EMI Issue List

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Transcript EMI Issue List

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)
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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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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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.
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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
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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.
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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
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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
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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
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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
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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
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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
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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
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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
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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
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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
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SEA 53H3--VIN/PEL-04 (As of 17 Oct 01)
ANY QUESTIONS?
?
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