This document discusses how sustained overvoltage conditions can degrade electronics and reduce product lifetime, even if they are designed to be compatible with overvoltages. It proposes using an accelerated life testing method to quantify the impact. A switch mode power supply circuit will be used as a test device and elevated temperature testing of 160°C will accelerate capacitor aging. The failure criterion will be when capacitor equivalent series resistance increases 2.8 times its initial value. Simulations and statistical analysis will validate the test method and derive relationships between overvoltage, temperature, and failure rate to better understand the thin line between compatible and immune operations.

1. Abstract : Do safe operations ensures operational health as
well? Today appliances are smart enough to protect themselves
from various power quality issues , overvoltage being one of
them. However this doesn’t ensure their reliable operation as
sustaining these overvoltage conditions comes at a cost of
degradation in product life resulting in products reaching failure
earlier than expected. Products are designed to be compatible
with overvoltage's and are not designed to be immune. This study
aims at quantifying this thin line between compatible and
immune operations to study and justify the impact of sustained
overvoltage on product lifetime.
Impact of sustained overvoltage on product lifetime
By : Jitesh Sharma (4936589)
Supervisor – Dr. Phil Cuifo
Subject code: ECTE 953
Date : 22/10/2016
Design of test device: typical front end of most of the
consumer electronics component is the switch mode power
supply (SMPS) which is best suited for testing purpose.
Because of its complexity it can be further simplified to
figure 1 which is common in most SMPS used to power
most of the SMPSs.
Accelerated life testing : It is not at all feasible to test a
capacitor for its entire life, this will requires several
days/weeks of testing. Hence , accelerated testing is
proposed in the presence of elevated temperature of 160
0C which will increase the ageing of capacitor thereby
achieving quick failure required for testing.
Simulation and Analysis: comparing capacitor current
waveforms for two configurations to validate the test device
Statistical Extrapolation
Proposed method of ESR measurement
Sensed capacitor volatge
from test device
Bandpass filter Rectifier Low pass filter
Comparator
Data Channel
Data logging and
monitoring
Oven for applying elevated
temperature
Future Work and Recommendation
Actual testing and derivation of crucial relationships
Economic analysis of the outcome
More research into reliability aspects due to other Power quality
phenomenon i.e. harmonics, voltage sags and swells , iTHD etc.
0%
10%
20%
30%
40%
50%
60%
70%
Electrolytic Capacitors Mosfet Inductive elements Diodes
Distribution of failure for each power component in SMPS
Electrolytic Capacitors
Mosfet
Inductive elements
Diodes
Weakest link (Capacitor)
Motivation : Compatibility VS Immunity…..??????
End of life criteria-Although many parameters like
dielectric strength, change in volume of electrolyte,
Leakage current and dissipation factor contribute to
capacitor degradation but change in ESR has been
considered as the best representative of capacitor
degradation as is evident from research. The
capacitor is said to have achieved its parametric
failure if its ESR increases to 2.8 times its initial ESR.
This has been graphically shown in figure 2 which is
derived using ESR model(1) and Arrhenius life
prediction model(2).
1 . .
……..(1)
T = capacitor operating temperature.
-ESR (t) = the ESR value at time‘t’.
-t = the operating lifetime.
- ESR (0) = initial ESR value at t = 0.
k = constant which depends on the
design and the construction of the
capacitor
L = L0 *2^ (To-T)/10…………(2) where, L
= expected life,
Lo = life at maximum permissible
operating temperature,
T= actual operating temperature,
T0 = rated temperature,
-10
-5
0
5
10
15
25 35 45 55 65 75 85 95 105 115 125 135 145 155 165 175 185 195 205
ESR Increase
Temperature
0
100000
200000
300000
400000
500000
600000
25 45 65 85 105 125 145 165 185 205
ExpectedLife(hrs)
Expected Life vs Temperature
Temperatur
e
Simulation with flyback converter &
test device
Test device simulations with resistive
load
SMPS
Figure 1
Figure 2