TE-MPE -EI 23/6/2011,Antonopoulou Evangelia RQS circuit Simulation results of Quench Antonopoulou Evangelia June 2011 Thanks to E. Ravaioli

TE-MPE -EI 23/6/2011,Antonopoulou Evangelia General Information – RQS circuit Type600A Imax600A ConverterRPMBA MagnetMQS # of m.4 EEYes 2

TE-MPE -EI 23/6/2011,Antonopoulou Evangelia Powering subsector A12 Circuit RQS.A12B2 Power Converter Attributes R crowbar 0.05Ω Main parameters R tot measured Ω L tot0.124 H Inductance per aperture0.031 H Quench Protection System Energy ExtractionDQEMC Extraction Resistance700 mΩ Parallel Protection Resistor per Magnet0.25 Ω 3

TE-MPE -EI 23/6/2011,Antonopoulou Evangelia 4

Improved Schematic-RQS circuit (Main Circuit) 5 Power Converter CrowbarMagnets and Parallel Resistances EE System Resistance of the Busbar Simulation of the Switches Earthing point

TE-MPE -EI 23/6/2011,Antonopoulou Evangelia Latest Schematic-RQS circuit(1/2) 6 Thermal Model Main Circuit

TE-MPE -EI 23/6/2011,Antonopoulou Evangelia Latest Schematic-RQS circuit(2/2) 7 Thermal Model Electrical resistance Thermal resistance Thermal capacitance Thermal resistance of the insulation layer Magnetic field Inductance Magnetic transfer function Magnet 1 Magnet 2Magnet 3Magnet 4

TE-MPE -EI 23/6/2011,Antonopoulou Evangelia Crowbar The system is based on a 50 mΩ Power Resistance series back-to-back thyristors being fired at a given output voltage, and then providing a safe path for magnet current 8

TE-MPE -EI 23/6/2011,Antonopoulou Evangelia Energy Extraction System In all 600 A DC-current corrector circuits, the extraction facilities are inserted in series with the magnet chain. During normal operation the ex-traction breaker remains closed, herewith by-passing the dump resistor. In case of a fast power aboard or a quench of a magnet, the extraction breaker will be forced open, herewith switching the current to the dump -resistor. The extraction equipment is based on three individual, series-connected, high-speed, electro- mechanical AC circuit breakers 9

TE-MPE -EI 23/6/2011,Antonopoulou Evangelia Simulation of the Energy Extraction System 10

TE-MPE -EI 23/6/2011,Antonopoulou Evangelia The resistance of the switches in the EE system 11 Resistance of the switches: Parabolic=2ms exponential=11ms

TE-MPE -EI 23/6/2011,Antonopoulou Evangelia Snubber Capacitor The electrical arc, between the breaker’s contacts, causes significant erosion of the contact surfaces. In the LHC 600 A EE systems the arcing time attains typically 7 ms at ultimate current leading to sufficient damage and required maintenance after just a few commutations. To minimize the arc influence and reduce the opening time, a capacitor bank is introduced across the breakers with the following characteristics: - The capacitor voltage rating shall exceed the peak extraction voltage of 420 V. - Internal inductance (Lesr < 80 nH) and resistance (Rs < 6 mΩ shall be low. - Gives a capacitor value between 0.14 and 1.4 mF. Experiments have shown that the optimized capacitor value is 0.8mF. 12

TE-MPE -EI 23/6/2011,Antonopoulou Evangelia Simulation results of the influence of the snubber capacitor (1/3) 13 Without the snubber capacitor the arcing time attains 8ms

TE-MPE -EI 23/6/2011,Antonopoulou Evangelia Simulation results of the influence of the snubber capacitor (2/3) 14 With the snubber capacitor the opening time is reduced in 3ms

TE-MPE -EI 23/6/2011,Antonopoulou Evangelia Simulation results of the influence of the snubber capacitor (3/3) 15

TE-MPE -EI 23/6/2011,Antonopoulou Evangelia Simulation of the switches’ opening

TE-MPE -EI 23/6/2011,Antonopoulou Evangelia Data of PM_Browser

TE-MPE -EI 23/6/2011,Antonopoulou Evangelia 18

TE-MPE -EI 23/6/2011,Antonopoulou Evangelia Current in the RQS circuit comparison with PR_Browser data 19 Simulation: RQS.A34B2 PM_Browser event: _RPMBA.UJ33.RQS.A34B2

TE-MPE -EI 23/6/2011,Antonopoulou Evangelia Current in the Power Converter and the Crowbar →When the Power Converter is shutted down all the current pass by the crowbar until the discharge of the circuit. 20

TE-MPE -EI 23/6/2011,Antonopoulou Evangelia Voltage across the Crowbar 21

TE-MPE -EI 23/6/2011,Antonopoulou Evangelia Current in the circuit 22

TE-MPE -EI 23/6/2011,Antonopoulou Evangelia Current in the RQS circuit comparison with PR_Browser data 23 Simulation: RQS.A23B1 PM_Browser event: _RPMBA.UJ33.RQS.A23B1 Opening of the switch in the EE system Shut down of the power converter

TE-MPE -EI 23/6/2011,Antonopoulou Evangelia Current of the magnets and their parallel resistance →After the shut down of the power converter, current pass by the parallel resistances of the magnets in order to protect them. →This current has the opposite direction of the current of the circuit. 24

TE-MPE -EI 23/6/2011,Antonopoulou Evangelia Voltage drop across the magnets 25

TE-MPE -EI 23/6/2011,Antonopoulou Evangelia Current in the EE system(1/2) 26

TE-MPE -EI 23/6/2011,Antonopoulou Evangelia Current in the EE system(2/2) 27

TE-MPE -EI 23/6/2011,Antonopoulou Evangelia Voltage in the Dump resistance 28 Simulation: RQS.A23B1 PM_Browser event: _RPMBA.UJ33.RQS.A23B1

TE-MPE -EI 23/6/2011,Antonopoulou Evangelia Electrical Resistance on the magnets 29

TE-MPE -EI 23/6/2011,Antonopoulou Evangelia Electrical Resistance on the magnets 30

TE-MPE -EI 23/6/2011,Antonopoulou Evangelia Temperature of the cable 31

TE-MPE -EI 23/6/2011,Antonopoulou Evangelia Thermal Power dissipated in the magnet due to quench 32

TE-MPE -EI 23/6/2011,Antonopoulou Evangelia Energy dissipated in the magnet due to quench 33

TE-MPE -EI 23/6/2011,Antonopoulou Evangelia Calculation of τ circuit with 2 magnets (RQS.A34B2) 34

TE-MPE -EI 23/6/2011,Antonopoulou Evangelia Calculation of τ circuit with 4 magnets (RQS.A34B2) 35

TE-MPE -EI 23/6/2011,Antonopoulou Evangelia Further steps in due course Investigation of the missing resistance in order to be more accurate in the simulation of the quenches Clarification of the misunderstanding test and comparison of the data of PM_Browser with my simulation 36

TE-MPE -EI 23/6/2011,Antonopoulou Evangelia Thank you for your attention Merci beaucoup pour votre attantion Ευχαριστώ για την προσοχή σας 37