Application constraints

AN3432

18/24

Doc ID 019041 Rev 1

3.2

Constraints linked with reliability test

3.2.1

Thermal test

This test is defined in EN61215 and in DIN V VDE V 0126-5:2008 in two steps as described

in Figure 14.

Figure 14.

Thermal test synopsis

Using Equation 17 and Equation 18 it is possible to evaluate if the requirements of EN61215

can be met.

Equation 17

then the maximum forward voltage is

Equation 18

Incoming measurements

Measure V ,I ,V at

25 °C on by pass

diode

FR

R

Test junction box

@75 °C 1 hour,

I= I

d

sc

T>Tmax

jj

Failed ! The

junction box is

not qualified

T<Tmax

jj

Test junction box @75 °C

1hour, I =1.25 x I

dsc

Start

step 2

T>Tmax

jj

Failed ! The junction

box is not qualified

Diode still functions as a diode

compared with incoming

measurements

SUCCESS! JUNCTION BOX

MEETS THE REQUIREMENTS

T<Tmax

jj

Diode does

no function or

visual defect

Failed! The

junction box is

not qualified

Step 1

Step 2

I

sc

1.25 x I

sc

T

(

P

j

cond

sc

j

sc

F

I

)·

T

,

I

(1.25 ·

·1.25

V

)

=

j

cond

) =

T

(

P

(Tjmax - 75 °C)

Rth(j-a)

max

j

) <

T

sc

sc

F

·

,

I

(1.25 ·

V

(Tjmax - 75 °C)

Rth(j-a)

max

max

1

1.25 · I