1. PACS IIDR 01/02 Mar 2001 PACS Grounding Scheme and EMC1 Grounding Scheme and EMC Matthias Rumitz, MPE

2. PACS IIDR 01/02 Mar 2001 PACS Grounding Scheme and EMC2 Overview System Diagram Grounding / EMC Concept Mechanism Grounding Concept Detector Grounding Concept Example: MEC Grounding Grounding / EMC Status

3. PACS IIDR 01/02 Mar 2001 PACS Grounding Scheme and EMC3 System Diagram SPU MEC DEC BOLC FPU BOLA CDMU OBC LCL DPUS/C Bolos CREs Grating Filters Temp. Sensors Chopper Black Bodies

4. PACS IIDR 01/02 Mar 2001 PACS Grounding Scheme and EMC4 Grounding / EMC Concept Requirements of IID-A (5.10 & 5.14) implemented “Distributed Single Point Grounding” DPU, SPU, MEC: secondary ground connected to S/C Additional EMC measures (DEC, BOLC): Isolation between primary and secondary power Reduced slope of DC/DC transformer EMI filter at DC/DC secondary side

5. PACS IIDR 01/02 Mar 2001 PACS Grounding Scheme and EMC5 Mechanism Grounding Concept FPU (i.e. mechanisms): electrically connected to S/C = reference ground Drive circuits: differential supply voltages Sensors: differential read-out => no ground loops, EMI risk minimized

6. PACS IIDR 01/02 Mar 2001 PACS Grounding Scheme and EMC6 Detector Grounding Concept FPU (i.e. detector-housing): electrically connected to S/C => reference ground Warm Electronics (DEC1, DEC2, BOLC): secondary ground can be connected to S/C Detectors (CREs, bolometers): analog ground can be connected to FPU (= S/C) => reference ground: either Detectors or Warm Electronics

7. PACS IIDR 01/02 Mar 2001 PACS Grounding Scheme and EMC7 Example: MEC Grounding Outer shield connected to boxes via backshells Power supplies: DPU, SPU, MEC, BOLC Warm Interconnecting Harness shorter than 1m Grounding: DPU, SPU, MEC: local BOLC, DEC: local / FPU

8. PACS IIDR 01/02 Mar 2001 PACS Grounding Scheme and EMC8 Grounding / EMC Status

9. PACS IIDR 01/02 Mar 2001 PACS Grounding Scheme and EMC9

10. PACS IIDR 01/02 Mar 2001 PACS Grounding Scheme and EMC10 Redundancy Concept

11. PACS IIDR 01/02 Mar 2001 PACS Grounding Scheme and EMC11 Purpose of Template Create uniform set of presentations Allow easy re-use of parts of presentations on other occasions (e.g. status report at FIRST/Herschel Science Team meetings)

12. PACS IIDR 01/02 Mar 2001 PACS Grounding Scheme and EMC12 DPU Grounding

13. PACS IIDR 01/02 Mar 2001 PACS Grounding Scheme and EMC13 SPU Grounding