star ? delta?

[smith1990]

Hello can you tell me the best way to tell wether to connect the motor in delta or star. If the name plate has a star and a delta symbol on it .

 

[LeeH]

Look at the voltage on the plate. Simples.

 

[Knobhead]

240v y
415v ∆

 

[smith1990]

But what if it states both voltages i. E it says 230 v and 400v on the name plate how would i no which one i using

 

[telectrix]

sounds like you have a dual voltage motor. if supplying @415V think about it. in star, you'll have 240V across each winding ( line to star point) but if you connected it in delta, then you get 415V across each winding. goes like stink but won't last 5 minutes.

 

[Knobhead]

The higher voltage will be star for the reason Tel gave.

 

[tvspark]

Hi, if it's bog standard 3 phase motor, then normal running will be delta.
Star is used if the motor has a heavy load to get moving. Star configuration limits the current drawn so you don't blow the fuses.
It will be in star for 5 to 10 seconds then switch over to delta.
If there is no heavy load, then delta only is fine.
The speed of the motor is governed by the supply frequency and the number of poles in the motor. So it should be about 3000 rmp whether in star or delta.
Hope this helps.

 

[BeerSpark]

sounds like you have a dual voltage motor. if supplying @415V think about it. in star, you'll have 240V across each winding ( line to star point) but if you connected it in delta, then you get 415V across each winding. goes like stink but won't last 5 minutes.

Wouldn't want him to get the impression that it will run faster if connected in Delta. Chiefly, it's number of poles and frequency that determine speed! Ns = (120 x f)/p :smilewinkgrin:

 

[Bobster]

Torque will also be effected.

 

[Besoeker]

Wouldn't want him to get the impression that it will run faster if connected in Delta. Chiefly, it's number of poles and frequency that determine speed! Ns = (120 x f)/p :smilewinkgrin:

But it will be faster to stink.....if it's 400V across a 230V winding.

 

[Besoeker]

Torque will also be effected.

With the correct voltage applied for the given configuration, the motor will develop the same torque for star and delta.

P=Tω
ω is the rotational speed in radians/sec

Don't you just love the simplicity of SI units.....
I wonder how many here are old enough to remember 33,000 ft-lb/minute?

 

[jamie-spark]

sounds like you have a dual voltage motor. if supplying @415V think about it. in star, you'll have 240V across each winding ( line to star point) but if you connected it in delta, then you get 415V across each winding. goes like stink but won't last 5 minutes.

Tel

Voltages never ever ever creep up over 230 and 400 v

 

[Knobhead]

Hi, if it's bog standard 3 phase motor, then normal running will be delta.
Star is used if the motor has a heavy load to get moving. Star configuration limits the current drawn so you don't blow the fuses.
It will be in star for 5 to 10 seconds then switch over to delta.
If there is no heavy load, then delta only is fine.
The speed of the motor is governed by the supply frequency and the number of poles in the motor. So it should be about 3000 rmp whether in star or delta.
Hope this helps.

I notice this is your first post so I will give you a tip.

Read the OP (opening post) first.

We are talking of dual voltage not Y∆ starters. Added to which I certainly wouldn’t be considering Y∆ for a high inertia load.

 

[tvspark]

I notice this is your first post so I will give you a tip.

Read the OP (opening post) first.

We are talking of dual voltage not Y∆ starters. Added to which I certainly wouldn’t be considering Y∆ for a high inertia load.

Hi Tony, Having re-read the OP, he makes no mention of dual voltage.
It's your post (post number 3) that mentions dual voltage.

And I don't believe 240 volt 3 phase systems are very common.

All the best

 

[LeeH]

Hi Tony, Having re-read the OP, he makes no mention of dual voltage.
It's your post (post number 3) that mentions dual voltage.

And I don't believe 240 volt 3 phase systems are very common.

All the best

They are not, but I come across plenty of single phase VSD's which require the motors to be 230 3 phase.

Also the majority of motors I have worked with 3-4KW and under need to be in star. Telling the OP to use delta could end in tears.

OP, like I said just look on the plate, it's that easy. It will state the voltage on the plate!

 

[LeeH]

240v y
415v ∆

Tony, you've forgotten more the I'll probably ever know about motors. Is that a typo?

 

[Darkwood]

Hi Tony, Having re-read the OP, he makes no mention of dual voltage.
It's your post (post number 3) that mentions dual voltage.

And I don't believe 240 volt 3 phase systems are very common.

All the best

The OP doesn't have to mention the term duel voltage as the nature of the question gives us this info with its star or delta arrangement and 2 voltages on the plate.

If DOL and using a duel voltage motor then usually star connected as already pointed out

Star 400v
Delta 230v

A lot of motors now are run through VFD's and can be giving out a common voltage of 3ph up to 230v off a 1ph supply so where you have a duel voltage motor that most European 'Bog Standard' squirrel cage motors are then it will be connected in delta.

If the motor is designed for Star/Delta starting then it will usually have the windings higher rated -

Star -690v
Delta- 415v is a common setup ...

You 'Bog Standard' motor is usually 4-pole 1500rpm which is a good balance of torque and speed as your 2 pole motor 3000-rpm sacrifices torque for the extra speed but both are still common

 

[Patrick Griffin]

Dual voltage motors have windings rated at 230 volts. If the supply voltage is 400v you connect in star, if the supply voltage is 230 volts you connect in delta. The reason for this is when you connect in star you are connecting across two windings hence 400 volts. With delta you connect across one winding hence 230 volts.

With this motor if you put 400v in delta you will burn out the motor. If you put 230v across the windings in star you will only develope one third of its power and will stall under load.

 

[telectrix]

Dual voltage motors have windings rated at 230 volts. If the supply voltage is 400v you connect in star, if the supply voltage is 230 volts you connect in delta. The reason for this is when you connect in star you are connecting across two windings hence 400 volts. With delta you connect across one winding hence 230 volts.

With this motor if you put 400v in delta you will burn out the motor. If you put 230v across the windings in star you will only develope one third of its power and will stall under load.

exactly what i said in post#5.

 

[Darkwood]

To be totally correct we must not assume the OP has a duel voltage motor without confirmation it could be many variants of motor configs that are nothing to do with duel voltage when connecting in star or delta and could be for example a 'consequent pole' motor where the connection determines the speed High or Low although in the scope of things its unlikely the OP will have stumbled on this kind without yrs in the business.

As he later asks the question 'what if the plate has 2 voltages on it' we can deduce he's more than likely looking at a duel voltage motor but not necessarily 400 -230.