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The formula for RPM is ; RPM = Hz x (120 (constant)) divided by the # of poles. Number of poles a motor has; # of poles = Hz x (120 (constant)) / RPM.

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Q: What is the maximum RPM does a 3 phase motor run at?
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What is the minimum voltage a 115vac 400hz 3 phase motor will run?

Yes the minimum voltage of an 115vac 400 Hz 3 phase motor will run. You can run a single phase motor on a three service but you cannot be run on a single phase.


How do you calculate maximum current of 3 phase motor?

By using a simple formulae: f=np/60 where f= frequency, n is the number of pair of poles and 60 is in seconds that motor is turning. So a 4 pole motor with a frequency of 50 hertz will run at 1500 rpm. By manupilating the formulae: n= 50 multiplied by 60 devided by 2 therefore n= 1500rpm. The formula 120xFrequency/poles gives synchronous speed not actual shaft RPM. Induction motors must run at a certain % slip to obtain torque, so a 4 pole motor running at 50hz would be 120x50/4 = 1500 rpm, at 4% slip (operating speed) actual shaft RPM or rated speed would be 1440 RPM.


Can a 4 Pole 50 Hertz 440 V induction motor run at 900 rpm?

No. With the values given the motor will run at 1500 RPM. RPM = Hz x 60 x 2/# of poles. The only way the motor can be run at that speed is by using a VFD as its source of power.


What is the difference between a one phase and a three phase motor. And if a three phase motor is given a single phase supply will it run or not?

The difference between a single phase and a three phase motor is the amount of power conductors that feed the device. As to the other part of the question a three phase motor will not start or run on single phase. The phase angles on three phase are 120 degrees apart on a single phase system they are 180 degrees apart.


What happens if you under power an electric motor you have a 3 hp single phase motor that requires 39A but your generator only outputs 23.2A?

If you make the connection, the breaker on the generator will trip. The motor will not get up to running RPM. Check and see if the motor is dual voltage. If it is, run it on the higher voltage. This will reduce your run current to about half of what it is on the lower voltage.

Related questions

Can a 415V 3-phase 50 Hz motor run on 380V 3 phase 60 Hz?

Yes, it will run drawing little more extra current in similar conditions. The motor is expected to be running in lesser rpm as well.


What circuit you can use to run three phase motor?

It must be a three phase supply service to run a three phase motor.


How do I determine RPM of a 3v DC motor?

RPM stands for revolutions per minute. This is calculated for different devices and can indicate how fast something is going. For a DC motor, the RPM is calculated by how many times the motor turns.


What is the minimum voltage a 115vac 400hz 3 phase motor will run?

Yes the minimum voltage of an 115vac 400 Hz 3 phase motor will run. You can run a single phase motor on a three service but you cannot be run on a single phase.


Is 3 phase motor run on 1 phase supply?

No. That would be a single phase motor.


How do you calculate maximum current of 3 phase motor?

By using a simple formulae: f=np/60 where f= frequency, n is the number of pair of poles and 60 is in seconds that motor is turning. So a 4 pole motor with a frequency of 50 hertz will run at 1500 rpm. By manupilating the formulae: n= 50 multiplied by 60 devided by 2 therefore n= 1500rpm. The formula 120xFrequency/poles gives synchronous speed not actual shaft RPM. Induction motors must run at a certain % slip to obtain torque, so a 4 pole motor running at 50hz would be 120x50/4 = 1500 rpm, at 4% slip (operating speed) actual shaft RPM or rated speed would be 1440 RPM.


Can a 4 Pole 50 Hertz 440 V induction motor run at 900 rpm?

No. With the values given the motor will run at 1500 RPM. RPM = Hz x 60 x 2/# of poles. The only way the motor can be run at that speed is by using a VFD as its source of power.


Concrete mixer whose motor got following configuration 5.5 KW 380v 1140 RPM 3 phase what is the suitable size of generator to run this motor?

You should get a 3 phase generator that has 8-12 KW. If you had to you could use a 3 phase 5.5-6 kw but it may wear out faster because you are using 100% power. The 3 phase gen will allow you to select 480 volt which can be converted to 380 for the mixer. The rpm of the motor in irrelevant because the generator is the power source in this situation, once the gen powers the motor it will produce 1140 to power the mixer.


What is the difference between a one phase and a three phase motor. And if a three phase motor is given a single phase supply will it run or not?

The difference between a single phase and a three phase motor is the amount of power conductors that feed the device. As to the other part of the question a three phase motor will not start or run on single phase. The phase angles on three phase are 120 degrees apart on a single phase system they are 180 degrees apart.


What is a 3 phase motor that can run with a slip of zero called?

Synchronous motor


What happens if you under power an electric motor you have a 3 hp single phase motor that requires 39A but your generator only outputs 23.2A?

If you make the connection, the breaker on the generator will trip. The motor will not get up to running RPM. Check and see if the motor is dual voltage. If it is, run it on the higher voltage. This will reduce your run current to about half of what it is on the lower voltage.


You have one hp three phase motor where as available power supply is only single phase how can you run this motor?

You will need to install a phase converter or change the motor to single phase. You can find a licensed electrician at www.contraxtor.com