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© KEMET Electronics Corporation • P.O. Box 5928 • Greenville, SC 29606 • 864-963-6300 • www.kemet.com

V0001_VA • 10/25/2016

Surface Mount Varistors

VA Series Automotive Grade 125°C

Reliability

In general, reliability is the ability of a component to perform and maintain its functions in routine circumstances, as well as

hostile or unexpected circumstances. The mean life of series components is a function of:

• Factor of Applied Voltage

• Ambient temperature

Mean life is closely related to Failure rate (formula).

Mean life (ML) is the arithmetic mean (average) time to failure of a component.

Failure rate is the frequency with which an engineered system or component fails, expressed for example in failures per

hour. Failure rate is usually time dependent, an intuitive corollary is that the rate changes over time versus the expected

life cycle of a system.

Failure rate formula – calculation

Λ=

[fit]

ML[h]

FAV – Factor of Applied Voltage

Λ=

Vapl

V

max

Vapl = applied voltage

V

Years

Mean Life on Arrhenius model

1,000

100

10

1

h

120 100 80

60

40

20

°C

FAV

0,7

0,8

0,9

1,0