problem with USA dewalt mitre saw

[dlath]

I am an American living in the UK. When I came over I brought my own power tools, (porter cable, Makita) and have been running them on a 3.3k site transformer for a few years with no problem. Now I brought my dw 718 mitre saw which runs sluggish and trips the breaker on the transformer even without a workload. I think the difference in cycles (UK 50Hz-USA 60Hz) is an issue here, even though the stuff I read and heard suggested otherwise. The saw is rated for 60 Hz and I should have payed attention to this. The other possibility is too low voltage on the 110 tranformer with a motor rated for 120 volts, but why would this cut out the transformer? Does anyone out there have any experience or insight into this to correct the problem so I don't have to lug a big expensive machine back on the plane?

 

[Newbie_Neil]

Hi

Welcome to the forum.

I believe that the symptoms you have are caused by the difference in cycles.

I'm sure someone will be along soon to confirm or otherwise.

Cheers
Neil

 

[OLD]

I think you should get the m/c electrically tested for insulation faults it should not trip the trans unless its got a very powerful/high current motor.

 

[ivan]

The 50/60 cycles thing applies only to induction motors (no brushes). 50 cycle induction motors have more iron and will run OK on 60 cycles. Other way round and 60 cyle motor will get rather hot on 50 cycles. Universal motors (all with brushes) will run on DC or AC of any frequency.

I have a DW 625, 621, and the 12" 2 way miter saw (706?) 115v all bought in the USA running from a 3kW site transformer for last 4 years.

 

[Sean the amateur]

I had the same problem when I moved from the US to Germany. A soon as I started my router the circuits blew both on the transformer and in the house.

The only way to fix this I believe is to plug in the transformer first, and switch it one before you start your tool.

Apparently when a transformer is turned on there is a very high voltge for a millisecond or two and this is what trips the circuit.

After the transformer has been on for a dewseconds, plug in your tool, and then turn your tool on last.

Hope this helps.

Sean

 

[Scrit]

Whenever I get that in clients houses it's a sure fire indicator of an earthing problem. I always power up the tranny then add the tools.

dlath, what is the motor rating (in Amps) of your DW? Whate is the rating (kVA) of your tranny? I ask this because DW apparently advise certain site tools be run on 'larger than calculated' size' transformers to cure sluggish start-up and possible started switch/motor/capacitor failure. According to my local dealer the DW742/743 flip-over saws are prone to this if run on a 3.3kVA tranny - I try to run mine on a 5kVA even though it's only running on a 13A circuit most of the time.

Scrit

 

[ivan]

Just finished watching an old" Taggart" on tv, went and looked at my mitre saw - it is a DW706 and the motor plate states 115v 15A. That's close to half a load for the 3kW transformer, a reasonable derating. Once the starting surge is passed, the unloaded saw will draw very little current - a feature of universal motors. I only run 1 machine at a time.

I read somewhere on this site a suggestion that some speed controls may not like a change in frequency, but this does not seem very likely as universal motor speed control does not depend on mains supply frequency for its mode of operation.