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Join Date: Sep 2011
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Connect Three Phase Motor to Single Phase Supply

09/23/2011 1:19 AM

what will happen if i connect three phase motor to single phase supply?

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#1

Re: connect three phase motor to single phase supply

09/23/2011 1:23 AM

Nothing, as long as you don't energize the circuit.

Why would you even consider this?

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Guru

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#2

Re: connect three phase motor to single phase supply

09/23/2011 2:07 AM

Won't work. There a few discussions on here about hooking up three phase motors to single phase.

first.

second.

Three.

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#3

Re: connect three phase motor to single phase supply

09/23/2011 2:18 AM

If you are looking for a motion it won't rotate.Single phase don't make Rotating Magnetic Field(RMF).

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#4

Re: connect three phase motor to single phase supply

09/23/2011 2:36 AM

It will probably trip the overload protection (if any). If none, it may burn up the motor. This condition is known as "single phasing."

Perhaps you mean a different question: There are VFDs that can accept a single-phase supply and produce a 3-phase output.

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#5

Re: connect three phase motor to single phase supply

09/23/2011 4:21 AM

All other things being equal, a circuit protective device will operate, disconnecting it.

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#6

Re: connect three phase motor to single phase supply

09/23/2011 4:31 AM

a three phase squirrel cage induction motor will have either three terminals or six terminals . . . they will be numbered (marked) something like this . . . U, V,W or L1, L2, L3 in case of a three terminal motor . . . the six terminal motor will have markings 1U,1V,1W & 2U,2V,2W or U,V,W & R,S,T . . . .

the three terminal motor is pre-connected in DELTA unless stated otherwise on the name plate . . .

the six terminal motor has each winding brought out giving the user the option to connect it in STAR or DELTA for starting or running . . .

now tell us which of the above descriptions applies to your motor?

and then if you propose to connect a single phase supply to the motor then which 2 terminals will you connect the supply at?

if you help us with proper information we promise to help you with an answer . . . .

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#7

Re: Connect Three Phase Motor to Single Phase Supply

09/24/2011 10:30 AM

Not possible and have a good motor working after you energize the system.

If you only have single phase at your location, it would be either 2 options to follow.

1) get a single phase motor to do your work.

2) this will cost more, but can be done. You will need to purchase a single to 3 phase converter transformer before you can make this devise run. Sounds like you have an industrial piece of machinery at a residential location. Your power supply will need to be able to handle the load factor as well from this kind of equipment. Be prepared to pay for the extra juice to run such an item. Good luck

Maximo

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#8

Re: Connect Three Phase Motor to Single Phase Supply

09/24/2011 1:12 PM

"what will happen if i connect three phase motor to single phase supply?" We call it a Very inefficient "heater".

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#9
In reply to #8

Re: Connect Three Phase Motor to Single Phase Supply

09/24/2011 1:35 PM

please define "efficiency of a heater".

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#10
In reply to #9

Re: Connect Three Phase Motor to Single Phase Supply

09/25/2011 12:06 AM

I believe the "sarcasm" was it "won't run" Just heat up like an electric heater. But not design as such. just my 2cents.

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#11
In reply to #10

Re: Connect Three Phase Motor to Single Phase Supply

09/25/2011 12:27 AM

o yes i saw that it will heat up and all the sarcasm . . . but i still want to know how to define the efficiency of a heater . . . .

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#16
In reply to #11

Re: Connect Three Phase Motor to Single Phase Supply

09/30/2011 5:26 AM

I see where you are going. In a lot of electrical plant (or elecrical energy to other energy conversion components), since the conversion efficiency is not perfect we get less than 100% efficiency and the losses generally end up as heat. But if our objective is to get heat, what do the losses end up as? Heat?

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#12
In reply to #9

Re: Connect Three Phase Motor to Single Phase Supply

09/25/2011 8:25 AM

When heating device is energized, heats up, and trips the protective circuit, I would call that "inefficient".

But it was supposed to be a joke...

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#13
In reply to #12

Re: Connect Three Phase Motor to Single Phase Supply

09/25/2011 8:51 AM

of course it was a joke . . . tripped the circuit too . . .

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#14

Re: Connect Three Phase Motor to Single Phase Supply

09/25/2011 12:00 PM

If it is a standstill motor that you are connecting the single phase supply to, then the three phase motor wouldn't start and if your system does not have an effectiv eprotective device, the motor winding insulation might fail.

Else, if it is a running motor and you remove 'one line' thus causing single phasing, in the absence of an effective protective device in the circuit, either winding insulation damage or rotor damage or both could happen.

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#15

Re: Connect Three Phase Motor to Single Phase Supply

09/29/2011 11:09 PM

motor will be burnt out...it would just humm...but will not sing(rotate)

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#17

Re: Connect Three Phase Motor to Single Phase Supply

10/05/2011 9:47 PM

Somebody ever try this..it wont work, and the single line that power up, yes it heats.

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electricalexpert65 (1); hithuanand (1); JRaef (2); loadshare (1); LordMaximo (1); lyn (1); metalSmiths (2); mmofu (1); PWSlack (1); rockraiden (1); soebfatehi (4); Tornado (1)

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