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### Author Topic: VFD and motor voltages  (Read 16792 times)

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#### NosmoKing

• 238
##### Re: VFD and motor voltages
« Reply #20 on: June 15, 2011, 04:04:19 PM »
So are there 240V single phase input VFDs that will output 415V three phase? I have never seen one but again my experience with VFDs is limited.
Hood

Never ever  seen those listed, only the 120v input.
N.

#### Hood

• 25,846
• Carnoustie, Scotland
##### Re: VFD and motor voltages
« Reply #21 on: June 15, 2011, 04:34:50 PM »
Ok so safe to say that for Katoh he will have to get a motor that can take 240v, whether thats one thats only 240v or a dual volt motor.

Hood

#### Katoh

• 274
##### Re: VFD and motor voltages
« Reply #22 on: June 15, 2011, 07:36:08 PM »
Having said that I have never seen a VFD that outputs a higher voltage than the input voltage and for the single phase 240v input ones I have never seen one capable of outputting more than 240v three phase.

What of the 120v 1 ph input models that run a 240v 3ph motor?
Agreed they are in the lower HP range.
You may not run across them in the UK due to no 120vac generally.
N.
Exactly to my point Nosmoking, If in the states you have VFD with 110v input to drive a 220v 3ph motor then it only make sense that a 240v input should drive a 415v motor.
I'm going to work now, so I am going to hassle the electrician again that works there.
Cheers
Katoh

#### NosmoKing

• 238
##### Re: VFD and motor voltages
« Reply #23 on: June 15, 2011, 08:19:38 PM »
Quote
Exactly to my point Nosmoking, If in the states you have VFD with 110v input to drive a 220v 3ph motor then it only make sense that a 240v input should drive a 415v motor.
The 120v in 240v out are specifically designed that way, you may be out of luck finding a 240 in 415v out, unless designed that way.
I have never ran across one.
N.

#### Katoh

• 274
##### Re: VFD and motor voltages
« Reply #24 on: June 16, 2011, 03:00:00 AM »
Gentlemen
After a full on day of conversing with our local sparky, we both ended up totally confused on the issue at hand. After now another 3 hours wasted on google and numerous phone calls around the country, we may have a little light at the end of this subject. From what I have been able to understand from what I have read, the following happens.
Input into the VFD  = 240v single phase
output is  240v 3 phase (240v per phase if taken to earth or back to neutral) but still only 240v across phases.
A 415v 3phase motor if the wirings are in star or wye configuration will work fine if wired to delta on the inputs.
Motors that are internally wired delta will need a 415v input across actives or can be run with a Wye - delta starter, these are more likely in very large motors.
I would love for someone to confirm my findings!
Cheers Katoh
Cheers
Katoh

#### Katoh

• 274
##### Re: VFD and motor voltages
« Reply #25 on: June 16, 2011, 09:26:54 AM »
Gentlemen
Just to add to my last post if there is anyone else needing the same information, a little more reading and some more information.
To carry on from before, if your motor has 6 terminals were you connect your wires too the motor your job is easy, and your motor will run happily with the vfd. Refer http://www.backsaw.net/pics/MotorWiring.jpg for wiring diagram.
If you only have 3 terminals you may then have to do some internal works to the motor. Again this is only for motors that are wound in wye or star configuration and yes they are 415v 3 phase motors.
99% of motors under 5kw will be wye or star not delta wound.
For the adventuress here is a link to another forum were it is described how to rewire it yourself.
http://www.woodworkforums.com/f189/finally-finished-my-260-a-116004/
For the less I'm sure it would be a cheap exercise to have it done. I will find out soon.
Cheers
Katoh
« Last Edit: June 16, 2011, 09:28:27 AM by Katoh »
Cheers
Katoh

#### BR549

• 6,925
##### Re: VFD and motor voltages
« Reply #26 on: June 16, 2011, 09:40:26 AM »
I think you have seriously over complicated the process(;-)  3p motors have 3 phase wires to hook to. abc sets the phase rotation or the direction the motor will run.  Dual voltage motors HAVE a set of extra leads as well that allow you to put the windings in series or parrallel. high voltage or low voltage.

Match the VFD output rated voltage to the motor rated voltage and you are good to go. That is all there is to it. If your base rotation is backwards then swap any to input leads to the motor.

(;-) TP

#### Katoh

• 274
##### Re: VFD and motor voltages
« Reply #27 on: June 16, 2011, 10:59:11 AM »
TP
I realise that I may have made things more complex, and yes you can get motors that have both 240/415 or basically duel voltage input.
At least now we have basically clarified that from a VFD input of 240v single phase then you have to wire it to the 240v input or delta winding on the motor. Not to confuse things further I did find tonight a VFD 240v input single phase to 415v 3 phase output. But for 400 pounds they can keep it.

I am looking into using a motor which is not duel voltage is just simply 415v 3phase star or wye connected in the windings for the lathe. I would just like to say that this motor can be used with the 240VFD output, it just needs a bit of re-wiring as stated earlier.
This has been a real learning curve for me and now I know basically what will and wont work.
Katoh
Cheers
Katoh

#### Katoh

• 274
##### Re: VFD and motor voltages
« Reply #28 on: June 16, 2011, 11:52:28 AM »
One Other question on the same subject. With a single phase input into the vfd do you need to install a line reactor and EMI filter and how to you wire a single phase into a 3 phase line reactor?
Thanks
Cheers
Katoh

#### BR549

• 6,925
##### Re: VFD and motor voltages
« Reply #29 on: June 16, 2011, 11:58:58 AM »
YOu really need to get the Y or delta out of the thought process.  You have 3 leads abc you do not have a neutral in most cases(never seen one here).  HOW the motor was WOUND is irrelevant to your process.

The hook up is abc  voltage is measured phase to phase. A voltage check phase to GRND is useless info in the case of the motor performance. You have to match the VFD output to the motor input requirement.

Keep it in that thought process and you are good to go.

Just a thought(;-)TP