Variable frequency drives and soft starters
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In such a situation, there is a temporary device (a 22KW motor) equipped with a control box, which is started using a soft starter. Due to the insufficient length of the power cable, it was connected directly to the power inlet of another device on site (which is equipped with an inverter for starting). As a result, the soft starter burned out the moment power was supplied. Could it be that the soft starter was damaged due to the series connection of the inverter and the soft starter? I’m not very familiar with this circuit; please advise, experts
It’s really hard to explain – why isn’t the soft starter wired underneath the air switch at the upper end of the frequency converter?
First of all, I want to ask how on earth does someone who can think of such a response approach problems? Also, the burning issue is definitely not related to a series connection problem; it’s just that the wires aren’t connected properly. Series connection may not be useful, but it won’t burn out either if there’s no short circuit.
In theory, connecting a frequency converter and a soft starter in series should not cause the soft starter to burn out, unless the frequency converter is very powerful… Wiring faults could also be a possible cause. This solution is also quite... I mean, why not skip the inverter?
The inverter is in the power distribution room, so it’s definitely not possible to run cables from there. I think it’s quite likely that if the feeder cable of the inverter is long and the terminal voltage is high, this could damage the soft starter. Does the inverter have a reactor on its output side?
The frequency converter and the soft starter are the same size
……A frequency converter is connected in series with a soft starter – why does the soft starter get damaged? I think it’s due to mutual interference… The frequency converter has its own protection mechanisms, so there shouldn’t be any problems… I’m not sure……