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I have a winch that I would like to supply with a DC switching power supply. The winch has a current of approximately 40A at 24V under the specified load, but the inrush current will be much higher, I think over 100A. What I would like to use as the supply is a 24V, 100A switching power supply, which has a current limiting function and will shut down after 5s of overload. Since the inrush current will settle down to the nominal current in no time, I think the power supply could handle this. Am I right?

Power Supply: http://cdn-reichelt.de/documents/datenblatt/D400/RSP_2400_XX.pdf

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  • \$\begingroup\$ Measure DCR of motor and compute the inrush. I expect it will be more than 2.5x rated current. possibly 8x \$\endgroup\$ – Tony Stewart Sunnyskyguy EE75 Nov 19 '17 at 14:32
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According to the datenblatt, the PSU is programmable to either deliver constant current, or to deliver constant current and then shutdown after 5 seconds. So it looks like you need not have a problem with shutdown if the winch doesn't accelerate fast enough.

The inrush current from an unlimited supply may well be very high, but as your PSU has a current limited output, that will define your starting current. This means the winch will have a lower starting torque than would be expected for starting from a battery.

As the specified load takes 40A, then at a limited 100A, you will have up to 6.25 times the rated load torque for starting, or less if either of your armature or stator saturates at 100A.

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  • \$\begingroup\$ Ok, then the PSU should be able to control such type of loads? Will it be save to use the PSU for several seconds at this maximum current limit rating? \$\endgroup\$ – HansPeterLoft Nov 19 '17 at 14:40
  • \$\begingroup\$ 6.25 times or 2.5 times? \$\endgroup\$ – Brian Drummond Nov 19 '17 at 15:49
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    \$\begingroup\$ @BrianDrummond If all the iron stays out of saturation, 6.25 times, 2.5x as much armature current in 2.5x as much field. Less if one or the other saturates. \$\endgroup\$ – Neil_UK Nov 19 '17 at 20:53
  • \$\begingroup\$ @HansPeterLoft read the data sheet in detail, and then do some tests. The short sheet you linked to suggested it would limit at 100A indefinitely. \$\endgroup\$ – Neil_UK Nov 19 '17 at 20:55

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