9

ELECTROLYTIC ALUMINUM CAPACITORS

Revision 09/17

www.exxelia.com

Tel : + 33 (0)2 40 01 26 51

General technical data

r.m.s. value according to current waveform.

6.4.3. Dissipated power versus case dimension

For calculations of ripple currents, considering an internal temperature rise of 10°C

P = ESR.I ²

P = Dissipated power (mW)

( i - a = 10°C)

ESR : Equivalent series resistance (100 Hz 20°C)

I : Ripple current (r.m.s. value at 100 Hz)

For different frequencies from 100 Hz, I must be multiplied by the factor F, according

to above chart. :

6.4.4. Thermal resistance Rth and air cooling

Rth is static thermal resistance (without cooling) between capacitor central hot spot

and ambient temperature measured at a distance of one capacitor diameter

Forced or not cooling air can lead to a significant decrease of these values.

Consequently, r.m.s. ripple current can be increased as a function of air cooling speed :

Ø (mm)

≤ 0,5 m/s

1 m/s

2 m/s

3 m/s

≥ 4 m/s

66 - 90

I~

1,1 I~

1,2 I~

1,25 I~

1,3 I~

36 - 51

I~

1,2 I~

1,4 I~

1,45 I~

1,5 I~

This parameter shall be applied to one capacitor alone.

For capacitors in bank, ambient temperature must be strictly equal around all

capacitors.

6.4.5. Quality guaranty

We guarantee products manufactured during 2 years from the data of shipment

against defaults of material and assembly.

This guaranty can be involved by the buyer only if our products are used within normal

conditions, always according to the state of the art and taking in account storage

conditions.

The equipment design should take into consideration possible failures of our

capacitors and related effects in order to avoid them.

Guaranty is not applicable for damages occurred by surge voltage, irregular use,

polarity inversion or maintenance default.

Guaranty is exclusively limited to the replacement of individual defective capacitors

within the terms of delivery. This rule applied to all cases and particularly to any

further consequence of failures.

6.4.6. Reliability

Failure rate :

FR =

Number of components tested x test duration

Number of failures

Failure rate is measured in FIT (failure in time = 10–9 / hour).

The failure rate is set up during the life time of the capacitor (phase II)

I. Early failure phase (generally excluded during ageing process).

II. Operational life time of the capacitors

III. End of life

Function

Mean value

R.m.s. value

A (t0/T)

A

gt0/T

A (t1/T)

A

g2t1/3T

A/2 (t0/T)

A

gt0/3T

Function

Mean value

R.m.s. value

A /2

A

g3

2A/ (t0/T)

A

gt0/2T

A/2 (t0/T)

A

gt0/3T

Function

Mean value

R.m.s. value

2A/

A /

g2

A /2

A /

g3

0

A