Spindle speed low after 3phase to single phase conversion

[dakotalarry]

I am attempting to covert a 1993 Fadal 3016 with a Baldor Sweodrive 712 series from 3phase to single phase. I have switched transformers (816 - 814). and from the Fadal diagrams for the T-814, I believe I have everything properly wired (as far as the T-814 goes). Everything appears fine when I power up. I am able to jog the axis into position. BUT, when I try to run the spindle i.e. M3S3000, the spindle runs very slow (maybe 30 RPM). Smooth but very slow. I am hoping that as a newbie, I have done something stupid and I am willing to be used as a bad example of not reading everything I should prior to attempting such an endevor. But, I would rather start making chips than try to find the document that explains what I should have done. Please, if you can help me get my machine running I would very much appreciate it.

dakotalarry

[jalessi]

Dakotalarry,

You may need to purchase a single phase input VFD.

Jeff...

[carbidecraters]

Originally Posted by jalessi Dakotalarry, You may need to purchase a single phase input VFD. Jeff...

That is not accurate the sweo drive can be powered by single or three phase.

[Easydad]

Depending on the hp of the motor, you need to use a vfd that fits the hp. I use a GPD 315 for my 7hp perske. The problem when you use 240v converted to 3phase, you loose hp. If your spindle is rated for a higher voltage (mine is 480 normal) the rated hp is now 5hp. The vfd does not make true ac. It makes chopped dc in three phases, I clean the chopped dc with an MTE Series Line Load Reactor LC coil before sending to the perske. Then for safety sake, I limit the speed of the motor to 90% of max, so the 300hz frequency becomes 270hz max. which is 18,900rpm instead of 21,000. When I cut acrylic, the edges will cut your fingers if you aren't careful :-) There is nothing like a Perske!

[jalessi]

Carbidecraters,

Please post the single phase wiring diagram for the Sweodrive.

I was guessing the drive may not work with single phase.

After thinking about this for a few more minutes, I started to wonder if the drive may only be working on one leg.

Thank You

Jeff...

[carbidecraters]

Alot of guessing in this thread but no real answers yet.

T-814 can be used with either single phase or three phase. Its wiring diagram is noted in all manuals from 1990-1997 and possibly later.

Depending on the hp of the motor, you need to use a vfd that fits the hp. I use a GPD 315 for my 7hp perske. The problem when you use 240v converted to 3phase, you loose hp. If your spindle is rated for a higher voltage (mine is 480 normal) the rated hp is now 5hp. The vfd does not make true ac. It makes chopped dc in three phases, I clean the chopped dc with an MTE Series Line Load Reactor LC coil before sending to the perske. Then for safety sake, I limit the speed of the motor to 90% of max, so the 300hz frequency becomes 270hz max. which is 18,900rpm instead of 21,000. When I cut acrylic, the edges will cut your fingers if you aren't careful :-) There is nothing like a Perske!

The above statement doesnt apply to this issue. Sorry if I sound testy I havent slept in 49hrs

[scadvice]

If you have not already checked the voltages on each leg you need to do so.
Check that the voltages that are coming into the transformer on each leg, next check the output voltages to see that they are what they are suppose to be. If it were me i would then check the voltage drop going to the VFD while the spindle is on. A couple of questions: Before you bought the machine did you see it run and was it running on? 3 phase and at what voltage? I agree with 'carbide' (again) it has to be the transforemer wiring or some other thing assoc. with power going to the VFD.... not the VFD.
Steve

[carbidecraters]

The machine was running on 3 phase before line voltage of 210 with a 816 transformer. He has the correct 1170-0 board but has not verified input voltage (IIRC). The single phase wiring instructions are very vague in the Fadal manuals and you have to crossreference the 3 phase wiring diagram.



There is a suggestion in the manual that on SWEO drives that tells you need to wire L2 and L1 of the input to get the fan to run on the SWEO. This in itself is confusing. The Baldor book says L2 and L3 must be tied together and his electrician says "I hope you didnt wire L1 and L2 together". I really think Larry is not working with the sharpest of pencils in North dakota. Logic tells me L1 and L3 are the same voltage to the VFD because as we know in three phase the line voltage would have to remain consistant. The electrician who stopped by told him if he hooked up L2 and L3 he would complete a circuit...rediculous. Something is definately wrong with the wiring.

[dakotalarry]

Actually I did check the input voltages and currents. I don't recall exactly what the voltages were but they were very unalarming.. If I remember right 240 and 238. The current was about 4.5 amp with the machine running without the spindel on and about 5 amp with the spindle turning.

[dakotalarry]

I was thinking about what the electrician said about L1 and L2 and occured to me that he probably though I was talking about the L1 and L2 coming out of the fuse box. The two hot legs into the T-814.

[HuFlungDung]

What does the schematic for the input hookup to the VFD show? Only connections to two inputs? IIRC, some VFD's require one of the single phase hot wires to be split on two inputs to the VFD, which is the same as tying L2 and L3 together. But the schematic should show this.

What is providing the 0-10v input voltage command signal after this changeover? Is that working properly?

[carbidecraters]

Larry I think you will have to go through all the wiring on the T-former and also get that L1 and L2 together like the manual suggests and then check again. Something is just a little off and I thought you had hooked L1 and L2 together and got the same issue. Check those numbers on the t-former and check the wires...double check triple check and mark that off the list.