Motor Star/Triangle Start

joaco1993

Lifetime Supporting Member
Join Date
Sep 2014
Location
newyork
Posts
237
Hello Everyone,

I have a few questions regarding the start of a motor

The nameplate of the motor is 380/660 delta/triangle 15.1/8.7A

The infeed voltage is 380V three phase.

With that infeed voltage if I wanted to connect the motor directly to the supply i would have to connect it in delta and it would consume 15.1.

However with that infeed voltage, can I do a star/delta start ? even the nameplate of the motor is 380/660 delta triangle ?

Because if I connect the motor in star, the voltage will be 220 and the nameplate doesnt show any 220V.. Will it start anyway (with less torque) or it wont even start ?

thanks!
 
If you connect it in Delta ("triangle"), it needs 380V.

If you connect it in Star (Wye), it needs 660V. 660V is now a valid voltage in some parts of the world, but is not used in North America. For that matter, neither is 380V.

You cannot use that motor at 220V, or rather if you did, it would have only 33% of it's rated peak torque and be very easy to stall unless there was almost no load on it.
 
If you connect it in Delta ("triangle"), it needs 380V.

If you connect it in Star (Wye), it needs 660V. 660V is now a valid voltage in some parts of the world, but is not used in North America. For that matter, neither is 380V.

You cannot use that motor at 220V, or rather if you did, it would have only 33% of it's rated peak torque and be very easy to stall unless there was almost no load on it.

Hi Jraef,

im not planning to use it at 220V. Just to start it in order to consume less current. It will be a Star/delta start.

My question was if in order to do this star/delta start. The motor should be 220/380 or 380/660 or both would work ??

thank!
 
You should ask help from your local motor salesman or Motor Starter salesman, or even any local qualified electrician. Not knowing this fundamental information about star delta starting could mean you do not know some other important information which could make some part of your machines go bang.

Whatever you do though, don't wire a 220/380 motor for 380V star/delta starter.
 
You should ask help from your local motor salesman or Motor Starter salesman, or even any local qualified electrician. Not knowing this fundamental information about star delta starting could mean you do not know some other important information which could make some part of your machines go bang.

Whatever you do though, don't wire a 220/380 motor for 380V star/delta starter.

Hi the motor is 380/660 and the infeed voltaje is 380V three phase

Is ok to do star/delta in this case ??
 
Mr Joaco, please, I am only saying this because I want you and your colleagues to have a safe and happy Christmas, and return home safe and sound to your loved ones. I cannot in good conscious instruct someone over the internet forum how to wire up a motor to 380V. If one of my co workers asked me such a question, I would tell them to go and get the electrician to sit with them at the machine and go through it with them. They would then make sure that all of the electrical safety is adhered to.
 
Mr Joaco, please, I am only saying this because I want you and your colleagues to have a safe and happy Christmas, and return home safe and sound to your loved ones. I cannot in good conscious instruct someone over the internet forum how to wire up a motor to 380V. If one of my co workers asked me such a question, I would tell them to go and get the electrician to sit with them at the machine and go through it with them. They would then make sure that all of the electrical safety is adhered to.

Ok, i have been reading so thanks for nothing Australian jerk.

For other people who might have this question another time:

If the motor is 220/380 you CANT do the start/delta start with 380V infeed because at 220 is should be wired in delta and 380 in star. and if you do the star/delta start is the other way around and you would burn the motor.

The motor must be 380/660 in order to do star delta start with 380V infeed.

it will have less torque and consume less current of course (thats the point of the star/delta start) but its just for the start (5sec lets say) and then delta in 380V
 
If the motor is 380/660 volt then the motor windings are rated for 380volt
Therefore direct on line starting needs to be wired in delta ('triangle'), if wired in star ('wye') then you would be putting 380/1.732 (Square root of 3) across the windings (= 220v).
To run this motor with a star/delta starter you would be required to run it with a line (supply) voltage of 660v


Steve
 
A 380/660V motor is suitable for a star-delta starter with a 380V power line.

Although currently, at least in Europe, the standard voltage is 400V and not 380V and the motors are usually rated 400/690V
 
A 380/660V motor is suitable for a star-delta starter with a 380V power line.

Although currently, at least in Europe, the standard voltage is 400V and not 380V and the motors are usually rated 400/690V

yep you are right,
 
If the motor is 380/660 volt then the motor windings are rated for 380volt
Therefore direct on line starting needs to be wired in delta ('triangle'), if wired in star ('wye') then you would be putting 380/1.732 (Square root of 3) across the windings (= 220v).
To run this motor with a star/delta starter you would be required to run it with a line (supply) voltage of 660v


Steve

I believe you are wrong.. a motor of 380/660 windings should be connected to a 380-400V supply voltage if you want to do a star/delta start. Not 660 supply voltage.

If you want to use supply voltage of 660V you can only connect it in star. If you do star/delta start with 660V supply you will burn the motor.. because in triangle the windings are designed for 380V not 660V.

Correct me anyone if im wrong..

thanks
 
I believe you are wrong.. a motor of 380/660 windings should be connected to a 380-400V supply voltage if you want to do a star/delta start. Not 660 supply voltage.

If you want to use supply voltage of 660V you can only connect it in star. If you do star/delta start with 660V supply you will burn the motor.. because in triangle the windings are designed for 380V not 660V.

Correct me anyone if im wrong..

thanks


You can start some motors in delta directly... not ideal, but for smaller ones it's fairly common to see.
 
You can start some motors in delta directly... not ideal, but for smaller ones it's fairly common to see.

But for other machines such as large centrifugal fans the star-delta starter is not enough and it is necessary to use an electronic starter or a VFD.
 

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