Powering 220v Tools With A Generator

[Kevin Post]

I recently moved to a temporary home with no 220v power in the garage. Our old house sold and our new house is still not ready. We're renting a duplex for a couple of months.

The closest 220v power inside the duplex is either the dryer or the range. Either would require a 75 ft cord to reach. I didn't feel it would be safe to run a drop from the dryer hookup so I bought a generator. It's a nice rig rated at 6KW (8.5KW starting).

Here's the problem... None of the machines equipped with a magnetic switch (tablesaw, shaper, planer) will operate from the generator. The motors try to start but switch will not engage to keep them going. Machines with a conventional (non-magnetic) switch work fine (dust collector, drum sander, molder).

Any solutions?

-Kevin

[Don Baer]

It sounds like the voltage is sagging when you try to start the motors and it is going low enough to where the magnetic starter coil can't pull in. I don't know an easy solution. Are you there other loads on the gen set when you try to start the saw/shaper/planer ? Like maybe the DC. If so start the ones on with the mag pickup first then start the DC. See if that helps. Oh, yea one more thing, what HP are the saw/shaper planer ?at least run my tools.

Oh and I can sympathise with you on your situation. I am living in temp house until mine gets built. I'm in the process of wiring the Garage to where I can run my shop. 1 110V duplex recepticle in a garage is a PIA expecialy when I have a freeser, Refrigerator, table saw, planer, CMS, lathe, band saw, jointer and various hand tools to power..

And LOML has numerous project for me to complete before the house is finished.

[Robert Mickley]

I had this problem!!! I was trying to run stuff off of a Lincoln Ranger 8 welder. if it was on auto it wouldn't strat stuff with a magnetic switch, also it wouldn't start the air compressor, if I ran it on manual high idle everything was ok

[Kevin Post]

The generator doesn't have an auto-idle so it's ready to go all the time. Of course, the engine bogs down when the additional load is encountered.

I've tested this a number of different ways with no other load on the generator. The common denominator is the magnetic switch. My air compressor starts right up and that's what most people say gives them trouble when operating on generator power.

I may end up bypassing the magentic switches on these machines temporarily until I get them to their new home. I plan to contact JET and Delta today to find out if this will create a problem and to find out if they have any other recommendations.

-Kevin

[Steve Clardy]

Wouldn't it be less headaches to go ahead and get that 75' cord, wire in an enclosed box with breaker's on the end of that cord?
Put you in a 20 single, and a double 20-30, or whatever you need.

[John Lucas]

Just a thought. Get two motors going and at the exact moment you push the ON of the TS, turn off the two motors. You might be able to fool the draw of the MG.

[Kevin Post]

Wouldn't it be less headaches to go ahead and get that 75' cord, wire in an enclosed box with breaker's on the end of that cord?
Put you in a 20 single, and a double 20-30, or whatever you need.

Well, you know, Steve, hind-sight is a wonderfull thing. Where were you when I bought the generator? I bought it, I couldn't return it and by God I was determined to find a way to make that thing work.

I spoke to a tech at JET who told me he calculated the current required to start the 3HP motor on my tablesaw at approx. 26 kilowatts. I don't know how he calculated it but my gut tells me he's probably full of beans. Nevertheless, there is a protection circuit in the magnetic switches for these tools that doesn't like the electrons from my new generator. (Who knew tools could be snooty like those people who will only drink imported, bottled water?)

I've been in situations like this enough times to know I was fighting a losing battle. I overcame my stubborn nature and made a cable to run power from the dryer circuit. So, I've wasted $600+ on a generator I don't need and probably won't use again. SWMBO will never let me forget that!

The generator only had 1-30 amp 220v outlet. I had already made a drop from the generator with 25 ft 10/4 cord and a 2-space box mounted on a board. I put in a 30 amp breaker and added two 220v outlets so I could run one tool along with the dust collector at the same time.

The dryer is on a 50 amp circuit. I bought an additional 50 foot length of 10/4 cable and put connectors on either end. The female, 30-amp generator connector cost about $24! I exchanged the 50-amp breaker protecting the dryer circuit for a 30 amp to make sure I didn't overload my 75 foot cable. (This may not have been necessary but...)

Just a thought. Get two motors going and at the exact moment you push the ON of the TS, turn off the two motors. You might be able to fool the draw of the MG.

Sadly, I tried this too by starting the dust collector first, then shutting it off at the moment I started the tablesaw. It didn't work. Could you imagine how productive I would be switching things on and off trying to get the tablesaw to go? Maybe, if I trained some monkeys... Nah, monkeys would cost a lot more than the generator and all the extra wire combined. (Not to mention... they throw poop.) I think taking the power from the dryer circuit is the best option. It just took a little time to overcome my stubborn nature and accept the fact I had wasted a bunch of money on a generator I can't use.

Thanks all for the suggestions. I still can't believe it takes 26 KW to start a 3 HP motor...

-Kevin

[Don Baer]

Thanks all for the suggestions. I still can't believe it takes 26 KW to start a 3 HP motor...

-Kevin

Kevin,
I just looked up the starting current for a 1 phase motor in my Emerson Electric US motors pocket guide and it says that a motor will draw anywhere between 3-9 times the FLA on start deppending on the design. that calulates to anywhere between 10-30 KW starting load

Not knowing the what motor is involved it could very easily be 26KW

[Steve Clardy]

I get pretty tight fisted when it comes to temporary stuff I guess.
I've done some pretty strange, and maybe unsafe stuff sometimes.

You could always build you a small cover for that generator and sit it outside and get a connection to hook up to your shop/house in case your elec. ever goes out.

Check with power co. if you do though.
I'd love to have a generator here at home for that reason. I live out in the sticks. But being here for eleven years and being without power for maybe a total of three hours, probably not worth it to me.

[Kevin Post]

You could always build you a small cover for that generator and sit it outside and get a connection to hook up to your shop/house in case your elec. ever goes out.

That's an option I had considered. Not so much for the shop but rather to keep the refrigerator, freezer, furnace and some lights going in the event of a power failure. (But really, what good is it if I can't run my tablesaw? ) The power company doesn't need to know but I'll need to have a transfer switch installed by an electrician.

[Ralph Barhorst]

Kevin,

The rated power of many generators is optimistic at best. A very good generator can put out 500 Watts per horsepower. Therefore, your generator should have at least a 12 HP engine.

The comments about the amount of starting current are correct. The starting current can be many times the run current.