SEA 53H3--VIN/PEL-04 (As of 17 Oct 01) 1 Poor Power Quality as an EMI Problem M. McClelland Anteon Corporation

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

Poor Power Quality as an EMI Problem

M. McClelland Anteon Corporation

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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

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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

Seconds

Vo

lts

0.00000 0.100640.02013 0.04026 0.06039 0.08052 -1001.0

1052.3

539.0

25.7

-487.6

V1

2V

23

V3

1

Zoomed

DDG-82 Mk. 41 Aft VLS Power On Cycle

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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”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

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PQ Sources of ConcernPQ 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

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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

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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

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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)

° > VON, Supply phase is connected to chassis.

° This appears to conflict with intent MIL-STD-461E - 4.2.2

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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

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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

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Type III - Immediate Hardware Destruction

• Common-mode shunt elements can direct couple large energy transients into system chassis - possibly causing Type I, II, or III

damage

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

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Military Application Areas of Power Quality

• Warships

• Support Ships

• Aircraft

• Aircraft Maintenance Depots

• Ground Force Tactical Shelters

• Shore Support FacilitiesTypical Power Quality Analysis Software

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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

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ANY QUESTIONS?

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SEA 53H3--VIN/PEL-04 (As of 17 Oct 01) 1 Poor Power Quality as an EMI Problem M. McClelland Anteon Corporation