Another vfd question

Rangerjoe2

Rangerjoe2

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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?
 
Last edited:
Yes - But
Is there anything useful in the box?
Contactor for E-Stop or ect?
 
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!
 
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.
 
furpo said:
Yes - But
Is there anything useful in the box?
Contactor for E-Stop or ect?
Click to expand...


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.

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.
Click to expand...

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.
 
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.
 
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.
 
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
 
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