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Preliminary conducted noise test results for LV power supplies. Bruno Allongue CERN-PH-ESS Fernando Arteche Imperial College – CERN 21 January 2005. Outline. 1. Introduction 2. Set-up Description Set-up limitation 3. Measurements CAEN A3009 Wiener – Maraton Wiener – PL8F12
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Preliminary conducted noise test results for LV power supplies Bruno Allongue CERN-PH-ESS Fernando Arteche Imperial College – CERN 21 January 2005
Outline • 1. Introduction • 2. Set-up • Description • Set-up limitation • 3. Measurements • CAEN A3009 • Wiener – Maraton • Wiener – PL8F12 • 4. Conclusions
1. Introduction • DC Power distribution often used in HEP • AC-DC Conversion • DC-DC Conversion Periphery of the detector • Front End Electronics • Characteristics of DC-DC converters • High efficiency • Galvanic insulation (Input and Output) • High EMI emissions • Emissions – Conducted or Radiated • EMI emission might couple to the FEE • Cause a malfunction
1. Introduction • Two kinds of EMI emissions • Radiated Emissions • Conducted Emissions - TEST • Conducted emissions – Propagation • Common Mode • Differential Mode Conductive Noise Conductive Noise Distribution Bus FEE PS Radiation Noise FEE PS Conductive Noise Conductive Noise
2. EMC test Set-up • The test is focused on the output of the PS units (DC-output) • CM & (CM+DM) output emissions • The test result is compared with standard input levels - Only as a reference • A resistance is used as a load • Electronic loads are noisy • Output power is limited • Cable shields are used as return path for CM currents • They are connected to ground on one side & the other side through a capacitor • Equipment • Spectrum Analyzer (Rohde&Schwarz) – Peak mode • Current probe – ETS 91550-1
Icm Icm - - out out Iin Iin PS PS Icm Icm - - in in Iout Iout Cs = 0.5 Cs = 0.5 μF μ Cs = 0.1 Cs = 0.1 μ μ F F PS PS - - DUT DUT Cs = 0.1 Cs = 0.1 μ μ F F 2. EMC test - Set-up Icm - out Iin PS Cload Cload = 1 = 1 μ μF Icm - in Iout Cs = 0.5 μ Cs = 0.1 μ F PS - DUT Cs = 0.1 μ F
3. EMC test - CAEN A3009 • Iout = 8 A – Vout = 5 V (90 % channel)
3. EMC test – Wiener Maraton • Iout = 8 A – Vout = 5 V (8 % channel)
3. EMC test – Wiener PL8F12 • Iout = 8 A – Vout = 12 V (35 % channel)
4. Conclusions • This test is preliminary • The aim was to compare the conducted emissions of 3 different switching power supplies operating with the same output load • This test is not complete and contains limitations • Wiener PS are not fully loaded • Nevertheless common mode noise is present in all PS units at the output • Additional tests should be performed