Can a 3 phase motor be made 2 work on 2 phase voltage?

Question

A fellow that is SELLING says there is a unit that can be biult or bought that will allow a 3 phase (360 volts) eletric motor to be used with only 220 volts. Does anyone out there know if this is true? Since he is selling i am somewhat unsure.

Answer 1

Normal household power (220 V) is really single phase power, it is 'split' into two 110 Volt lines, but all are of the same phase.

It is possible to run a 3-phase motor on one phase with the methods mentioned above, plus this one:
If you can get the motor rotating by some other means (i.e. hand crank, another motor with a clutch) it will continue to run with only one phase connected (albiet at reduced power, torque, etc.).

Small motors (3 HP down to ~1/4 HP) that are *designed* to operate on a single phase use a capacitor to energize a small auxiliary winding to get the thing rotating. Once it is up to speed that winding is switched out, automatically.

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Answer 2

Take a look in Wikipedia for Static 3 phase converters or For Rotary 3 phase converters...Neither is more than 70% efficient though and in the case of the rotary convert or getting it to start sometimes is pretty hard as well. Cost ...??? well if you look in the right places and buy the right motor as well as capacitors you can build a 10 hp convert or for about 150 dollars ,,,that's about 5200 watts ...7460 x 70%..or there about ...The VFD can be purchased by the Horsepower single phase in three phase out ..the USED price for a 3 hp VFD is near 150 dollars the bottom line is if you have a motor requirement and you need to get a NEW motor buy one for the job....If you have a 3000 dollar shop saw that will not work on anything but three phase 150 dollars gets a little smaller....Good luck from the E

Answer 3

There are variable frequency drives (VFDs) that can accept single phase input and provide 3-phase output. Some of them have voltage doubler circuits that allow the maximum output voltage to be up to twice the input voltage. The price will likely be higher than the price to replace an existing 3-phase motor with a single phase motor. The utility may be unwilling to install 3-phase service for a small customer and the cost may be high if it is available.

For additional information, look at:
http://en.wikipedia.org/wiki/Variable-frequency_drive
http://en.wikipedia.org/wiki/Voltage_multiplier

Added info:
Although 120V 1ph in, 240V 3ph out VFDs are easily available in the USA, 240V 1ph input VFDs are apparently available in the USA only for 240V 3ph out. For a higher voltage motor, it would be necessary to use a transformer to increase the input voltage to the VFD. Higher voltage VFDs are not advertised as being suitable for 1ph input, but some can be used on 1ph with proper de-rating and perhaps some easy wiring and/or adjustments.

Small 3ph 380V and 460V (is 360 a typo?) motors can often be easily re-connected for 3ph 220-230V operation. If this is possible, it should be marked on the nameplate. That would eliminate the need for a transformer and make the VFD easier to find.

Getting the motor voltage to match the supply would also make it possible to run the motor on 1ph by connecting a capacitor. The torque and power would be reduced and it might be difficult to find the right capacitor, but it might work, but probably not if it is a 50Hz motor on a 60Hz supply.

For drives online:
http://web4.automationdirect.com/adc/Shopping/Catalog/AC_Drives_-z-_Motors

Answer 4

If one actually had two phase power, it could be done. But such power is almost non-existent; if you don't have three phase, you have single phase. And getting such a motor to run on single phase power would be difficult: you could do some things with inductors and capacitors, but the cost would exceed the price of the motor. Three phase power is available in many areas; if there is a pole line in yours, count the conductors sitting on insulators. You will need an extra pole transformer to bring in the three phase at low voltage if it is not already there.

Answer 5

If you split the DC voltage equally between 3 oscillators whose outputs phases were 120 degrees you could achieve a 3 phase output. I don't know what you could do with it,but hell it's a good question.

Answer 6

yes we can by butting one capacitors between any two phase