Panasonic is part of a large worldwide groupselling relays and associated switching products under different brand names in different territories.The conditions of use in some territories may differ from those customary in Europe. In particular there are often major differences in regard to national and international specifications, such as UL, CSA, VDE, SEV, EVE, SEMKO, etc. Thus, when considering contact loads as stated in this catalogue (e.g. 10 A, 30 VDC for the SP relay) its hould be understood that these values are not necessarily an absolute maximum but tested ratings. Mostly the stated value has been tested for a certain life expectancy as stated by the manufacturer or the respective test house. Thus, under different conditions, the stated “maximum” may, in practice, be safely exceeded.
W hen 1
W hen 1
W hen 1
Initial failures
Accidental failures
W ear-out failures
65
.
• Different types failures can be
identified the chart. hile zero accidental
failure rate desirable, this actually
not practical the real world.
The eibull probability chart sim pler
alternative com plex calculation
formulas. eibull
distribution expressed the following
equation:
m Figure parameter
a easurem ent parameter
y Position parameter
W eibull distribution can adopted the
actual failure rate distribution the three
variables above are estimated.
(II) Accidental failure period
The initial failure period followed a
long period with low, stable failure rate.Excerpts from Technical Information
5 ife
Safe life inverse degree of
reliability.
• The eibull probability chart easy to
use. Preventive
maintenance effective for this type of
failure.
(III) ear-out failure period
In the final stage the product's service
lifetime comes the wear-out failure
period, which the life the product
expires due ear fatigue. The timing relay's wear-out
failure can predicted with certain
accuracy from the past record uses.
The following describes the correlation
with the bathtub curve. some cases this
represents more practical value of
reliability than MTTF.
[3] FAILURE
1. The value the
figure parameter “m” represents the type
of the failure.
(I) Initial failure period
The high failure rate the initial failure
period derived from latent design
errors, process errors, and many other
causes. ilu ?
Failure defined state system,
equipment, com ponent which part of
all its functions are impaired lost.
The use relay intended only the
accidental failure period, and this period
virtually represents the service lifetime of
the relay. The chart provides the
following advantages:
• The eibull distribution has the closest
proximity the actual lifetime
distribution.
2 e
Product's failure rate throughout its
lifetime depicted bathtub curve, as
shown below. This process called
debugging, performing aging or
screening. In
this period, called accidental failure
period, failures occurs random along
the tim axis. Failure rate high the
beginning and end its service lifetime. Initial failures are screened at
m anufacturer's site through burn-in
process. given value which
makes the following equation true:
1 R(B) %
In general, “B[1 R(B)] 10% more
often used.
3 is
W eibull analysis often used for
classifying product's failure patterns
and determ ine its lifetime
