The Reliable Power Supply – an Oxymoron?

Can a power supply actually be reliable? Is there such a thing as a Million Hour Power

Supply? Can you just specify the reliability and get it? Picking a good supplier is important, but is it

enough? How about MTBF calcs? --stress analysis?

–---What kind of testing?

In Search of Dependable Power

Pick a good supplier Specify the important stuff Trust but Verify Measure Field performance

You want a Good Power Supply?

No matter whether OEM or Custom:

Check out your supplier!

Important Specifications

Field MTBF Life Expectancy Require Failure Analysis of returned units MTBF Calculation?

Supplier check list

– ISO certification; Quality Manual

– Design (review and test)– Manufacturing (FA and CA process)– Material control (AVL)– Effective QUALITY Management– Reliability reporting and feedback

Stick to New Technology

Picking a good Supplier

You’re going to have problems: make sure you pick one that you can deal with– Accessibility of responsible personnel– Receptive attitude– Dialog

Make sure he understands that “Failure Analysis” is not the same as “Repair”

Proof of the Pudding

Don’t expect the Field to take care of itself– Real-time field tracking exposes problems as they

happen Design problems Revision incompatibility Customer specific Supplier process problems

Field Data Tracking

FACTORY CONTROL SYSTEM

INSTALLED SYSTEMS CONFIGURATION

DATABASE

FIELD SERVICE ACTIONS

DATABASE

HP NonStop Tracking Databases

How Good is Good?

Range from 300,000 to 1.6 Million hoursActual

Pwr Supply Watts Outputs Spec Field MTBFA1 750 5 1,000,000 1,500,000A2 750 5 1,000,000 300,000B1 1500 1 1,500,000 1,752,000B2 1500 1 1,500,000 584,000

D1.1 1200 1 1,500,000 324,444D1.2 1200 1 1,500,000 547,500D2 1200 1 1,500,000 673,846E1 276 1 1,000,000 1,135,000E2 276 1 1,000,000 1,135,000F1 460 1 750,000 585,000F2 460 1 750,000 585,000

Two Vendors, Same PS

One year’s Field Data3-month rolling average

1,464,570

314,755

0

500,000

1,000,000

1,500,000

2,000,000

2,500,000

Apr

May Jun

Jul

Aug Sep Oct

Nov

Dec Jan

Feb

Mar

Apr

May

MT

BF

(H

rs)

Vendor B

Vendor A

Early Wearout

Weibull Hazard Plot for System Power Supply

Slope = 1

0.01%

0.10%

1.00%

10.00%

100.00%

1 10 100 1000 10000 100000

Time to Replacement Since First Customer Ship

Cu

mu

lati

ve

Ha

zard

Slope > 1 : Increasing Failure RateSlope = 1 : Constant Failure RateSlope < 1 : Decreasing Failure Rate

(Hours)

Wearout began at ~2 years

Tales from the Crypt

AVL Control Customer environment Fan Selection Design problem Board layout Manufacturing process

Conclusion: In Search of Dependable Power

Pick a good supplier Specify the important stuff Trust but Verify Measure Field performance