fredsheldon wrote:Ok, I know nothing about electrical stuff. You guys have got me worried now. I just had a 120 20 amp and a 240 20 amp circuit installed in my garage. I have connected my SS to the 120 volt plug with a 15 foot 14 gauge extension cord. I will be connecting the SS to the 240 volt plug with another 15 foot 14 gauge extension cord that I have modified. Do I have anything to worry about and will I cause problems with my new PowerPro. Thanks in advance for any assurances you can provide
Go forth and prosper!:)
I was hospital visiting all day today and missed the 'fun' in this thread.
The switching power supply in the Power Pro will not react to different supply voltages the same as an inductive motor would. They 'typically' full wave rectify the incoming voltage and immediately charge a capacitor.
The subsequent circuits have the effect of discharging the capacitor.
The supply line current will occur only when the incoming supply voltage is greater than the then present capacitor voltage.
The lower the capacitor voltage, the greater the current, and the duration of that current.
There are other universal power supply schemes, but they will all draw current similarly.
So the current is dependent upon the motor demand, and is
almost the same regardless of supply voltage.
The small hp increase from 1 3/4 to 2 hp is because the capacitor has less time to discharge between 'cycles'.
This is all a gross simplification, but the results are essentially accurate.
So: There will NOT be a 2:1 decrease in current as in rewiring an induction motor from 115V to 230V.
The 'average' current will be only slightly greater at 230v than 115v.
At 230V, the line drop will be less 'detrimental' due to the increased supply voltage.(the capacitor will require slightly more time to charge)
The breaker size sets a maximum average current available to a circuit.
The wire size and length limit the voltage available at the load end of the circuit for a given load current.
As Dusty said, the 'load' does not care what size breaker is upstream from it. The load is however subject to the voltage limiting the intervening wire creates. That voltage variation
will affect the motor as mentioned by Ed, but he was referring to induction motors.
Now there is no advantage to 'matching' wire size to appliance cord since the bigger the wire the better for an extension cord. Due to the typical short length of OEM cords, they are usually also wire gauge 'short' as well.
We do not know the mechanical load/line current characteristics of a PP, but we do know that the PP has a ramped up start that eliminates the current surge that occurs with induction motors. It is that startup current surge that makes supply wire size a subject 'dear to our hearts'. It ain't there with a PP.
