Does changing the voltage capability on my TS allow me to work the saw harder or does it simply help prevent overheating and burnout and a few breaker runs?
I have already blown out a capacitor on the motor, ugh. (120volt setting)
By doubling the voltage, the current is halved. Therefore the I/R (voltage drop of the wire, which is a function of the current and resistance in wire) is cut in half. (more voltage to the saw). The saw starts better (the most current is on startup) runs better, cooler and should last longer. Just my $0.02
Frank
Brandt > Does changing the voltage capability on my TS allow me to work the saw
Every answer you get will be academic. The failed capacitor has nothing to do with what voltage you run. The best reason to run 220 is to be able run more tools on the feed without having to increase the feeder wire size.
Bob
Why would the saw run cooler if there is more voltage to the saw?
To first order, won't the saw consume the same amount of power when using
120V or 240V (assuming of course the motor is wired correctly for the appropriate voltage)? That said, in reality I think that saw will consume a little more power (maybe 5-10% more for a typical installation) in the 240V configuration than it would in the 120V configuration.BadgerDog
The actual motor wire carries the same current on either voltage. You are changing from parallel to series connection of the windings. The drop mentioned is in the feed wire. If it were very large wire, the saw wouldn't know the difference, but when more current is drawn and the saw starts to bog down, then the current goes up even more and things snowball. By keeping the voltage up by drawing less current on 220 and having less sag, you allow the motor to do its thing and produce rated power at rated current.
At lower voltage (sag) and higher current, heating rises in the motor because of IR drop in the windings. This is true at either voltage, but starts at higher loads because of less drop in the feed.
Yes.
How do you figure that? It is not logical.
Because the current is less, and it's current that generates heat, not voltage.
To a first order approximation, yes.
Why would you think that?
-- Regards, Doug Miller (alphageek-at-milmac-dot-com)
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Doug Miller asks:
Baffling. But I know people who swear that switching to 220 doubles a motor's power, too.
Charlie Self "The test and the use of man's education is that he finds pleasure in the exercise of his mind." Jacques Barzun
I have a 1 HP-110V Crapsman TS, whenever I saw hardwood lumbers the circuit breaker trips. I also encountered the tripping problems with my 1-1/2HP-110V compressor whenever the compressor loading. I rewired both machines to 220V and the problems gone forever.
I learn these tips from helpful posters here. By rewiring it to 220V you really have nothing to lose.
The power is the same I (current) x E (voltage)
110V x 20 amps = 2200 watts 220V x 10 amps = 2200 watts. Period! There are other loss that come into play (power factor) but lets leave that stuff alone! Also, You are "using" the same current in the motor (at 110 Vs 220) but since the voltage drop doing to the motor increases (less voltage at the motor), it draws more current to make up for the power loss (2200 watts)! So it works harder and the power lines get hotter (that where the loss is going.)Frank
Charlie Self wrote:
Oh, really?
Which generates more heat: 1) a 60-watt lightbulb (designed for 120V) running at 120v 2) a 60-watt lightbulb (designed for 240V) running at 240v
Note that #1 is drawing 1/2 amp, and #2 is drawing only 1/4 amp.
"Watts is watts", applies -- It doesn't matter how they're produced.
motor), it draws
This is almost correct, but your wording has me confused about what exactly you meant to say.
At 120V, when the current is approximately 2x, the voltage drop is greater in the feeder cable, so there's less voltage across the motor. That equates to less current per winding (they're in series here).
At 240V, since the current is roughly half, there's less voltage drop in the feeder, so more voltage is allowed across the motor, which will slightly increase the current per winding (which are now paralleled).
Of course, these variables all change with each incremental bit of developed power. So it's kinda moot.
And (to mention what others have alluded), it gets more detailed when you start considering the counter-EMF, mutual inductance, load rate of change, and power factor.
If you have the means to use 240V, just do it. It's advantageous.
Hope this helps. John Sellers
I agree that "Watts is watts" but wouldn't the temperature of the conductor(s) come into play since the resistance of a wire increases as the temperature rises?
-- Jack Novak Buffalo, NY - USA (Remove "SPAM" from email address to reply)
For a first order approximation, under 'steady-state' conditions, you _are_ basically correct. Needless to say, considering only 'steady-state' conditions is not really meaningful for analysing a table-saw. :)
The differences occur due to a variety of 'lesser' factors, including: 1) parasitic losses that are not directly related to applied voltage, 2) "stiffness" of the power _source_. 3) speed of response to varying load conditions -- when a motor is trying to play 'catch up' to an increased load, it draws more power than it does handling that same load at steady-state. The longer it takes to get back to steady-state, the more 'excess' power consumed. 4) 'non-resistive' (e.g. 'capacitive', and/or 'inductive') components of the load. (capacitance, inductance, and resistance react in _different_ ways, in parallel vs series circuits -- different from _each_other_, I mean. e.g. in series, resistance 'adds', but capacitance 'divides') 5) 'power factor' -- pretty much equivalent to #3
More commonly, it is the other way around, a device is slightly _more_ efficient at the higher voltage. On a _good_ day, it may approach 2%. :)
However, there are no 'guarantees'. It depends, _entirely_, on the design of the specific device.
John, series on 240, parallel on 120. When you have sag and current goes up, it's up in the feed as well as in the motor, so you actually do consume more power from the box, and a little more in the motor (the IR heating).
Including yours?
Consume more power? The first guy to respond to the question was spot on. Has everybody who attemps to reply actually run a bunch of tool on both 120 and 240? Same tools? Tried both ways? If you use a gawdawful heavy cord direct from the service panel, maybe you couldn't tell the diffence. In the real world, with similar gauge wiring, you'll find the saw will start quicker and bog less. Since it bogs less, it runs cooler. IMHO
rhg
BadgerDog wrote:
In the real world if you're using the same gage wiring for a 240 volt circuit and a 120 volt circuit that has to carry twice the current then it's time to sue the electrician.
"Could be... Could be", says he.
The light-bulb design already takes that temperature rise into consideration. The filament is designed to have the 'proper' resistance _at_operating_temp_.
Which is why incandescent bulbs _almost_ _always_ fail when they are turned on. The initial, or 'inrush' current is _many_, *MANY*, times higher than the 'operating current'. The 'cold' resistance of a 100 watt light-bulb is typically in the _low_ single digits.
As a point of engineering detail, the operating temperature of both bulbs will be fairly close to the same value. Incandescent bulbs of the same wattage are _amazingly_ close to each other in the 'color' of the light generated. which is _directly_ related to the temperature of the filament. A white light 'color temperature' difference of as little as 100 degrees C is easily detected by someone who is looking for it. Typical halogen white light color temperatures are around 4500 degrees. The 'white' on a color CRT is frequently in the mid 6000's. True daylight, if i recall correctly, is around 9500 degrees. Tungsten-filament incandescent, poor things, are down around 3000 degrees.
*IF* the filament in both bulbs is made of the same material, the 240v bulb has a filament that is longer and thinner than the 120V one.Frequently, however, the higher voltage bulbs are made with a somewhat _different_ (higher resistance) composition of material for the filament. Allowing the filament construction to be thicker than the 120V 'counterpart'. This improves the mechanical stability, and the ability to withstand shock and/or vibration.
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