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Inverter inrush current

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JVR:
My brother works on earth moving equipment.  His bakkie (ute) has a 800W 230V inverter that needs to drive a 550W drill and a 650W grinder.

The problem is that the inverter can't start the tools at full power, this is ok with the drill, as he can speed it up slowly using its own speed control, but the grinder just trips the inverter.

What I've thought of was to build a "dimmer" for the inverter, so he can start the grinder at a low speed, but this is not an ideal method.  Can a softstarter be fitted? Or is there another way of helping the inverter deal with big inrush currents?

Thanks!
JVR

Zero999:
The grinder probably uses an induction motor.

You can buy proper soft start for it or running it from a variable frequency drive will also work

JVR:
VSD would be nice, but its completely out of budget :(

Being a digital type, what would happen if he fitted a 400V cap over the lines? The way pool motors have them fitted?
Like so?

Psi:
I wonder what would happen if you put a ~39uF 250VAC capacitor in series with the grinder.
39uF @ 50hz would limit the current to 2.8A (644W)
I have no idea what sort of effect it would have on the grinder motor though.

If the grinder started spinning you could then bypass the cap with a switch or relay+timer when it was up to speed.

hehe, note the word "bypass", not "short out"
39uf @ 230v would be the end of the relay i think :P.

mikeselectricstuff:

--- Quote from: Hero999 on October 15, 2011, 07:07:57 pm ---The grinder probably uses an induction motor.

You can buy proper soft start for it or running it from a variable frequency drive will also work

--- End quote ---
Only if it's a bench grinder - an angle grinder will be a universal motor like the drill - you could soft-start the latter.

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