EMC test planning
for customers
2 April 2004
EMC Compo 04
Kimball Williams – IEEE President
Introduction
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Objectives of the workshop
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Test objectives
Test system description
Test scheduling
Hardware preparation
Software considerations
Pass / fail criteria
Time frames for preparation
Statistical considerations
Test variations
Records requirements
Running a test
Data reduction and analysis
Reporting the results
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Test Objectives
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Givens:
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Who / Where / When / How / What / Why
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Test Objectives
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Givens:
Customer’s point of view
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Find out what your customer wants
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“Pass” a required test
Validate a design
Correct an EMC ‘problem’
Gather data.
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Test Objectives
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Givens:
Customer’s point of view
Laboratory’s point of view
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Provide accurate test data
Mitigate the design when needed
Conclude the test on schedule
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Test Objectives
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Givens:
Customer’s point of view
Laboratory’s point of view
Mutual agreement:
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Understand the customer’s requirements
Plan to address his major needs
Enlist his help in the required preparation
The test plan can assist in this process
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Test System Description
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EMC lab equipment used for test
Customers equipment
Combined “official test” and
Customer’s equipment – diagram
Justification of ‘modifications’
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Verify EMC lab equipment function
Get customer’s agreement
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Power Input
Power Input
10 uf cap
10 uf cap
LISN
LISN
Unit or
Simulated
Load of
System
Under
Test
Unit or
System
Under
Test
Interconnecting Bundle
15 cm
min.
Touching (no air gap)
15 cm
min.
3 meters
Unsuppressed Relay
Coil, 28 VDC 160 ma.
Test Point A
Polarity
Reversing
Switch
Timer
Supply
Voltage
R
C
28 VDC from
Ungrounded
Source
Example Timing Circuit
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Test scheduling
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Flexibility
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Equipment (calibration / breakage /
otherwise occupied / ….)
Test engineers & technicians (vacations /
illnesses / Dr. appointments / etc. ad
infinitum….
Customer’s equipment (working prototypes
that don’t work / critical components that do
not get delivered / development engineers
that go on vacation / ….
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Test scheduling
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Flexibility
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Communications: Contact between the
customer and test lab is critical
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Hardware Preparation
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EMC laboratory “first systems test”
Development engineers accompany unit
to lab for ‘first’ test
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Initial setup
Working modes
Power and grounding issues
Cables / connectors / adapters
Setup considerations if multiple units are to be
tested
Support hardware
Equipment operation “cycle time”
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Software considerations
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Operational vs test software
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Test “cycle time” implications
Emissions test requirements (scan speed)
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Immunity test implications
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Effects on emissions signature
“Missing” time pulsed emissions
“Fail-safe” or “Limp-home” modes
Special ‘fast recovery’ test software
Concerns about the validity of tests with special
software (hardware / shadowing)
Start this process EARLY!
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Pass / fail criteria
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“Fail?” ! “My product fail?”
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Emissions pass / fail – set?
Design engineers are focused on success
(form/fit/function), not failure
Defining a failure mode is alien and they
may need help
Again…ask this question EARLY
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Time frames for preparation
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As early as possible
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Life after a successful prototype demo
Documents to support testing
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Schematics
parts lists
systems drawings
Software flow charts
ck-lists
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Time frames for preparation
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First discussions – immediately after
tests are scheduled
First “demo” the operation of
equipment (In the EMC lab) –
minimum of one week before tests
Full documentation supporting tests
at a customer / lab staff meeting
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Statistical considerations
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“I want 100% test certainty”
ISO 17025: “…data applies only to
the device tested…”
Measurement uncertainty (A / B / Z)
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Test variations
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Contingency planning
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What to do when things go wrong
Recovery strategies
Back up plans
Brainstorming sessions
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Standard brainstorming methods
Involve your customer
Follow up on ‘most likely’ ideas
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Records requirements
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Normal records
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Test plan
Test records (data sheets) / notebooks / etc
Test matrix (Link to all other records)
Transducer data
Statistical process control records
Abnormal records
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Modified test setup diagrams
Verification tests of modified setups
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Running a test
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Follow the plan!
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Carefully put together the plan
Use its ‘tracking’ features
Deviate only with full knowledge of customer
Hand modifications as needed.
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Changes required
Reference documents
Rational for changes
Customer ‘by-in’
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Data reduction and analysis
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Dealing with the volume of data
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Filing system described in the ‘plan’
Pre-planned locations for everything
Representative data set aside for the ‘report’
File everything else – ‘just in case’
Customer has the ‘right’ to have it all if he
wants it
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Eaton ICDC E3 Laboratory
Conducted RF Emissions
High Frequency
80.0
Limit_1
Limit_2
Limit_3
Limit_4
HF
MF
70.0
60.0
Amplitude
50.0
40.0
30.0
20.0
10.0
0
10.0M
100.0M
1.0G
Frequency
07:40:44 PM, Friday, January 14, 2000
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Reporting the results
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ISO 17025 format
Company requirements
Certification agency requirements
Don’t make it dull!
However, if your management requires
‘dull’ reports – at least put your
excitement into your presentation!
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Thank you!
Questions?
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