1 PRACTICAL RELIABILITY OF POWER FILTERS IN CRITICAL APPLICATIONS Presented by Will Turner MEng, Senior Design Engineer, MPE Limited, UK EMCUK, Newbury, UK October 2012 ©2012 MPE Limited

2 TOPICS TO BE COVERED Reliability by Design and Manufacture Typical Filter Reliability Data Long Term Field Reliability Data Opportunity Tests Carried Out Test Results Factors Contributing to Filter Reliability Summary

3 RELIABILITY BY DESIGN AND MANUFACTURE Safety margin Materials MTBF predictions Accelerated life testing Test Specifications Controls on build standards High levels of factory testing

4 TYPICAL FIELD SERVICE DATA

5 NEW LONG TERM FIELD DATA MPE recently had the opportunity of providing new filters for upgrading an MOD site which had originally been installed with MPE Power Line Filters as part of an EMP protection system ~20 years Continuous Service Original MPE Filters went through a full inspection & testing process to assess for any degradation or deterioration.

6 DETAILS OF FILTERS REMOVED FROM SITE 42 Power Line Filters removed & tested 10A three phase 15A Single Phase 30A Single line, Single phase and Three phase 60A Single phase and Three phase 100A Three phase High Performance 10kHz to 10GHz

7 VISUAL INSPECTION

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9 ELECTRICAL TESTS CARRIED OUT ON LEGACY FILTERS 100% Tested Proof voltage 2000V dc Capacitance Tan δ Inductance Insulation resistance Discharge resistance Volt drop Sample Tested Insertion loss

10 VOLTAGE PROOF

11 CAPACITANCE AND POWER FACTOR

12 INDUCTANCE

13 INSERTION LOSS

14 VARISTOR TEST RESULTS

15 VARISTOR TEST RESULTS

16 TEST DATA SUMMARY All filters still fully serviceable after 20 years service life. Varistor degradation dependant upon transient exposure –Regular checks or regard as service items

17 SUPPORTIVE CUSTOMER RETURN DATA Analysis of customer returns attributable to MPE relating to last 6200 power line filter shipments over 8 years shows 1 field return for electrical filter reasons (0.016%) Zero returns for voltage dielectric breakdown Zero infant mortality (failures on installation or within first 6 months) Zero field returns out of more than 600 HEMP filters so far supplied (some in service for more than 5 years) Zero field returns from capacitors

18 REASONS CONTRIBUTING TO RELIABILITY Plastic film technology –Self healing capacitors Inception free designs Design safety margins especially on proof volts and temperature rise Design practices Control on in –house capacitor manufacture Controls on production processes and testing

19 SUMMARY Filters can provide reliable long term service with minimal maintenance and minimal performance degradation. Design, manufacturing and testing processes carried out by MPE have proven to be sufficient and appropriate to ensure very high reliability of filters in this environment. –Varistors are service items and should be regularly checked to monitor degradation.

20 THANK YOU ANY QUESTIONS?