Notesale: Turn your study into money

Document Preview

Extracts from the notes are below, to see the PDF you'll receive please use the links above

---

Accelerated Life Test of Capacitor

Index
 Introduction
 Accelerated Life Test Planning
 Acceleration method
 Stress levels
 Stress types
 Sample size
 Censoring time
 Failure definition
 Data collection method and Data analysis
 Conclusion

Introduction:
In today’s world, competition makes product manufacturers to make their
product more reliable and long term use
...
ALT (Accelerated Life Test) is to estimate reliability of
product and to accelerate, shorten the failure times of the product
...
The reliability
of product qualified them by testing at higher stress
...
A
quantitative test is performed during design and development to create
failure as quickly as possible
...

Accelerated Life Test Planning:
To obtain good outcomes from ALT, there should be a reasonable
planning
...
Management consideration consist good team, responsibility
of members
...
Technical
consideration consist analysis method, acceleration method, data
collection, sample unit size, failure definition etc
...

Acceleration method is mainly divided into four types are as below
mentioned:
1
...

3
...


Overstressing
Increasing usage rate
Changing level of control factor
Tightening the failure threshold

 Overstressing:
Overstressing is commonly used acceleration method
...

Such stress consist Electrical as voltage and current which include
constant stress, step stress, progressive stress, cyclic stress and random
stress
...
It can be expressed in
revolutions, cycles, hertz, miles etc
...
For example Capacitors
operate intermittently in circuit and operate continuously in testing
...
Its level is given by design Engineers
...
Control factor affect the life of product
...
Large capacitors are related to Electrical voltage stress to
calculate the life of small capacitors with same design, because larger one
will fail early of larger dielectric area
...

 Tightening the failure threshold:
Failure threshold is performance of product crosses the specified threshold
value
...


Stress Levels:
1
...

3
...

5
...

Step stress:
In step stress, a stress is applied over specified period of time and it is stop
applying
...

Progressive stress:
A stress is applied constantly till specified test plan fail or till predetermined
test time is attained
...

Random stress:
Random stress changes randomly
...

Stress types:
Different product requires different stresses
...
Below are types of stresses
...
Elevated temperature
2
...

4
...

6
...
High
temperature accelerates failure mechanism of products
...

Thermal cyclic:
Thermal cyclic is integral part of environmental stress testing
...
It involves applying high and low
temperature to product over a specified time
...
Absolute humidity
2
...

The ratio of the atmospheric moister present in air to that amount present if
air were saturated is called relative humidity
...

Voltage:
Voltage is the measure of Electrical pressure between two points of an
Electrical circuit
...
Voltage
between two points is measured by connecting Voltmeter between these
two points
...
It is represented by I and is expressed in Ampere
...

Electrical current is used for accelerating stress for Electrical and Electronic
components
...

Mechanical Vibration:
Many products experience vibration in normal use
...
Two types of vibrations are sinusoidal and random
...
So the test should be conduct in sample
...

These samples are to determine control parameters and design
parameters
...
Sample
size affects the test cost, test time, estimate accuracy
...

Censoring time:
In ALT, testing must terminated before all product fail
...
When test resources restricted this method is
used
...

Failure definition:
When manufacture fail to produce products required at consumer level is
called failure
...
Manufacturer may fail to
proper planning of ALT
...
By doing this to reach exact failure time and avoid the
failure of product
...


Data analysis:
It is evaluating test data using analytical and logical reasoning to examine
in test phase
...
Data analysis includes test samples, failure time
...
Environmental characteristics are temperature, humidity,
atmospheric pressure and vibration
...

From above all characteristics and factors temperature is most critical
factor that affects life of capacitors
...
Also save time and money
...
researchgate
...
/224482646_Accelerated_Life_
Testing_of_Capacitors
 http://automotive
...
com/
...
com/
...
B
...
A
...
J
...
(2001), Accelerated Stress
Testing Handbook: Guide for Achieving Quality Products, IEEE
Press, Piscataway, NJ

---