ALC10C331ED450 BHC COMPONENTS, ALC10C331ED450 Datasheet - Page 15

• Manufacturer Part Number: ALC10C331ED450
• Description: CAPACITOR, 330UF 450V CAPACITOR, 330UF 450V
• Manufacturer: BHC COMPONENTS
• Series: ALC10r

Specifications of ALC10C331ED450

• Capacitance: 330UF
• Voltage Rating, Dc: 450V
• Capacitor Dielectric Type: ALUMINIUM ELECTROLYTIC
• Temp, Op. Max: 85(DEGREE C)
• Temp, Op. Min: -40(DEGREE C)
• Tolerance,: 20%
• Rohs Compliant: YES

mounting method, which is at a higher temperature than the
ambient air. Under steady state conditions, when thermal
equilibrium has been reached, the heat generated will be
exactly balanced by the heat loss.
If we consider only the loss of heat generated within the
capacitor, and ignore heat absorbed from surrounding
components and through the mounting arrangement, we
arrive at the simplified thermal equivalent circuit shown
below.
Thermal resistance factors:
Rhc = Hot-spot to can
Rca = Can to ambient air
Rbp = Can base to mounting plate
Rpa = Mounting plate to ambient air
Total thermal resistance from hot-spot to ambient air is
given by:
Rha = Rhc + 1/(1/Rca + 1/(Rbp + Rpa))
measured in °C/W
In each case the thermal resistance factors shown are
effectively a lumped combination of conduction, convection
and radiation.
The method of construction, standard or extended cathode,
will determine the Rhc value. The values of Rca and Rpa
will vary according to the level of airflow, if any. The value
of Rbp will depend upon the characteristics of the material
placed between the aluminium base of the can and the
mounting plate (i.e. insulating end discs and/or thermal
pads) and also on the pressure holding the capacitor against
the mounting plate.
BHC have carried out extensive testing to establish the
thermal resistance of the hot-spot to ambient, Rha, for each
case size across each range. From this data, life expectancy
can be calculated for both standard and special designs
under most operating conditions.
Ambient temp
Core temp
Can temp
Rhc
Rca
Rbp
Rpa
A full technical article, TD003, is included in “Aluminium
Electrolytic Capacitors - Application Notes”, available
from BHC, which explains life expectancy and thermal
characteristics in more detail. Included in the article is
an explanation of how to calculate life expectancy by the
end user.
Life Expectancy and Rated Ripple Current
When ripple current is applied to a capacitor the most
important parameter in relation to the life expectancy is the
esr. The value of esr will slowly increase throughout the life
of the capacitor, leading to a gradual increase in power loss
and hence core temperature rise.
Long term endurance testing, with voltage and ripple
current applied, has established the characteristic
parameter changes which are displayed by each product
family. The typical esr characteristic is shown below:
Careful study of these curves has enabled the development
of a mathematical model to simulate the changes in esr
which occur under various test conditions and level of stress.
The results of these mathematical models is included in a
full technical article, TD004, in “Aluminium Electrolytic
Capacitors - Application Notes”, available from BHC. The
article includes graphs for most products which allow life
expectancy to be extrapolated, based on rated ripple
current and ambient air temperature.
ESR
Increase
Life Expectancy
Life
13