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Thread: VFD outputs

  1. #1
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    Default VFD outputs

    Hi,

    Not knowing any thing about these things we recently purchased one of these units mistakenly thinking we were going to get at least 380 V 3 Phase out. Only got 220 v to dribble out, I revved up my partner ( you have ordered the wrong one ) but the supplier tells us it`s the only one available. Admittedly the motor works ,seems to have some torque but I have my doubts 220 v into a 415 v motor
    Upon reading the hand book a 220 v input single phase input/ 380 volt 3 phase output is available. ( Photo shows 5XXX ) has anybody sighted one of these higher output units?

    John
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  2. #2
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    Did you get a price for a A2-5xxx model?
    They are available but more than double the price....
    Have you switched the wiring of your motor from Star to Delta,?
    Take a photo of the motor label and have a look inside the connection/junction box cover. They often put the connection arrangements for both there. I may be able to help you. If your motor can be changed to Delta, it will have exactly the original power and torque.

    Cheers
    Joe
    Cheers, Joe
    retired - less energy, more time to contemplate projects and more shed time....

  3. #3
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    John

    May I suggest you do a quick google search "Voltage each leg 3 phase". You will most likely get a result with formulas. If my memory from when I learnt this about 30 years ago is correct the voltage will be different for a Delta or Star output. From a quick search it would appear the voltage you are getting is in the ball park.

    I will let you do the calculations and see if what you are getting is correct for how your motor is wound.

    Steve

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    Hi John,

    This is why you will often see that people change the motor wiring from a star connection to a delta one. This very effectively converts a 420 volt star connected motor to a 220 volt delta one.
    Best Regards:
    Baron J.

  5. #5
    BobL is offline Member: Blue and white apron brigade
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    Sounds like you could benefit from reading this
    https://www.woodworkforums.com/f271/vfds-newbies-232742

  6. #6
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    Hi, Thanks for the replys so far, just got back to this project 1.0 KW motor nameplate tells me 415 v. star connected, 220 v delta connected. Trouble is connecting VFD 220 v output to star the motor lacks torque to do the job, connecting VFD to delta configuration it can't handle the starting current. I tried a 2.5 KW VFD still locks out on over current . The motor is a rapid traverse drive on a mill the only time it dies is when lifting the knee, all other drives ok. Something I can live with.

    regards to all

  7. #7
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    With my VFD I can set a number of parameters. One of these is ramp speed. The VFD attempts to spin the motor to operating speed in the time set. Therefore if you have a ramp speed of 2 seconds the VFD tries to get the motor up to that speed in 2 seconds. If you set the ramp speed to 4 seconds it draws a lot less current as it is not trying to spin up so fast.

    Think of it like a car at a traffic light. If you want to hit the speed limit in 2 seconds you need to floor the accelerator but if you are in Sunday morning granny mode you hardly touch the accelerator.

    Steve

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    Thanks Steve, I will try playing around with that setting later, A brain wave come to me around 3.00 AM Try hitting it with a Star / Delta starter Your suggestion first, mine second.

    John

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    BobL is offline Member: Blue and white apron brigade
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    Quote Originally Posted by jcatcmc View Post
    Hi, Thanks for the replys so far, just got back to this project 1.0 KW motor nameplate tells me 415 v. star connected, 220 v delta connected. Trouble is connecting VFD 220 v output to star the motor lacks torque to do the job, connecting VFD to delta configuration it can't handle the starting current. I tried a 2.5 KW VFD still locks out on over current . The motor is a rapid traverse drive on a mill the only time it dies is when lifting the knee, all other drives ok. Something I can live with.
    What was the rating on the first VFD?

    You'd need to be careul using a 2.5kW VFD on a 1kW motor unless the 2.5kW VFD is current limited TO TEH Mx current of teh 1kW motor otherwise you could burn out the motor. This effectively turns the 2.5kW VFD into a 1kW VFD.

    What you are seeing is fairly common for motors that start up under a decent load.

    Johns suggestion of increasing the acceleration time is a good one. What I do in these situations is try an acceleration time of say 10 s and then it decrease by 1 second at a time (9, 8 , 7 etc) and try those and are how low you can go..

  10. #10
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    Thanks Bob,

    I checked out your Video presentation last night ( About my quality at the start got better as it got into it ) anyway when you mentioned the Vector control VFD my ears pricked up but alas that's what i already have. Back to to your comments the motor starts unloaded, its engaged mechanically. The VFD I am using on the 1.0 KW motor is a 1.5 KW unit 7 Amp . I only hooked up the bigger VFD in desperation to see if it made any difference. Both units don't even grunt just lock up with overcurrent indication . Regarding run up time, I was trying to avoid a situation like taking off at the lights in a side valve Morris Minor .

    On another note I was checking out your dust control setup in the video background, nearly identical to mine , I have set up a current sensing relay on the supply to the various machines which bring on the vaccumn unit with run on timer. Any way enough BS

    Thanks again, John

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    BobL is offline Member: Blue and white apron brigade
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    Quote Originally Posted by jcatcmc View Post
    Thanks Bob,

    I checked out your Video presentation last night ( About my quality at the start got better as it got into it ) anyway when you mentioned the Vector control VFD my ears pricked up but alas that's what i already have.
    It's unlikely its configured as a vector drive outta the box. This requries certain parameters to be set and a tune up cycle run to engage the vector drive capacity.

  12. #12
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    Quote Originally Posted by jcatcmc View Post
    Thanks Steve, I will try playing around with that setting later, A brain wave come to me around 3.00 AM Try hitting it with a Star / Delta starter Your suggestion first, mine second.

    John
    Hi John,

    Careful doing that, it could blow your VFD ! They don't like the outputs being switched.
    Best Regards:
    Baron J.

  13. #13
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    Hi,

    With Baron J `s last comment on my mind I thought I would live dangerously and try hooking up a 3 pole changeover switch to the output. One side to the units output , the other a star point and common to U2 V2 W2. U1. V1. W 1. also connected to the VFD output . Worked a treat as long that I didn`t dawdle changing over, machine drives up knee quite adequately I will now look at hooking it up through contactors. As the unit in question is not really a big bucks item if I smoke it to gain a bit of knowledge it gets put down to experience.

    regards to all

  14. #14
    BobL is offline Member: Blue and white apron brigade
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    Quote Originally Posted by jcatcmc View Post
    Hi,

    With Baron J `s last comment on my mind I thought I would live dangerously and try hooking up a 3 pole changeover switch to the output. One side to the units output , the other a star point and common to U2 V2 W2. U1. V1. W 1. also connected to the VFD output . Worked a treat as long that I didn`t dawdle changing over, machine drives up knee quite adequately I will now look at hooking it up through contactors. As the unit in question is not really a big bucks item if I smoke it to gain a bit of knowledge it gets put down to experience.

    regards to all

    I don't understand the point of doing this with a 240V VFD. If the motor is set on delta and it works, why not leave it on delta?
    Running a 415V motor on star using 240V 3P only allows a motor to ever develop half the power.
    Using an underpowered motor long term leaving can damage the motor.

    The delta/star starts are for 3P motors connected to 415V - they start as delta generating double power to overcome load/inertia and then switching to start develops normal power.
    When hooked up to 240V 3P the switch is from normal to half power.

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    Quote Originally Posted by jcatcmc View Post
    Hi,

    With Baron J `s last comment on my mind I thought I would live dangerously and try hooking up a 3 pole changeover switch to the output.
    I think that is safe, as long as you never switch it over when the VFD is powered up!

    Byron was saying the output electrics expect to be wired up to a load.
    If you randomly disconnect one when it is powered up, it can let the smoke out.

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