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Poor Power Quality as an EMI Problem M. McClelland Anteon Corporation 1 SEA 53H3--VIN/PEL-04 (As of 17 Oct 01) What is Power Quality (PQ)? • Power Quality is “The concept of powering and grounding electronic equipment in a manner that is suitable to the operation of that equipment and compatible with the premise wiring system and other connected equipment.” © IEEE Recommended Practice for Powering and Grounding Sensitive Electronic Equipment IEEE Std 1100-1999 2 SEA 53H3--VIN/PEL-04 (As of 17 Oct 01) How is Poor PQ an EMI Problem? • EMI is: “Any electromagnetic disturbance which interrupts, obstructs, or otherwise degrades or limits the effective performance of electronics/electrical equipment. It can be induced intentionally, as in some forms of electronic warfare, or unintentionally, as a result of spurious emissions and responses, intermodulation products, and the like.” Federal Telecommunication Standard 1037 • Failure to power and ground electronic systems in a manner suitable to the operation of that equipment results in poor PQ. – Poor PQ in turn may result in EMI related issues which may cause system data disruption, hardware stress, and hardware destruction*. *IEEE Std. 1100-1999 - 4.6.5 3 SEA 53H3--VIN/PEL-04 (As of 17 Oct 01) Where to find PQ events ? • Typical Frequency Spectrum – PQ refers to conducted energy, both normal and common-mode occurring within the VLF through VHF bands, 30 HZ through 200 MHz – May also be radiated energy ° < 50 kV/m, < 200 kHz ° < 1.5 kV/m, > 200 kHz • PQ anomalies, because of the higher voltages and currents available, can instantly destroy valuable electronic equipment. 4 SEA 53H3--VIN/PEL-04 (As of 17 Oct 01) Doesn’t MIL-STD-461 Cover PQ Effects? • YES & NO (Examples) – Yes - Radiated transients – No - Conducted Transients - manual switching* • MIL-STD-1399 Interface Standard for Shipboard Systems, Section 300A, Electric Power, Alternating Current covers some transient requirements and some grounding requirements. • MIL-STD-464 Electromagnetic Environmental Effects Requirements for Systems addresses radiated emissions > 10 kHz. • * MIL-STD-461E Append. A-40.2.65 SEA 53H3--VIN/PEL-04 (As of 17 Oct 01) Sample Manual Switching Transient(s) 3 Phase V 1052.3 V23 25.7 -487.6 -1001.0 Zoomed 0.00000 0.02013 0.04026 0.06039 0.08052 V12 Volts V31 539.0 0.10064 Seconds DDG-82 Mk. 41 Aft VLS Power On Cycle 6 SEA 53H3--VIN/PEL-04 (As of 17 Oct 01) Navy Power Quality Indicators • Combatants - DDG-51 Class (DDG-51-DDG78): 339 unexplained power supply failures 19922001 – 181 failures on Mk 41 VLS alone • Aviation - New Automatic Test Equipment CASS - hardware failures at five sites, FY 97-FY 01 $14,851,298 – Includes material costs only. 7 SEA 53H3--VIN/PEL-04 (As of 17 Oct 01) PQ Sources of Concern “The Navy Today” • Sensitive electronic loads returning noise, harmonics, and switching transients back into the facility power source, via the power and grounding leads, degrading the source power and grounding system. – Internal induced damage or degradation to systems and components. • Legacy power distribution systems do not support 21st century sensor/weapons systems – Electronics revolution requires a “better” power quality solution 8 SEA 53H3--VIN/PEL-04 (As of 17 Oct 01) PQ Sources of Concern • Platform/Facility power source anomalies conducted by the power and grounding leads resulting in equipment degradation and failures. - Externally induced damage or degradation 9 SEA 53H3--VIN/PEL-04 (As of 17 Oct 01) PQ/EMI Classifications * • Type I, Signal-Data Disruption • Type II, Gradual Hardware Stress and Latent Failures • Type III, Immediate Hardware Destruction *IEEE Std. 1100-1999 10 SEA 53H3--VIN/PEL-04 (As of 17 Oct 01) Type I - Signal-Data Disruption • Digital Signal Circuits susceptible to voltage surge interference via: – Conduction – Inductive and Capacitive coupling – Electromagnetic radiation • “1” & “0” Logic State is relatively stable, when latched. • If interference is coincident with state transition… then a 50/50% chance of error can result. “Lock up”of a CPU due to a forced “truth table” violation is possible. • TT violation can exceed junction operating temperatures. • Erratic state transitions often blamed on bad software/hardware 11 SEA 53H3--VIN/PEL-04 (As of 17 Oct 01) Type I - Signal-Data Disruption (cont’d) • Surge Paths can be: – Line Filters ° Low Pass LC network filters with line-to-ground (chassis) shunt elements. Shunt capacitors are restricted to <0.1 uF by MIL-STD461E - 4.2.2, and MIL-STD-1399-300 - 5.2.4. ° This requirement is seldom enforced ! – Metal Oxide Varistor (MOV) based Transient Voltage Surge Suppressors (TVSS) configured in shunt mode (line-chassis) ° > VON, Supply phase is connected to chassis. ° This appears to conflict with intent MIL-STD-461E - 4.2.2 12 SEA 53H3--VIN/PEL-04 (As of 17 Oct 01) Type II - Gradual Hardware Stress/Latent Failures • Repeated Truth Table violations caused by voltage surges (Voltage Overstress- EOS) can weaken chip substrate due to thermal overstress - breaks down insulating oxides. • 2.5 VDC Logic family, oxide layers break down at 5 VDC. • DC Current stress can cause accelerate substrate Electromigration, the formation of metal voids in interconnects Intel Technology Journal Q3’98 13 SEA 53H3--VIN/PEL-04 (As of 17 Oct 01) Type III - Immediate Hardware Destruction • Voltage/Current overstress can cause immediate, noticeable problems • This MOV rated 40kA @ 6/20 uSec • Power Distribution components are tougher than CPU chips Failed MOV - USM-636 Internal TVSS shunt element 14 SEA 53H3--VIN/PEL-04 (As of 17 Oct 01) Type III - Immediate Hardware Destruction Thresholds of failure of selected semiconductors Semiconductor type Disruption energy (J) Destruction energy (J) Digital Integrated circuits 10-9 10-6 Analog integrated circuits 10-8 10-6 Low-noise transistors 10-7 10-6 High-speed transistors and ICs 10-6 10-5 from IEEE Std 1100-1999 Table 4-6 • Common-mode shunt elements can direct couple large energy transients into system chassis - possibly causing Type I, II, or III damage 15 SEA 53H3--VIN/PEL-04 (As of 17 Oct 01) Military Application Areas of Power Quality • Warships • Support Ships • Aircraft • Aircraft Maintenance Depots • Ground Force Tactical Shelters • Shore Support Facilities Typical Power Quality Analysis Software 16 SEA 53H3--VIN/PEL-04 (As of 17 Oct 01) Conclusion • Poor PQ can degrade system/unit reliability and maintainability. • New technology and old infrastructure fuel the need for new thinking and technology in power system engineering • PQ solutions have immediate benefits: – Operational reliability improves – System Operator confidence improves – Maintenance & damage costs are reduced 17 SEA 53H3--VIN/PEL-04 (As of 17 Oct 01) ANY QUESTIONS? ? 18 SEA 53H3--VIN/PEL-04 (As of 17 Oct 01)