ATTENTION ENGINEERS: Inductor to limit inrush when starting an electric motor?
The situation: I am using a contactor (like a big switch) to start a brushed permanent magnet DC motor. I am not using a motor controller. The motor is a Mars 0909 which draws 4.8 KW continuous and 15KW for 30 seconds
The problem: This current can cause arcing at the contactor which can erode the contactor's electrical contact points and perhaps stress the batteries or blow a fuse needlessly.
The goal: Reduce inrush while the motor starts up.
The question: My teacher suggested I use a large inductor in series with the contactor. Theoretically the inductor would resist the initial inrush of current and then its resistance would go way down. We looked around a bit and didn't find any motors in series with an inductor in series. Is there a reason why inductors an not typically in series with motors?
Is this something like a "Peterson coil" or an "arc suppression coil"?
Any idea what the formula would be to calculate the size of such a coil?
The problem: This current can cause arcing at the contactor which can erode the contactor's electrical contact points and perhaps stress the batteries or blow a fuse needlessly.
The goal: Reduce inrush while the motor starts up.
The question: My teacher suggested I use a large inductor in series with the contactor. Theoretically the inductor would resist the initial inrush of current and then its resistance would go way down. We looked around a bit and didn't find any motors in series with an inductor in series. Is there a reason why inductors an not typically in series with motors?
Is this something like a "Peterson coil" or an "arc suppression coil"?
Any idea what the formula would be to calculate the size of such a coil?
3
answers
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Answer it!
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Run the math, and size the inductor needed.
You should be using a motor starting contactor rated for the load, probably with magnetic arc breakers.
Unless you have active control big DC motor= big starting surge.
Steve
You should be using a motor starting contactor rated for the load, probably with magnetic arc breakers.
Unless you have active control big DC motor= big starting surge.
Steve
Also, big motors like that can ramp to speed VERY VERY fast. Make sure the motor is bolted to a strong suport, or it WILL bounce down the workshop
Steve
Steve
Your very correct Steve, we called them magnetic starters some automatic
some manual. They would limit motor inrush current in several steps and
were designed to Quench DC arcs.
I still have a Repulsion Start, Induction Run power planer motor. Alex
some manual. They would limit motor inrush current in several steps and
were designed to Quench DC arcs.
I still have a Repulsion Start, Induction Run power planer motor. Alex
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