In North America the power grid is 60 hertz. All schedules and operations are based upon that power. In other parts of the world power is generated at other power levels. Many use 50 hertz. If one has a good weld schedule in a 60 hertz area and a new operation were set up in a 50 hertz region a conversion would be needed for weld time. The formula is:
Weld Time @60 Hz X (50/60) = Weld Time @ 50 Hz
OR
Weld Time @50 Hz X (60/50) = Weld Time @60 Hz