TE/MPE/EE - LHC Knud 8/3/2012 Project for Upgrade of the Electrical Circuits, the Powering Scheme and the Quench Heater Supervision for Enhanced Monitoring Topics: The motivation for undertaking the upgrade Description of the implementation of the required modifications The expected performances The strategy for the execution Cost estimations Schedule & Planning DYPB / DQLPU – Local Quench Protection Facilities for the Arc Dipoles

TE/MPE/EE - LHC Upgrade of the QPS Electrical Systems of the DYPB’s Reasons for the proposed changes: 1. DQHDS: The present discharge voltage measurements are considered insufficient for proving the integrity and conformity of the quench heater circuits and as a tool for an early warning of circuit failure - Defects (cracks) have been detected in at least one dipole heater circuit. The flaw is considered as a potential risk of strip rupture in a certain batch of dipoles but also other types of failures have been observed. - It is feared that an electrical arc at the level of a strip heater can damage the coil insulation to a point where the withstand to ground is being affected. - If detected early enough the heater system can be reconfigured with the use of LF heaters and the suspect strip will be disconnected. The re-connection is made in the Crawford box. - So far 8 LHC main dipoles have actually experienced heater circuit failures and were reconfigured (C15R1,A22R1,C32R1,A21L3,C17R4,C31R4,A32L7 and B21L8). - As a consequence full-voltage test discharges have been avoided in the main circuits for the last two years – now replaced by our LV discharge (from 100V). - Operation at nominal current and the future magnet training campaign stress the need for the more powerful monitoring tools which will be provided by the suggested upgrade.

TE/MPE/EE - LHC Upgrade of the QPS Electrical Systems of the DYPB’s Reasons for the proposed changes: 2. Powering: The LV powering scheme for energizing the detector electronics of the iQPS system for the main magnets (DQLPU crate) was built and has remained non-redundant from a UPS point-of-view, also after the introduction of the nQPS system which was designed with UPS1/UPS2 powering redundancy - The DQQDS (SymQ) system will, to a certain extend, act as back-up for the ‘asymmetric’ detection of iQPS in case of a failure of UPS1 (now UPS2). However, with the higher thresholds longer detection time can be expected. - The change to a UPS-redundant powering scheme would require important changes to the DQLPU motherboard and back-panel. The ‘crash program’ of 2008/9 did not allow such modifications. The update of the local protection unit would be an appropriate occasion. - Although considered very reliable, the commercial ‘Syko’ tri-volt, switched-mode converters used in the DQLPU s have recently shown some weaknesses (~25 units did not restart after repowering this winter and some evidence that the current rushes observed on the F3 UPS net are caused by the ‘Syko’s’). - The 872 CERN-made (QPS/EPC) linear power supplies with four output stages (the Power-Packs DQLPUS) have worked impeccably for two years and could be the model for a new version of converter suitable for the iQPS upgrade. - It would be interesting to integrate the signal and power patches, introduced with the nQPS, into a new interface (shuffling) module required for the upgrade.

TE/MPE/EE - LHC Upgrade of the QPS Electrical Systems of the DYPB’s Based on these considerations, the proposal for modifications to the electrical systems and interconnections of the existing Local Protection Units consists in: Replacing the existing ‘Crawford’ box, the ‘Syko’ power source and all the patches with a single, new Interface Module (DQLIM) which will contain ALL the requested components and features, incl. most elements of the new enhanced heater circuit supervision. - The ‘Crawford’ shuffling module was never optimized from the point of view of volume and maintaining it would leave insufficient space for the new items. - In order to protect all components they must be mounted inside the frame of the DYPB rack - Such a topology would lead to less ‘external’ electrical interconnections. - The complete module can be pre-manufactured resulting in short installation times. - The new module can be tailor-made to the requirements for e.m. shielding. - The new module can, if decided so, incorporate the expensive connectors and other items recuperated from the dismantled ‘Crawford’ unit.

TE/MPE/EE - LHC Upgrade of the QPS Electrical Systems of the DYPB’s Housing the following new and old sub-systems inside the new Interface Module: - Two identical, linear power supplies (DQLPUR) each with four secondary outputs V and 5.4 V), inspired by the design, component selection and experience from the creation of the nQPS Power Packs. - An energy storage module (Super capacitor bank) for each new Power Pack. - The power distribution from the redundant converters to the crates DQLPU-A and DQLPU-S - Four screened, pulse current transformers, with their individual bias system (housed in individual compartments for additional magnetic decoupling). Bias system requires a 200 mA current source. -The connections for the injection of the DC heater test current (from the DQLPU-A), the two separation / isolation switches (one per pole), the anti-return power diodes and the current- limiting resistors for the voltage measurement lines. - The electrical connections of the existing ‘Crawford’ box and the signal- and power patches, adapted to the new configuration. More details are given in the ECR: ‘Installation of Enhanced Quench Heater Supervision System for the LHC Main Dipole Magnets’ - ready for circulation.

Existing Interconnection Scheme for iQPS & nQPS, Power and Signals between the Individual Elements Valid for Dipole ‘B’ position

Proposed Interconnection Scheme for iQPS & nQPS, Power and Signals between the Individual Elements Valid for Dipole ‘B’ position of the Upgraded DYPB

Existing Interconnection Scheme for iQPS, Power and Signals between the Individual Elements Valid for Dipole ‘C’ position (similar for ‘A’ position)

Proposed Interconnection Scheme for iQPS Power and Signal transmission between the Individual Elements Valid for Dipole ‘C’ position (similar for dipole ‘A’ position) of the Upgraded DYPB

Components of the existing DYPB / DQLPU / DQLPU-S / DQHDS/ ‘Crawford’ box The ‘Crawford box’ for a dipole protection unit DQLPUS Local Protection rack DYPB for dipole position ‘B’

TE/MPE/EE - LHC The New Components 1: Broadband Pulse Current Transformers (CT) Housing - Two Two prototype pulse measurement transformers with shielding case and precision burden resistor. One made for operating with magnetic bias from one-winding 200 mA bias current Current measurement transformer before housing - Precision current measurements of the 4 simultaneously triggered heater discharge pulses are provided by 4 identical, shielded CT’s, designed specially for the 80 A peak τ = 80 ms pulse current and equipped with precision Burden resistors. - To minimize distortion of the pulse shape, the ferrite –cored CT has been designed for values of leakage inductance and distributed capacitance as well as a high open-circuit inductance. - Magnetic Bias allows important reduction in volume and cost (for same measurement performance). The bias requires a 200 mA dc excitation current. - Measurement accuracy depends on the dI/dt: 1 % at 1τ, 2 % at 2τ (expected, tbc) - Producer: ‘Lilco Ltd.’, Isle of Orkney, UK. - The two prototype trfo’s are ready for testing. To be performed in an accredited Test Institute (IPH - Prüffeld für Elektrische Hochleistungstechnik" GmbH, East-Berlin). - Unit cost of the CT‘s (budget prices): Un-biased type: 100 CHF/unit, biased type: 70 CHF/unit. Burden resistor: 100Ω, 0.1%, ¼ W

TE/MPE/EE - LHC The New Components 2: The Power Packs for iQPS Redundant Powering DQLPUR The new natural-convection air-cooled power modules shall be derived from the Power Packs (DQLPUS) which were developed by QPS and Industrialized by EPC for the nQPS. They shall supply two independent, regulated DC voltage outputs: DC output 1a: +5.4 V, +/- 2%, with fully floating output (2.5 kV isolation) DC output 1b: ±15 V, +/- 10%, with fully floating output (2.5 kV isolation, DC outputs 1a and 1b shall share the same reference voltage) DC output 2a: +5.4 V, +/- 2%, with one ground potential reference DC output 2b: ±15 V, +/- 10%, with one ground potential reference, for powering the relays of the DQHDS and the DAQ systems (DC output 2a and 2b must share the same ground potential reference) The current ratings of the two 5.6 V outputs will be fixed as soon as the power consumptions have been determined. The topology is based on input transformers for voltage step-down and galvanic isolation, relays on the power input level to allow for remote power cycling of the two 5.6 V outputs, diode rectifiers, smoothing capacitors, linear regulators on the LV-side of the toroidal transformers and super-capacitor banks for voltage hold-up of the two 5.6 V outputs. Opposite the nQPS Power Packs, which are mounted separately on the frame of the DYPB racks, the new supplies will be designed as a very compact version for insertion into the DQLIM interface module. The heat dissipated from the transformers and the linear regulators shall be conducted outside the crate. In total 2’500 units, incl. spares are required to cover the needs of the dipole local protection units.

TE/MPE/EE - LHC Frame conditions 1: Cost Estimate: Supplies only (based on 100% deliveries from Industry). Estimations made by scaling using previous contracts of similar supplies Equipment Unit (or set) cost CHF Quantity installedQuantity Spares Total cost CHF Power Packs iQPS version (DQLPUR)380, '031’320 Shuffling box DQLIM720, ’040 Pulse Current Transformers (bias type)70, ’960 Associated new sets of Interconnecting cables350, ’700 GRAND TOTAL2’741’020

TE/MPE/EE - LHC Frame conditions 2: Cost Estimate: Human Resource Cost (PJAS, FSU) Estimations made by scaling from previous jobs Work Description Quantity people (team) Time per sector (hours) Total Cost Whole Machine CHF Removal of the Crawford box and associated cables61732’640 Installation/connection of the new sets of cables6815’360 Installation of new Interface Module (DQLIM)6917’280 System Tests – surface building ’280 System Tests - tunnel 22012’800 Total 143’360 Average hour rate used: 40 CHF TOTAL PROJECT COST FOR EE-SECTION: 2’884’380 CHF

TE/MPE/EE - LHC Frame conditions 3: Planning – Schedule Preliminary ! Assumption: No Marked Survey and Restricted Tender Procedure ! Activity: Target date for completion Concept / design ready for prototype: DQLPUR14 May 2012 Concept / design ready for prototype: DQLIM5 May 2012 Two prototypes ready for type testing and endurance tests DQLPUR 21 June 2012 Two prototypes ready for type testing and endurance tests DQLIM 2 July 2012 Successful completion of testing of the CT prototypes 1 May 2012 Successful completion of type testing of first complete prototype system 31 Aug 2012 Production Readiness Review (CERN) Mid-Sept 2012 Orders placed with industry Early Oct 2012 Production Readiness Review with Industry Mid Nov Deliveries for 1 st Sector End January 2013 Delivery rate 1 sector/month