Datasheet

1-5 Reliability

(1)The bathtub curve:

pressure & vibration etc. and mostly affected by temperature factor .

Aluminum electrolytic capacitors feature failure rates shown by the Electrical condition include voltage , ripple current and charge / discharge

following bathtub curve. condition

etc.

1. Temperature & Life

The reduce capacitance & increase DF will be created by the influence

from temperature on the life, such condition mostly caused by a slow

evaporation from the electrolyte to seal position; the electric specificity that is

affected by timing and surrounding temperature as following formula below

and similar to the chemical kinetics of Arrhenius' rule and to be re

uted as the

connection rule of life in electrolytic capacitors.

Eq.1

Lx: Expected Life at Operating Temperature Tx (hour)

a. Initial failure period Lo: Load Life at Maximum Operating Temperature To (hour)

Deficient Capacitors include any products before dispatch that may To: Maximum Operating Temperature ( )

have some deficiency caused by the design, production process or used in Tx:Actual Operating Temperature. ( )

inappropriate environments. B: Accelerate Coefficient of Temperature( 2)

b. Random failure period From the Eq.1 , it means about double acceleration for temperature

The capacitors have a low defect ratio in the period after it has been raising at 10 C . Therefore , it comes a longer working life once a

stabilized. temperature setting lower than Tx while products design .

c. Wear out failure period

The performance of capacitors will decrease with an increase in usage

period. The malfunction rate may vary due to the structural design.

(2) Failure types: (See Table-1)

a). Completely malfunction:

Capacitor is completely disabled to all functions, e.g.: short circuit,

open circuit.

b). Malfunction cause by wear and tear gradual malfunctioning of the

capacitor, the cause of the malfunction would depend on the

environmental conditions.

1-6 Life of the Electrolytic Capacitors

2. Rated Voltage and Life

A effects by using condition for the life of electrolytic capacitors which

While working , the voltage under the input of rated voltage and for the

environmental condition & electrical condition .

reducing of volt age, although with little or more influence to electrolytic

Environmental condition include temperature , humidity , atmospheric

capacitors but, no necessary for special concern after compare with the

influence by temperature.

Fig.1-15 Bathtub curve

Table-1 Failure modes and causes