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

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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.

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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-40.2.6

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Sample Manual Switching Transient(s)

3 Phase V 1052.3

539.0

25.7

-487.6

-1001.0

0.00000

0.02013

0.04026

0.06039

Seconds DDG-82 Mk. 41 Aft VLS Power On Cycle 0.08052

Zoomed 0.10064

6 SEA 53H3--VIN/PEL-04 (As of 17 Oct 01)

Navy Power Quality Indicators

•

Combatants -

DDG-51 Class (DDG-51-DDG 78): 339 unexplained power supply failures 1992 2001 – 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.

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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-STD 461E - 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) ° >

V ON , 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 Digital Integrated circuits Analog integrated circuits Low-noise transistors High-speed transistors and ICs Disruption energy (J) Destruction energy (J) 10 -9 10 -6 10 -8 10 -7 10 -6 10 10 10 -6 -6 -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)