Datasheet

16© KEMET Electronics Corporation • KEMET Tower • One East Broward Boulevard A4006_ESC • 4/22/2019
Fort Lauderdale, FL 33301 USA • 954-766-2800 • www.kemet.com
Single-Ended Aluminum Electrolytic Capacitors – ESC, +105°C
Leakage Current (LC) cont’d
Astheoxidelayerisregeneratedinuse,theleakagecurrentwill
gradually decrease to its normal level.
The relationship between the leakage current and voltage applied
at constant temperature can be shown schematically as follows:
Where:
V
F
= Forming voltage
Ifthislevelisexceeded,alargequantityofheatandgaswillbe
generated and the capacitor could be damaged.
V
R
= Rated voltage
This level represents the top of the linear part of the curve.
V
S
= Surge voltage
This lies between V
R
and V
F
. The capacitor can be subjected to V
S
for short periods only.
Electrolytic capacitors are subjected to a reforming process before acceptance testing. The purpose of this preconditioning
is to ensure that the same initial conditions are maintained when comparing different products.
Ripple Current (RC)
Themaximumripplecurrentvaluedependson:
• Ambient temperature
• Surface area of the capacitor (heat dissipation area)
tanδorESR
• Frequency
The capacitor’s life depends on the thermal stress.
Frequency Dependence of the Ripple Current
ESRand,thus,thetanδdependonthefrequencyoftheappliedvoltage.Thisindicatesthattheallowedripplecurrentisalso
a function of the frequency.
Temperature Dependence of the Ripple Current
Thedatasheetspeciesmaximumripplecurrentattheuppercategorytemperatureforeachcapacitor.
Expected Life Calculation
Expectedlifedependsonoperatingtemperatureaccording
tothefollowingformula:L=Lox2
(To-T)/10
Where:
L: Expectedlife
Lo: Loadlifeatamaximumpermissibleoperating
temperature
T: Actual operating temperature
To: Maximumpermissibleoperatingtemperature
This formula is applicable between 40°C and To.
I
V
R
V
F
V
V
S
Actual Operating Temperature (C°)
Expected Life Calculation Chart
Expected life (h)