| Author | Message | ||
| les marston (Les_marston)
Registered Member Username: Les_marston Post Number: 209 Registered: 1-2010 Posted From: 68.151.225.213  Rating: N/A |
A friend and I had a discussion that started out, as most do, over a small item. In this case snowblowers, particularly gas powered with 110 volt AC starters. The question was this. My friend insisted that his snowblower starter was polarity sensitive and if plugged in backwards the motor would turn backwards. This is an AC motor. I know because I had the same unit. I told him that as far as I know AC motors would still run the same direction if load and neutral got switched. He claims not.... I looked on the internet but only found that what I believe to be true. Is there some exceptions to this? Just one of those niggily things that I have to add to my wealth of useless knowledge Thanks Les | ||
| thomas flocks (Taflocks)
Registered Member Username: Taflocks Post Number: 405 Registered: 9-2009 Posted From: 67.253.124.108 Rating: N/A |
it only turns one way if it is ac | ||
| macgyver (91flyer)
Registered Member Username: 91flyer Post Number: 608 Registered: 11-2004 Posted From: 173.217.47.28  Rating: N/A |
The "Polarity Plug" that's used today is there to ensure that ground and hot don't get crossed, since ground and neutral are, in most cases, tied together. Some devices internally ground to neutral, thus avoiding the use of the ground prong altogether... By plugging it in backwards ("reverse" polarity), you render the internal grounding useless and open the device up for all sorts of fun stuff... including the possiblity of killing you easier (as if electricity needed any help whatsoever in that department!) Now, I may have my terminology slightly goofed here, and if that's the case, someone correct me... But I believe this to be the reason for the "polarized" plug's introduction... -Mac | ||
| George M. Todd (George_todd)
Registered Member Username: George_todd Post Number: 1162 Registered: 8-2006 Posted From: 99.56.244.104 Rating: N/A |
Pretty close, but actually the two prong devices are double insulated, instead of having a grounded frame via the third wire. Older electric dryers and stoves only had a 3 wire plug, with grounding either thru the neutral or a wire from the frame to a water pipe, etc. A hazard waiting to happen, and a real problem in a bus with completely seperate ground and neutral always. To answer the question, and please don't hit me. It is AC right? As in alternating current, as in no polarity? Difference of potential to ground doesn't apply with two wires, so it will always turn the same way, unless the direction of current flow is reversed in the stator with relation to the rotor. G (Message edited by George_todd on December 12, 2010) | ||
| les marston (Les_marston)
Registered Member Username: Les_marston Post Number: 210 Registered: 1-2010 Posted From: 68.151.225.213 Rating: N/A |
I don't see how it would be possible to change the direction of current flow without rewinding the motor. In that case it would spin the other way however I don't think that some little electrical genie was in the motor magically rewinding it each time the load and neutral got reversed on the two prong plug. I think that the general consensus is I am right and my friend is mistaken. Don't get me wrong on this it is not a na na na na na situation I wasn't out to just prove him wrong. I just was not sure that there was not some way for it to be possible for that little AC starter motor to spin the opposite way Thanks guys Les |