# Another vfd question



## Rangerjoe2 (Apr 14, 2013)

I picked up my lathe last week.  A nice 13" south bend.  It came wired for 480 so I rewired it at the motor for 240.  Pretty simple...there are 3 wires coming from the motor to the panel and into a control box.  They go into terminals marked t1 t2 t3.  Since I'm going to use a vfd I'm thinking I will be unhooking t1t2t3 and wiring them direct to the wires coming from the output side of the vfd.  This will eliminate the components in that box.  All my controls estop, speed pot, for/rev will be wired to the vfd.  Is this correct?


----------



## Bobby Bailey (Apr 14, 2013)

yes
Bobby


----------



## furpo (Apr 15, 2013)

Yes - But
Is there anything useful in the box?
Contactor for E-Stop or ect?


----------



## Rangerjoe2 (Apr 15, 2013)

Hmmm, not sure.  I have everything I need ordered from McMaster Carr.  Vfd will be coming later this week.  Lathe is all leveled up and ready to go just need power!


----------



## twstoerzinger (Apr 15, 2013)

I think Ranger Joe has the right idea. Power wiring from the VFD should go directly to the motor without passing through any switches or disconnects. 

Most VFDs have an input for the E-Stop. On some VFD's you program one of the "configurable" inputs for an E-Stop, others have a specific E-Stop connection.
Depending on the VFD model and configuration, the E-Stop commands the drive to either coasts to a stop, or to decelerate with braking. 

You can also E-Stop by breaking power to the VFD, but you then get a "coast to stop" without the benefit of braking (if the VFD is capable of braking). This method does not depend on the VFD to function as an E-stop.

Most of the VFD manufacturers do not want you to break power between the VFD and motor for fear of damaging the VFD.

Terry S.


----------



## mrbreezeet1 (May 12, 2013)

furpo said:


> Yes - But
> Is there anything useful in the box?
> Contactor for E-Stop or ect?






twstoerzinger said:


> I think Ranger Joe has the right idea. Power wiring from the VFD should go directly to the motor without passing through any switches or disconnects.
> 
> Most VFDs have an input for the E-Stop. On some VFD's you program one of the "configurable" inputs for an E-Stop, others have a specific E-Stop connection.
> Depending on the VFD model and configuration, the E-Stop commands the drive to either coasts to a stop, or to decelerate with braking.
> ...



I think he just meant a button or buttons to use as low voltage control. Button for the e stop, buttons for stop, start,etc.


----------



## Rangerjoe2 (May 12, 2013)

I ended up buying and installing a huanyang 1.5k 2hp 7a vfd from eBay.  I was able to get my speed pot, estop, and for/stop/rev. wired up to the vfd with no problems.  The vfd is connected directly to the motor and all external controls are wired to the vfd via its 24 volt input terminals.  I used a 5k speed pot and programmed the vfd to be adjustable from 30 to 90 htz.  The estop has a 1 no contact and is wired to the DCM and SPL terminal.  I programmed the SPL terminal for estopping.  The for/stop/rev is a 3 position maintained switch with 2 no contacts wired to DCM, for, and rev.  Works like a dream.  Very happy with the set up.


----------



## metalmole (May 12, 2013)

Do you have fuse protection between your VFD and AC breaker ??


----------



## Rangerjoe2 (May 13, 2013)

Yes, power comes from main panel to a disconnect than to vfd.  That allows me the ability to shut down the power to the vfd when not in use.  Has anyone had any experience with load reactors?  I've that a lot of industrial users will install a load reactor between the vfd and motor.  MTE makes one that I could use on my vfd to smooth out the sin wave and reduce harmonic distortion.  From what I understand it conditions the less than perfect 3 phase from vfd.  The motor runs cooler and you don't get the harmonic singing from the carrier wave.


----------



## Codered741 (May 13, 2013)

A Line Reactor does help to smooth out the PWM output of the VFD, into a smoother more traditional sine wave.  They MAY help reduce the "singing" noise from the motor, though you are better off doing that with the PWM frequency in the parameters of the drive itself, if you are able.  

Simply adjust the frequency to something that sounds pleasant, usually the higher the better, though every motor likes something different.  The frequency does correspond to the tone that you will hear, so if your drive is capable of 15kHz+, it is unlikely that you will ever hear it.  (Though it might drive your dog crazy)  As a side note, I find that the higher the frequency the drive is capable of, the higher quality drive you have.  

VFD manufacturers generally do not require a Line Reactor, unless the wire run AFTER the VFD is longer than about 50ft.  This is mainly to reduce the possibility of harmonics developing in the line, which causes motor heating.  

-Cody


----------



## twstoerzinger (May 13, 2013)

I second what Cody is saying. Load reactors are only required when the run between the VFD and to motor gets long (50 ft or greater).
Terry S.


----------



## Rangerjoe2 (May 16, 2013)

I know it's not required for my application, but I'm going to try one of mte 5% impedance load reactors.  My desire will be to smooth the sin wave and allow me to lower the carrier wave freq. on my vfd.  That will allow the motor to run cooler and more efficiently.


----------



## strantor (May 16, 2013)

Rangerjoe2 said:


> I know it's not required for my application, but I'm going to try one of mte 5% impedance load reactors.  My desire will be to smooth the sin wave and allow me to lower the carrier wave freq. on my vfd.  That will allow the motor to run cooler and more efficiently.



Does your VFD log power consumption? I suspect that your reactor won't pay for itself, but it is something that I have always been curious about. Since you've already made the decision to go forward with it, it would be interesting to compare the numbers before installation and after.


----------



## British Steel (May 17, 2013)

Rangerjoe2 said:
			
		

> I know it's not required for my application, but I'm going to try one of mte 5% impedance load reactors.  My desire will be to smooth the sin wave and allow me to lower the carrier wave freq. on my vfd.  That will allow the motor to run cooler and more efficiently.



Another plus with load reactors is the reduction of speed of  voltage rise applied to the motor windings - this makes a major difference to the stress on the insulation, which can be important on older non-VFD rated motors which aren't rated for 700v+ with microsecond rise times as delivered by 400v class VFDs.

You do *lose* that 5% as loss in the load reactors, when considering the sine-wave in the load, but the loss at higher frequencies (eg several KHz switching) is much higher, effectively blocking the fast rising/falling edges that can cause insulation breakdown. The windings won't whine as loudly, either!


----------

