gefran GFW-Xtra 40 Installation And Operation Manual page 38

ADDITIONAL FUNCTIONS
Softstart
This type of start can be enabled either in phase control or pulse train mode and in zero-crossing mode (ZC, BF,
HSC).
In phase control, the increment of conduction angle q stops at the corresponding value of the power to be transferred
to the load.
Control of maximum peak current (useful in case of short circuit on the load or of loads with high temperature
coefficients to automatically adjust start time to the load) can be enabled during softstart. When the load shut-off time
(settable) is exceeded, the ramp is reactivated at the next power-on.
Figure 51
RMS current limit
The option for controlling the load current limit is available in all work modes.
If the current value exceeds the limit (settable in the nominal full-scale range) in mode PA the conduction
angle is limited, while in zero-crossing mode (ZC, BF, HSC) the cycle time conduction percentage is limited.
This limitation ensures that the RMS value (i.e., not the instantaneous value) of the load current does NOT
exceed the set RMS current limit.
Figure 52
Example of conduction angle limitation in PA mode to respect an RMS current limit below the nominal current of the
load.
38
Example of firing ramp with phase Soft-Start
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