minutes
DC contactors open
600mV threshold
Quench signal activated

17. QP System – Key Operating Parameters
Quench detection circuit is based on a proven and reliable 30 year old design concept from the Paul Scherrer Institute (PSI).
Each QD channel uses 3 voltage taps to monitor the voltage differences progressively across the SC magnet.
Each QD channel is rated for 1.5kV galvanic isolation between channel and earth and 1.5kV channel to channel.
The power supply crate contains commercially available power supplies with built-in n+1 redundancy
The Quench detector system has been used with the decay solenoid and focus coil since early 2013 and has successfully sensed over 20 quenches whilst training both FC’s during training in R9 and finally in the Mice Hall.

18. Protection Against Transient Overvoltage
MICE Hall main
Sub-station
Transient Suppression also installed on UPS board
Transient Suppression installed on main distribution board.
Preventing lightning strikes and disturbances on the supply network damaging equipment.
Transient suppression also being fitted on UPS board due to isolated double conversion technology.

19. (short duration – unlikely to cause quench)
Power Converters and Controllers susceptibility to network disturbances
FC - AMI 430 Controller – AC supply threshold measured at 159V (spec -176V).
Once AC supply lost the AMI resets and output is set to ZERO.
This will cause a fast ramp (circuit components limited) – likely to cause a quench – tested and verified.
DCCT supply failure is also likely to cause a quench.
FC – Sorensen 250A PSU – if AC supply is lost then a fast ramp will be initiated until power returns.
Again likely to cause a quench.
Some of the recorded network disturbances could have affected the FC power converter.
(short duration – unlikely to cause quench)
FC – AMI 430 Controller (SS use AMI 420)
FC - Sorensen 250A power converter (main)
230 Vac (operating range Vac) – 76% of 230Vac
400 Vac (operating range Vac) – 85% of 400Vac

20. Rack Room 2 – UPS Inverter and Batteries
Two 30kVA UPS (inverter) have been installed and support Control, Power Supplies, Vacuum and Instrumentation in RR2.
UPS for Critical Load
Batteries
The 2 x 30kVA UPS operate in parallel and share a common battery pack.

21. Emergency - Ramp Down
A Ramp Down button is installed on the FC power supply racks
This button interface directly with the AMI 430 controller
It will ramp the current to zero at the programmed ramp rate. (between 10 and 30ma/s)
Once activated the AMI controller is locked until the current reaches zero
Note – this is not a Fast Ramp Down as installed on the SS magnets
If the DC contactor was opened it would probably quench the magnet
A risk assessment concluded that quenching the magnet should be avoided even during an emergency
Note - Emergency Ramp Down on the SS opens the DC contacts and ramps the current to Zero quickly
Racks installed in RR2

22. Questions?