Technical information

Notes on Rating
3-1
1070 080 059-101 (2001.04) GB
3 Notes on Rating
The load capability of an MF inverter is always predefined by the type desig-
nation indicating the specific maximum welding transformer rating.
CAUTION
Overloading may cause damage to the MF inverter!
Always check the actual load applied on the MF inverter! Any and all
warranty excluded in case of damage caused by overload.
To check the actual load, use the load diagram. It shows the
D output currents (I
PRIM
in A) relative to
D the duty cycle (ED in %) at
D maximum ambient temperature (in °C)
that can be switched by the PSI 6000 MF inverter.
The weld time t
s
and the overall weld cycle duration t
sp
must be known to
determine the duty cycle.
t
sp
t
s
Weld time and overall weld cycle duration
The duty cycle is computed as follows:
ED =
t
s
t
sp
* 100%
Example:
ED =
4 ms
8 ms
In the graph shown above, the weld time is 4 ms and
the weld cycle duration is 8 ms.
This results in a duty cycle ED = 50%.
• 100% = 50%
. Note: If different weld times or overall weld cycle times occur on a
machine, the longest weld time and the shortest overall weld cycle
time (to be determined, if required, by adding the longest weld time to
the shortest cool time) must be used for calculating the duty cycle!
When you have calculated the duty cycle, you can use load diagrams to
verify the proper selection of the MF inverter.