1. Overview of the CLIQ Units Project
Knud Dahlerup-Petersen, Félix Rodríguez-Mateos
TE-MPE Technical Meeting
CERN, April

2. Outline Introduction and general aspects Choice of main components
Safety aspects
The mini-Review and principal outcome
A glance to the future of CLIQ
The Team

3. Introduction and general aspects

4. A new hybrid protection system for high-field superconducting magnets
Several units of CLIQ power supplies have been manufactured by the MSC Group over the last years and used at CERN for testing of different magnets in SM18
We do not present here the “ad-hoc” design of those units
This previous design has given the needed flexibility to optimize parameters as capacity, voltage/current, frequency and dumping time constant
There is now a request from MSC to the MPE Group to produce 3 units, 2 of which will be sent to FNAL by the end of May’15. The third one will serve as spare
If successful, this project will continue with more prototypes and ultimately a production of series for Hi-Lumi upgrade magnets
A new hybrid protection system for high-field superconducting magnets
E Ravaioli, V I Datskov, G Kirby, H H J ten Kate, and A P Verweij

5. Some facts and boundary conditions
The EE Section got the mandate in early February 2015
Delivery for end of May 2015
Choice of components was determined by the very short delivery time
Resource organization was affected by the short lead time, with involvement of an important fraction of the section members
Experience from the DQHDS is an important feature, although being of a different nature (only discharge)

6. Choice of main components

7. Capacitors (1)
The CLIQ power unit is not only a supply, it is an energy exchanger
This will lead to the characteristic ringing, which is being increasingly damped by the resistances in the circuit, mainly the rapidly increasing resistance of the quenching coil, but also by the series-equivalent resistance of the capacitor bank and cable leads
The ringing leads to both positive and negative voltages on the storage capacitors within one current direction
Typical CLIQ discharge (Emmanuele)

8. Capacitors (2): selection
The storage capacitor bank for CLIQ must, according to above considerations, be of bipolar type
Further requirements
Low internal series-equivalent resistance
High capacitance density
Minimum bus bar work for connection
Switch between 1 or 2 capacitors
Selected type
Self-healing, dry type, metallized polypropylene
Data: 500 V, 2 x 40 mF, 2 x 44 kg (from LHC QF/QD snubber capacitor spares)
With over-charge protection and over-pressure indication
Stored energy: 10 kJ

9. Charging circuit
The LHC 3-step type of charger is replaced by a 100 mA constant-current charger of commercial origin - tailored to our application. Full charging time around 400 s. Charging voltage shall be adjustable in steps of 50 V (manual commutation, up/down). Charging from 110 V, 60 Hz as from 240 V, 50 Hz. Capacitor voltage and charging current shall be displayed as well as the end of charging state.
16/04/2015
MPE Technical Meeting

10. Thyristors (1)
Discharge characteristics of bi-directional nature (discharge / recharge currents) => semiconductor switches in a bi-directional arrangement have been chosen
Good experience from the LHC quench discharge heater units with the use of thyristor switches => decision to keep the thyristors option for the CLIQ units
Thyristors will be used in both directions in order to assure a ‘certain separation’ of the main magnet powering circuit from the heater circuit outside the provoked coupling period
The two opposite thyristors shall be fired simultaneously for 0.5 s. No trigger redundancy in each unit is considered necessary

11. Thyristors (2): selection
Two candidate thyristors have been considered:
Single Thyristor used for fast opening pulse to LHC main circuit energy extraction switches (BCM). To be doubled
Bi-directional Thyristor for energy management. Approved by ABB for the CLIQ application. Two thyristors in one wafer
The thyristor firing shall be provoked through application of a train of pulses, from a 12 kHz generator through pulse transformers.
Discharge current shall be measured by adequate AC current transformer (6kA peak, 10-3 accuracy). 1. 2.

12. Safety aspects

13. A main breaker (or a switch + fuse), accessible on the outside panels of the CLIQ unit, shall assure not only interruption of the input power but equally switch-in a bank of discharge resistors which will assure an automatic ‘internal’ discharge of the complete capacitor bank. The total discharge time shall be 1 minute maximum.
In addition to a clear indication of the actual charging voltage/current (analog voltmeter or galvanometer per capacitor), a visible indicator shall show safe conditions (<40V).
After re-powering from the mains input, there shall be no automatic re-charging of the capacitor bank (system is latched). Charging shall be initiated manually.
After a discharge the system is automatically latched. Recharging only by manual activation.
Activation of the equipment stop button shall initiate an internal discharge of the capacitors
For changing the capacitance value (switch between 1 or 2 capacitors), possibilities should be studied that do not imply opening of the rack (lockable switch that can only be activated after discharge of the capacitors)

14. The mini-Review and principal outcome

15. Objectives Validation of the implementation of the concept
Coherence of the choices with respect to the established functionalities
Correctness with integration and implementation according to the electrical standards applicable
Safety aspects

16. Panel Jean-Paul Burnet, TE/EPC Alexandr Erokhin, TE/MPE
José Carlos Gascón, DGS-SEE-XP
Christian Giloux, TE/MSC
Andrzej Siemko, TE/MPE (ex-officio)
Yves Thurel, TE/EPC
The mini-Review took place on April 8, 2015

17. Agenda 1. Scope and objectives of the review Félix Rodríguez Mateos
10’
2. Introduction to the CLIQ protection method
Emmanuele Ravaioli
15’
3. General aspects of the design, choice of components and safety issues
Knud Dahlerup-Petersen
4. Details of the design
Joaquim Mourao
30’
5. Integration and implementation
Mathieu Favre
6. Discussion and questions from the panel
All

18. Recommendations (1) Components
use the higher rated ABB thyristors which give larger margin in all parameters
set 0.5s for the duration of the train of pulses
discharge resistors should not to be mounted on a PCB, 20 resistors in series should not be used
thyristor firing circuit to be completed (paying attention to magnetization of the pulse transformers)
use an AC current transformer instead of a LEM for discharge current measurement
qualify the AC/DC converter in terms of EMC or use qualified material
16/04/2015
MPE Technical Meeting

19. Recommendations (2) Safety Project Management
maximum discharge time should be 1 min
use a switch that a) triggers internal discharge, b) short-circuits capacitors and c) allows opening the cubicles (if required)
use a properly rated circuit breaker for ON/OFF and not a “sectionneur”, or add a fuse
earthing issue: for such mobile units as the ones under discussion the earth connection given through the powering mains is enough
no need for special screws, idem for internal plastic covers
install galvanometers to show the charge/discharge of each capacitor
Project Management
prepare test programme well in advance
prepare documentation for the future users
structure the project (mandate, functional specifications, technical specifications, planning, responsibilities, etc)
16/04/2015
MPE Technical Meeting

20. A glance to the future of CLIQ

21. Near future plan for protecting magnets with CLIQ
LHC-high luminosity upgrade
QXF is the inner triplet large quadrupole strings of magnets either side of the ATLAS and CMS.
Model testing in Fermi-lab (two units plus spare)
Model testing in CERN (Two units plus spare)
First long magnet prototype test in BNL (Two units plus spare)
Production of 32 + spares units for LHC-HL, assuming two units per magnet.
Courtesy Glyn Kirby

22. Longer term possibilities for use in LHC-HL upgrade
CERN
Orbit correctors for LHC-HL: Twin aperture independently powered dipole
MQY for LHC-HL with pushed performance for the upgrade. Currently being tested in SM 18 at CERN.
Each magnet would need 4 units
LHC: Main dipole will be tested at CERN in SM18 in the following months in view for rapid repair of LHC systems
Outside CERN
KEK Japan: D1, LHC-HL Single aperture standalone dipoles requiring 4 units + spares
CEA France: Q4 Twin aperture quadrupoles ~ 16 units + spares
GSI: they are investigating for use with their magnet systems
Further future
16 Tesla hybrid FCC models
block design & cos-theta design could benefit from CLIQ
CCT design (canted cosine theta) may rely on CLIQ; LBNL have requested two units for future testing of their 16 Tesla CCT magnet.

23. The team

24. Members of the team in MPE
Knud Dahlerup-Petersen
Arnie Dinius
Mathieu Favre
Joaquim Mourao
Bozhidar Panev
Emmanuele Ravaioli
Felix Rodriguez Mateos
Other contributors: Gert Jan Coelingh
Alexandr Erokhin
Yan Bastian