What is the reason why the ABB soft starter cannot be switched to line frequency?
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The ABB soft starter can automatically switch to line frequency when unloaded, but it cannot do so automatically when under load, provided there are no faults in the control circuit.
During variable-frequency operation, its voltage phase is not necessarily related to the phase at the power frequency. When switching from variable frequency to fixed frequency, if the phases are the same or similar, then the conversion proceeds without issues. If the difference is large, conversion is not possible.
By power frequency, the poster is referring to the switch to the bypass contactor mode, right? If that’s the case, it’s likely that the parameters for soft start haven’t been set properly
First, check the current; if it is too high, conversion may not be possible. Check again to see if your parameters allow for forced switching.
That shouldn’t be the case. I’m using several 75KW fans here, and I haven’t encountered the problem you’re talking about
Fan-type loads have high inertia and generally take a long time to start. Could it be that the soft-start time was set too short, causing the system to switch to normal frequency before the required current level was reached?
This post was last edited by zyz8438 on 2010-7-26 at 16:23. The original poster did not clarify whether \"it cannot automatically switch to the power frequency under load\" means that the soft starter never performs the switch over at all, or that it switches over but then stops working immediately Different phenomena can have their causes analyzed and determined!