Dimensioning Instructions - Bosch L 309 Series Technical Information

7.

Dimensioning instructions

1070 078 131-104 (00.05) GB
Power Supply Module
In principle, the load capacity of thyristors is predetermined by the type allocation to
specified max. welding transformer sizes.
CAUTION!
- The actual load of the thyristor should be checked by the user in each specific
!
case!
For this purpose, the load diagram is used. This load diagram indicates
the effective currents (I
the duty cycle (ED in %) at max.
cooling agent temperature (in _C) and minimum
water throughput (in l/min.).
For determining the percentage duty cycle (ED), the weld time t
time t must be known.
sp
Weld time and weld cycle time
The duty cycle (ED) is calculated as follows:
Example:
CAUTION!
- If there are different weld times and cycle times at one machine, the longest
!
weld time and the shortest cycle time (if necessary, by adding the longest weld
time and the shortest pause time) are to be used for calculating the ED!
Type L 309
RMS
t
s
t
sp
t
s
ED = * 100%
t
sp
In the figure above, the weld time is 2 cycles and
the weld cycle time is 4 cycles.
This results in a duty cycle of ED=50%.
2 cycles
ED = * 100% = 50%
4 cycles
Dimensioning instructions
in A) which the thyristor is capable of
switching as a function of
and the weld cycle
s
15