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2.1 Phase-angle control with soft start and current limiting
Current limiting
Power units 05.01
In this mode of operation, the power is regulated by altering the phase angle.
This method is suitable for transformer and resistive loads. During the switch-
on period the phase-angle is gradually advanced by the controller to provide a
soft start. This prevents high surge currents at switch-on.
For loads with an initial (cold) resistance that is significantly lower than the re-
sistance after warming up, such as Kanthal-Super heater elements, it is advi-
sable to make use of current limiting (only with extra code TR or TO).
While current limiting is in operation, the phase angle during soft start remains
constant.
The maximum permissible effective (rms) current can be adjusted on the front
panel, by using the "current limit" trimmer.
v Section 5.3 "Setting the current limit"
2 Operating modes
13
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