IEEE 386 Switching Tests

Fall ICC 2017

Nigel Hampton, Josh Perkel

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Efficient Switching Tests

for IEEE 386

Substantiation Testing

IEEE 386 Switching Tests

Fall ICC 2017

Outline

Characterize current

performance on switching

Determine acceptable

compromises

• Knowledge

• Certainty

Use parameters from current

performance to develop

reduced shot burden test

protocol

IEEE 386 Switching Tests

Fall ICC 2017

Data

given in

386

reports

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Combination D Combination S

1 - 15 16-30 1 - 15 16-30

Pass 10 shots Not pass 10 shots 9

Pass 10 shots 1 10

Pass 10 shots 2 3

Pass 10 shots 3

Pass 10 shots 4

Pass 10 shots 5

Not pass 10 shots 6 8

Pass 10 shots 7 1

Pass 10 shots 8 2

Pass 10 shots 9 3

Pass 10 shots 10 4 9

Pass 10 shots 5

Pass 10 shots 6

Pass 10 shots 7

Pass 10 shots 8

IEEE 386 Switching Tests

Fall ICC 2017

The goal of this presentation

is not to give you the answer

The goal is to show how to

get to the answer and what it

might look like

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IEEE 386 Switching Tests

Fall ICC 2017

Approach

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Collated data from 15 different tests

All tests reported a pass !

Results are solutions in the market

Some tests reported the shot of failure

Some tests did not report shot of failure

Overall

High Limit 93%

Success Rate: 90% indiv combinationsLow Limit 87%

IEEE 386 Switching Tests

Fall ICC 2017

Philosophical Bit

• How do we see the Switching Test?

• Are the elbows in the switching test like legos?

• The switching shots don’t impact things

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IEEE 386 Switching Tests

Fall ICC 2017

Philosophical Bit

• How do we see the Switching Test?

• Do the elbows each degrade a bit differently on each

shot such that it is progressively harder to pass as each

shot is applied?

• Is it an ageing test?

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Shots

Capabili

ty

IEEE 386 Switching Tests

Fall ICC 2017

Recall collated data from

15 “real tests”

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IEEE 386 Switching Tests

Fall ICC 2017

Overview of Collated Data

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42 Fails

19 shot known

390 Passes

Shots

IEEE 386 Switching Tests

Fall ICC 2017

Estimate of Current Elbow Performance

10

Shots

IEEE 386 Switching Tests

Fall ICC 2017

Critical Elbow Performance Marker

11

30 Shots

Shots

IEEE 386 Switching Tests

Fall ICC 2017

Compromise

• What do you need to consider giving up to gain

efficiencies, what are our tools to do this?

• Knowledge of Performance – exactly how good

something is

• Certainty in the results

• Number of Samples

• Number of Shots

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Goal is reduction of the

Shot Burden

Current Shot Budget is

300

IEEE 386 Switching Tests

Fall ICC 2017

Substantiation Proposition

If X new units successfully complete Y shots, then we can

be Z% certain that the new units are as good or better than

the historical references (a & b - - 30 shots and 1.4 in this example)

If we do this, X * Y will be lower than the “product for

reference cases” (300) for the same Z

However, as there will be no failures, it will not be possible

to determine how good the new units are

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IEEE 386 Switching Tests

Fall ICC 2017

Recall Elbow Performance

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30 Cycles

Shots

IEEE 386 Switching Tests

Fall ICC 2017

How many Passing Elbows are required

1 − 𝐶𝑜𝑛𝑓𝑖𝑑𝑒𝑛𝑐𝑒

= 𝑒− ൗ

𝑆ℎ𝑜𝑡 𝑇𝑎𝑟𝑔𝑒𝑡𝐶𝑟𝑖𝑡𝑖𝑐𝑎𝑙 𝑆ℎ𝑜𝑡

𝛽 𝑛0

• b and Critical Shot are set by the prior

performance we established – 1.4 & 30

• Can adjust Confidence, Shot Target & n0

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IEEE 386 Switching Tests

Fall ICC 2017

Accept better than a certain level

90% certain

Zero Fails

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10 shots

10/30 =0.33

15 shots

15/30 =0.5

11 samples

10 shots

0 fails

6 samples

15 shots

0 fails

IEEE 386 Switching Tests

Fall ICC 2017

Accept better than a certain level

90% certain – alternative performance

Zero Fails

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10 shots

10/30 =0.33

10 shots

10/20 =0.5

9 samples

10 shots

0 fails

5 samples

10 shots

0 fails

IEEE 386 Switching Tests

Fall ICC 2017

Impact of Confidence

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Shots

Sequence

IEEE 386 Switching Tests

Fall ICC 2017

How many Passing Elbows are required

when one fails

1 − 𝐶𝑜𝑛𝑓𝑖𝑑𝑒𝑛𝑐𝑒 = 𝑒− 𝑅𝛽 𝑛1

+ 𝑛1(1 − 𝑒− 𝑅𝛽) 𝑒− 𝑅

𝛽 𝑛1−1

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IEEE 386 Switching Tests

Fall ICC 2017

Accept better than a certain level

90% certain

One Fail

20

10 shots

10/30 = 0.33

15 shots

15/30 = 0.5

19 samples

10 shots

1 fail

11 samples

15 shots

1 fail

IEEE 386 Switching Tests

Fall ICC 2017

To be 90% certain that the device is as

good as or better than the reference

• 6 passes in a row to 15 shots: burden 90 shots 30%

Or

• 11 passes in a row to 10 shots: burden 110 shots 37%

Or

• 10 passes and 1 fail to 15 shots: burden 165 shots 55%

Or

• 18 passes and 1 fail to 10 shots: burden 190 shots 64%

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IEEE 386 Switching Tests

Fall ICC 2017 22

Combination D Combination S Combination N

1 - 15 16-30 1 - 15 16-30 1 - 15 16-30

1 15S 1 10S 15 10S 1 10S 15 10S

2 15S 2 10S 16 10S 2 10S 16 10S

3 15S 3 10S 17 10 S 3 10S 17 10 S

4 15S 4 10S 18 10 S 4 10S 18 10 S

5 15 S 5 10S 5 10S

6 15S 6 10S 6 10S

8 7 10S

7 10S 8 10S

8 10S 9 10S

9 10S 5

10 10S 10 10S

11 10S 11 10S

12 10S 12 10S

13 10S 13 10S

14 10S 14 10S

IEEE 386 Switching Tests

Fall ICC 2017

Conclusions

• Can use existing knowledge to reduce the shot burden

• Approach is statistically rigorous & used in other

industries

• Based on quantifiable experimental data

• Decisions are transparent, thereby making updating

straightforward

• Need cooperation within the industry to make the dataset

relevant

– Test Reports

– Identified Shots failing (or shot range)

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IEEE 386 Switching Tests

Fall ICC 2017

More Information

• The New Weibull Handbook – Bob Abernethy

• IEEE Guide for the Statistical Analysis of Electrical

Breakdown Data – Fothergill, Montanari, Hampton,

Ross, Stone

• Statistical Treatment of Fatigue Experiments – Leonard

Johnson

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