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Discussion Starter #1
I have a Leeson motor 230 v 3450 rpm 4hp on a delta unisaw but can’t find what phase it is, any suggestions?
 

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Bah humbug
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Have wire coming off it, a plug?
 

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where's my table saw?
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This is probably it:
 
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your options are
two phase, ie std household 240v circuit.
three phase - rarely rarely found in residential - where did the saw come from?

two phase will have three (or four....) wires - the two hot legs L1 & L2 typically black and red, a neutral white, a green ground

three phase is a bit more varied depending on age.... but the L1/L2/L3 legs are typically black-red-blue with a white neutral and newer with a green ground.
 

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Discussion Starter #5
your options are
two phase, ie std household 240v circuit.
three phase - rarely rarely found in residential - where did the saw come from?

two phase will have three (or four....) wires - the two hot legs L1 & L2 typically black and red, a neutral white, a green ground

three phase is a bit more varied depending on age.... but the L1/L2/L3 legs are typically black-red-blue with a white neutral and newer with a green ground.
your options are
two phase, ie std household 240v circuit.
three phase - rarely rarely found in residential - where did the saw come from?

two phase will have three (or four....) wires - the two hot legs L1 & L2 typically black and red, a neutral white, a green ground

three phase is a bit more varied depending on age.... but the L1/L2/L3 legs are typically black-red-blue with a white neutral and newer with a green ground.
your options are
two phase, ie std household 240v circuit.
three phase - rarely rarely found in residential - where did the saw come from?

two phase will have three (or four....) wires - the two hot legs L1 & L2 typically black and red, a neutral white, a green ground

three phase is a bit more varied depending on age.... but the L1/L2/L3 legs are typically black-red-blue with a white neutral and newer with a green ground.
This is probably it:
This is probably it:
This is probably it:
Thanks for your information. I cleaned up the spec plate on the motor and found PH 1. Also three wires on the plug, black, white and green.
 

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your options are
two phase, ie std household 240v circuit. Technically, this is single phase with 2 legs.
three phase - rarely rarely found in residential - where did the saw come from?

two phase will have three (or four....) wires - the two hot legs L1 & L2 typically black and red, a neutral white, a green ground

three phase is a bit more varied depending on age.... but the L1/L2/L3 legs are typically black-red-blue with a white neutral and newer with a green ground.
... see in red.
 

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CharleyL
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Two phase is correct technically, but the second phase is created within the motor and serves only to start the motor turning.

You need the second phase to make the motor start and run the correct direction. The motor design uses a second winding (second phase) positioned about 90 deg magnetically away from the main motor winding. It has an AC capacitor to shift the sine wave, and a centrifugal switch to turn off this winding once the motor is coming up to speed. From then on, while the motor is running, the motor is running on single phase, so it is considered to be a single phase motor. Phasing refers to the timing relationship of the AC power sine wave that feeds the different windings of the motor. The second phase, for the temporary use starting winding of a single phase induction motor is created by a time shift in the incoming sine wave of the AC power that is feeding the motor. It provides the direction (depending on polarity relation to the primary winding), to give the motor a kick in the desired direction, as well as help the motor get up to speed. It is of a high current "temporary use" design to create this "kick" and it would quickly burn up if not disconnected by the centrifugal switch once the motor is coming up to speed.

Three phase motors use three power lines for input, with each AC sine wave provided on them delayed by 120 degrees from the previous input sine wave, making three points (actually 6 counting the plus and minus polarities) in the magnetic field of the motor, so each peak voltage of the sine wave is 120 degrees apart from the others, and 3 X 120 = 360 degrees or a full rotation of the motor. No start windings, switches, or capacitors are needed, since 3 phase power is provided that way from the power company. To reverse the motor, you only need to swap two of the phases, and the motor will start and run in the opposite direction.

Our commonly available "House Power" in the USA is center tapped single phase and not two phase. The center tap is Neutral and is grounded for safety reasons. Between each of the other power leads and the center tap Neutral provide 1/2 of the totally available voltage of 240 volts (if Delta connected by the power company), so each hot leg is 120 volts nominal and across the two is 240 volts nominal. It is NOT 2 phase and will not start a single phase motor with a starting winding directly, without the addition of the capacitor and starting switch needed to create and delay the sine wave to create the second phase for starting the motor.

I'm an EE guys.

Charley
 

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CharleyL
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so this bit calling things Phase 1 and Phase 2 is incorrect. View attachment 425014
Only when talking about the USA incoming 120/240 volt household power system.

Within a single phase induction motor designed to work on household 120 or 240 volts AC, a second phase is created by tapping off and then delaying the sine wave by using a capacitor to create the second delayed phase to feed the motor starting winding. This delay circuit is not designed for continuous use, and it draws a lot of current. It is only used to kick the motor into motion and assist with bringing the motor up to speed. At about 1/3 of the motor's rated operating speed, this second phase circuit gets disconnected by the centrifugal switch within the motor. If it fails to disconnect, the capacitor and starting winding will not last long before they burn up.

If you open a single phase motor and disconnect the capacitor, or this starting circuit at any point, and then try to run the motor, the single main motor winding will just cause the motor to hum when the power is applied. It won't start on it's own. Now, while it's humming, if you spin the motor shaft (but not with bare fingers) the motor will run, but in either direction depending on which way that you spin it. Starting and direction are dependent on the second winding, the capacitor, and the centrifugal start switch circuit and how they are connected together. By changing this connection in the right way, you change the direction that the motor will start and run.

So yes, there are two phases, but only within the motor. It is not part of the home electrical power system. Think in terms of batteries about this. Two dry cell batteries connected end to end will produce about 3 volts, but across each battery, from their center connection to either end, you only get 1.5 volts. Now, for safety we connect this center point to ground. You still get 3 volts across the two cells and 1.5 volts across either cell from the middle connection to the end of either cell. 3 volts when connecting to the ends of the two cells.

Grounding the center point of a household power system makes certain that if lightning strikes or if the power lines outside the house should ever touch each other, that the voltage from either incoming power lead to Neutral and ground in the house will not significantly exceed their rated voltage before a fuse or breaker will trip to shut it off. This keeps the system much safer from these occurrences than if the center point (Neutral) wasn't grounded.

BTW, a bad Neutral connection to a house will cause the 120 volt appliances that some connect to one of the 120 volt line and some to the other 120 volt line to be in series with each other. Depending on the loads, Some appliances will get too much voltage, while those on the other input line will have too little input voltage. Now, think about flickering lights in your house. They all run on 120 volts, but when they are running off the two power leads coming into the house, some will dim when an appliance starts, while others get very bright and even burn out. Dimming lights are an indication of a drop in voltage on the power line that it is connected to.

Lights going suddenly very bright are an indication of a bad service Neutral or service ground in a home or business, but old main fuses can have high resistance and cause similar problems. I helped a restaurant owner who was having this problem one time when I was eating there. I commented to him about the lights going bright and dim, and he said that he had 4 different electricians look at it and none could figure out what was happening. While eating, I went back to his electric panel and wiggled a few Neutral and Ground wires and quickly found one big Neutral wire with a bad connector. Wiggling it made it spark. He brought me a screwdriver and I tightened the connection, and no more flickering or over bright lights. I got a free meal and an invitation to come back another night for a full free meal with wine and desert. (This was a pretty fancy restaurant). Such an easy fix, but the local electricians had no idea what the problem was.

Charley
 

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no motor can create 240 volts out of single phase 120v.
if you wish to insist that two legs of 120v out of phase by 180' going to the motor is simply single phase, enjoy.

the rest of the babble is not related to any question raised by any poster.
 
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