Safco CS-I 150A - Advanced Welding Modes: PK, EK, AD

CS-I User and Maintenance, R.2.8 ENG
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7.5. Constant power, PK, introduction
In constant power mode, the voltage and the current at the tips are measured , and
eventually corrected , every ms, to keep their product constant depending on the fluctuation
of line voltage.
If the secondary resistance will decrease the current will be increased and vice versa, if the
secondary resistance will increase the current is decremented.
In this mode, the parameter "VE input" of voltage probe presence should be set to "YES"
and as with IK mode the calibration of machine is required.
The installation of the Rogowski coil, and of the voltage sensor at the tips are required.
The mode is active only in spot-weld cycles.
7.5.1 Constant power, PK, operative notes
1. After activating the voltage measurement, it is suggested that you test welding, working
initially in IK mode without slope. You must get good results this way the tracking power:
a. Correct any tails or excessive overshoot, by changing the gain parameter in the
menu Machine Calibration
b. Delete from the measure, the initial transient, using initial mask parameter, in order
to have stable measurements
2. Bring your system into the PK and change the welding program:
a. Fix the parameter "current limit" in this way the output current will not exceed the
level specified in any case even if is not reached the required power
b. Fix the desired power level
•
The welding at constant power, keeps constant the power over time, and therefore
the heat provided. The current trend therefore varies depending on the resistance, in
particular, you can expect a lower level of current at the beginning (when the
resistance is higher) and higher at the end, after the formation of the core
•
When the inverter works in PK, all distribution of the program are adjusted in power
and is available the same cycle program cases IK, V‰ and D‰.