Thread: Power supply for 3-phase DE when using VFD

Originally Posted by John Samuel

Ahhhh ...

Are you suggesting I should actually take care to read a thread before responding?

Welllll . . .

Actually I'm not so crash hot at doing that either.

John and BobL who cares what you guys write is always interesting anyway. It is an excepted fact that real men do not read instruction books so this is just an extension of that

Shedman

Hot damn, BobL ...

We are officially Real Men.

I can't wait to enlighten SWMBO!

Originally Posted by John Samuel

Hot damn, BobL ...

We are officially Real Men.

I can't wait to enlighten SWMBO!

I have recently started to read instructions even if it is only to be able to tell SWMBO that I have and generally demonstrate it in some way or other - like relating a superfluous fact or two about said item.
SWMBO is impressed by the this.

John, this is a new build from scratch on an empty block. My wife needs 3-phase for her pottery kiln - she has used a single phase 15A or 20A circuit for many years, but is significantly restricted in kiln size and desperately wants to fire larger sculptural pieces. So, to run another 10m to my shed ... well you only cry once, and then there are no equipment limitations, now or in the future.

Chris, we discussed this at Brett's GTG in February. The impression I got from you was that the variable frequency, the ability to run at 60Hz (I have no plans to run any higher), was a very significant benefit of a VFD, even if utility 3-phase were available. Effectively, you got a lot more DE for little extra cost.

As Bob wrote, motors have run for decades without soft start, but if the facility is there, why not use it. It can only reduce motor wear, even if probably very insignificantly.

So, in summary: 3-phase hard-wired to a VFD, supplying 415V to the motor; ability to run DE faster; remote control by the saw, as DE will be outside the shed as per Bob's recommendations.

Mark

I picked up a 240V 3 phase 4HP motor today for $50. given I only have 240V in the shed that's one I will definitely be using a soft start on.

Originally Posted by markkr

The impression I got from you was that the variable frequency, the ability to run at 60Hz (I have no plans to run any higher), was a very significant benefit of a VFD, even if utility 3-phase were available. Effectively, you got a lot more DE for little extra cost.

I have come to this thread late but as I am just assembling my CVMAX I have started trolling for installs. I keep coming across the figure 60Hz, but the motor that came with mine is a TECO three phase rated at 50Hz. Where does the extra 10Hz come from or does his only relate to the US Leeson motors?

Originally Posted by Soredust

I have come to this thread late but as I am just assembling my CVMAX I have started trolling for installs. I keep coming across the figure 60Hz, but the motor that came with mine is a TECO three phase rated at 50Hz. Where does the extra 10Hz come from or does his only relate to the US Leeson motors?

to get 60 Hz you need a VFD which allows generates a Frequency anywhere from 0 to ~400 Hz.
Not that I recommend running the motor at anything even close to 400 but you should be fine with 60.

The motor rating is usually for current/Voltage at a specific frequency. Changing the frequency from 50 to 60 will increase the current but most 3 phase motors can handle this amount of change

Hi Bob, electricity is strings and mirrors to me mate. I have purchased the VFD to go with the unit, I will be running 15A in and whatever comes out...comes out. I will be paying a sparky for that bit and no error.

Originally Posted by Soredust

Hi Bob, electricity is strings and mirrors to me mate. I have purchased the VFD to go with the unit, I will be running 15A in and whatever comes out...comes out. I will be paying a sparky for that bit and no error.

Yep - best leave it to the sparky.

Originally Posted by Soredust

Hi Bob, electricity is strings and mirrors to me mate. I have purchased the VFD to go with the unit, I will be running 15A in and whatever comes out...comes out. I will be paying a sparky for that bit and no error.

It pays to be alert.

Like you, as an electrician I would make a great cricketer. I paid a sparky. He left the motor connections set at star (415V) rather than delta (240V). He also left the motor spinning in reverse ... after I had told him which way it should spin.

Yes ... he was not a terribly bright sparky, despite years of industrial experience. Do your own checks of these things.

These things were easy to fix, thankfully.

One more thing. I made up an RF remote so I can turn on my CV 1800 from anywhere in the shed, and love it to death. You might like to consider a similar set up. I bought a remote with 3 GPOs. One operates the CV, one operates the shop vac I have mounted outside the shed and one is spare.

Originally Posted by John Samuel

Do your own checks of these things.

Do my own checks? I wouldn't know what the hell I'm looking for. I dug out the manual for the VFD I received from Stephen and it may have well been in a different language, it doesn't help that it has been translated to English, and I quote..."When unpacking, if control system with water, parts missed or component damaged are found, do not install".

Honestly, I will need to ring around and find a sparky who is conversant with this type of system.