How long is an inductive motor surge?

[greg273]

  I have a Trace DR1512 inverter, which gives a 1msec surge rating of 32 amps, and a 100ms surge rating of 27 amps.  Will i be able to run my 15amp circular saw without damaging it or tripping the breaker?  I know its cutting it close....

[Kevin L]

I don't think you will be even close.   I would expect a circular saw to well exceed 90 - 150 amps for several msec.  I havent measured it but the current draw is huge during the initial second of use.  Maybe a large audio 1 farad cap at the 12 Volt input of the inverter may help, and if you had a way to get the thing spinning before appling the power, but then again that sounds dangerous.

Maybe someone else who's tried it will have some input.

Kevin L

[kell]

Maybe you just need to find some way to soft start it.  A dimmer switch with a high power rating?  Of course, you would have to turn the knob every time you pull the trigger on the saw.

[John II]

Hello greg273: Could you give us more information here ?

Is this a table saw, a radial arm saw, or a hand held circular saw ?

If it's a hand held circular saw, it probably has brushes. If it has brushes, you'll start it with ease.

If it's a table saw you could perhaps put a DC brush type 120vdc motor on it and install a bridge rectifier (converts ac to dc) and still run it.

If it's a big induction motor (no brushes) then those things can demand 6 times as much surge as running current. If your inverter has a "soft starting" feature, it'll start more items then you might suspect. But if it's a pure induction motor of that size (no brushes) then it'll probably take a larger inverter to spin it up to speed.

John II

[bob g]

i personally don't think you will have any problems at all powering your saw.

check out:

www.ibiblio.org/.../environment/alternative-energy/energy-resources/homepower-magazine/archives/2/02
pg29.txt - 7k

hopefully the link will work.

bob g

[greg273]

  Its a 15amp Milwaukee 7.25" hand held circular saw.  I also have an older Delta 10inch table saw ( not sure of its Amperage ).

[John II]

Bottom line..

if it has brushes, you'll easily start it.. I never saw a hand held circular saw that didn't have brushes... So I'm sure the inverter will run it just fine... you can pretty much count on it running for sure.

Some small table saws use a brush motor.... If it does it'll start easy. If it happens to be a standard induction capacitor start motor... you still might accidently start it.. (depends on motor size) If it's an induction motor without capacitor start, then you probably won't be able to start it. But the nice thing about table saws is that you can find a easy to start motor and put it on it.

John II

[greg273]

  Thanks to everyone for the quick posts!  

[Volvo farmer]

I'd bet it would. The trace DR stuff is pretty famous for starting inductive loads. I've got a crappy $100 Xantrex Xpower 1500 and it almost starts my 13A circular saw. If I hold the trigger long enough or shake the saw, it actually has started it once or twice. This abuse did not damage the inverter as far as I can tell.