hi all, i have a car ramp that needs wiring in asap. However if i have single phase only at the moment can it be made to work tempory untill the 3 phase goes in without one of these expensive convertors?
3 phase motor on single phase?
- Thread starter mattysupra
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Nope, 3 phase is 3 phase.
Does the instructions for your item say that it can be connected as single phase. Some items can be relinked to opeate on a single phase supply but you'll probably need a BIG curent supply to make it work.
The ratings plate on the side may give you a clue..
Does the instructions for your item say that it can be connected as single phase. Some items can be relinked to opeate on a single phase supply but you'll probably need a BIG curent supply to make it work.
The ratings plate on the side may give you a clue..
A 3 phase motor relies on a rotating magnetic field for it to operate. Some say it is possible using a capacitor to create a phase shift hence get a rotating field, however how good it is is and how much torque it provides is another matter.
its second hand so not coming with instructions.
I guess there are 3 lives that pulse at different times on 3 phase? What happens if you connect all 3 lives to a single phase? Power is not a problem ( amps ) and to be far i do have 3 phase its just locked away in the meter cubard that i cant get into for a couple of weeks.
I guess there are 3 lives that pulse at different times on 3 phase? What happens if you connect all 3 lives to a single phase? Power is not a problem ( amps ) and to be far i do have 3 phase its just locked away in the meter cubard that i cant get into for a couple of weeks.
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There are 3 sine waves which are all 120º out of phase with each other.
It won't work.
O.k thanks. Guess i will have to wait untill the elecy cubard is opened up for me. might just cut the padlock off and replace it when the key holder gets back of there hols. Might upset the landlord but really need this ramp working monday morning!
LOL, i would not do it myself! I have a spark who will be doing the work for me! Thanks for your advice tho mate.
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Three phase motors can often be configured as star or delta on the larger motors delta is 400 volt and star is a lot higher and because of the voltage they can't be used on single phase. However the smaller motors can often be wired as 400 volt star and 230 volt delta and these can be run with an inverter from a 230 volt supply. The inverter will also reduce the start current and allow the motor to be run without making all the lights both in yours and neighbours house dim every time you switch on the motor.
You will not normally have a three phase supply to a house and to get a three phase supply will likely cost more than an inverter.
There are other ways to turn single phase into three phase but would need to start with no load and in real terms not really worth while now inverters are so cheap.
Long remembered the battle Nikola Tesla and Edison I am glad Tesla won.
Eric
You will not normally have a three phase supply to a house and to get a three phase supply will likely cost more than an inverter.
There are other ways to turn single phase into three phase but would need to start with no load and in real terms not really worth while now inverters are so cheap.
Long remembered the battle Nikola Tesla and Edison I am glad Tesla won.
Eric
B
breezer
You need to have 3 changing magnetic fields i.e. 3 phases to get the rotational effect required by a 3 phase motor, not sure where the higher voltage for star comes into play? In star if you wanted the same power output then a higher voltage would be required, the motor should still spin up with a reduced power output and starting current in star (providing of course the torque is adequate to start the load), but why go to the expense of that when you can run it in delta, or even star/delta start.
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If you look on the plate of a motor rated 400 volt delta it will also be rated 695 volt star running a motor designed to run at 695 volts on 400 volts will allow it to start up with reduced current then change the winding so it is configured to run on 400 volts once it is already turning will then give it full torque without drawing excessive start current this is normally referred to as star/delta starting. On larger motors this is still not enough reduction and either auto transformers or resistors are used to reduce starting current instead of two stage it then can use multi-stages.
This is where the voltage comes into play.
And of course poly phases are required to rotate squirrel cage motors however using capacitors these can be produced without using a three phase supply years ago before inverters this was quite common and the factory would start one motor which would produce a false three phase supply and each motor used would re-enforce this. I have not seen this method used for many years.
Eric
This is where the voltage comes into play.
And of course poly phases are required to rotate squirrel cage motors however using capacitors these can be produced without using a three phase supply years ago before inverters this was quite common and the factory would start one motor which would produce a false three phase supply and each motor used would re-enforce this. I have not seen this method used for many years.
Eric
I have seen a few different technologies used to reduce start up current with 3 phase motors - spinning the motor up to full speed DOL delta then applying the load via a magnetic clutch is one method - also gives a bit of speed control.
These are being replaced by VSDs though as they are more efficient.
Slip ring motors can also be used to give high torque at low speeds taking out the resistances as the motor ramps up.
These are being replaced by VSDs though as they are more efficient.
Slip ring motors can also be used to give high torque at low speeds taking out the resistances as the motor ramps up.
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