# Teco Variable Frequency Drive: Model JNEV-203-H1



## tblank

Thank you for your insightfull review. Been wondering about these for awhile. Seems a good price as well comparatively.


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## Brewster

Yes VFD is the way to go.My friend has a metal working 3 phase band saw which he installed a Vfd.He has used it for several years and gives excellent performance.There are still a lot of 3 phase motors out there that are relatively inexpensive that can be converted to woodworking machinery without being machine specific . thanks for the insight. Bruce


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## Bertha

Great review! Takes a bit of the mystery out of these for me.


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## sikrap

I have a similar VFD for my 3 phase Delta jointer and its great. One other benefit is that if you install a twist lock plug somewhere between the machine and the VFD, you can start looking at other 3-phase machines and they are generally MUCH less expensive than single phase.


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## donwilwol

So could you wire multiple machines, or would you have to unplug and plug the different machine into it?

Thanks for the review. I've always tended to avoid 3 phase machines for the obvious reasons, although they seem not so obvious now.


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## MedicKen

I absolutely love 3ph machines. I have 3 VFD's now and they work wonderfully. The best application is for either a drill press or lathe where you can utilize the variable speed capabilities. I dont think I will ever go back to single phase. Nice review of the VFD, all of mine are the entry level FM50's and I have not had 1 issue with any of them. I have also found that factorymation.com has a little better pricing than delaerselectric.


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## barecycles

MedicKen: I agree. It makes me want to go out and buy a big honkin' lathe so I can fully use the capabilities of the VFD

Don W: The short answer is yes and no…sorry, I know that's vague. Below is what the guys over at OWWM say about it:

*If you mean turning on and off two motors at the same time, the answer is yes. Just hook them up in parallel.

If you want to have two or more devices turn on and off at will then the answer is maybe.

I wrote a PLR (Programmable Logic Relay) program earlier this year so that one could safely share a VFD between machines. I was done in about 4 hours.

The constraints to switching a VFD's output are formidable when one tries to use just contactors and switches to handle the switching. Here are the constraints as I see them.

The output of the VFD must be connected to the motor before the VFD is told to turn on the motor.
The VFD must be told to turn off and braking completed before disconnecting the motor from the VFD.
Once a motor or motors are selected and the VFD turned on, no other motor may be connected to the VFD's output. In other words a lockout must occur.
The fwd/rev, start/stop, and variable speed controls must be switched from station to station.
*


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## b2rtch

I do not mean to hijack this post but be careful before you go buy a VFD.

I wanted to do the same thing at home but at work just about all our equipment is on VFD and I was told that all motors do not work properly with a VFD, they must be inverter duty if not they will burn out.
Because, in addition to other things, with a VDF a normal electric motor can be run very low rpm and at full load, it does not get enough cooling.
I hope this help.

From : 
http://motors.automationdirect.com/Information/compare.html

How to choose a general purpose motor vs. an inverter-duty motor
General purpose motors have been around for many years. They are the workhorse of almost every industry. An inverter-duty motor is a much newer concept that became necessary as motors began to be driven by VFDs (inverters or AC drives). An inverter duty motor can withstand the higher voltage spikes produced by all VFDs (amplified at longer cable lengths) and can run at very slow speeds without overheating. This performance comes at a cost: inverter-duty motors can be much more expensive than general purpose motors. Guidelines for choosing an Ironhorse general purpose motor vs. an inverter-duty motor are given below. If your application falls within the guidelines below, there is no need to apply an inverter-duty motor.
NOTE: Marathon inverter-duty motors have limitations as well. Please see the Marathon section for more details.
Background: AC motors can be driven by across-the-line contactors and starters. The electricity sent to the motor is a very clean (true) sine wave at 60Hz. Noise and voltage peaks are relatively small. However, there are drawbacks: the motors can only run electrically at one speed (speed reduction is usually handled by gearboxes or some other, usually inefficient, mechanical means) and the inrush of electrical current (when the motor is first turned on) is usually 5 to 6 times the normal current that the motor consumes. The speed reduction apparatus is expensive and bulky, and the inrush can wreak havoc with power systems and loading (imagine an air conditioning system in an old house - when the compressor kicks on, the lights dim; now imagine the same circumstances with a motor the size of a small car).
Note: The following discussion applies only to 3-phase motors.
Enter the VFDs (variable frequency drives):
Drives were introduced to allow the speed of these motors to be changed while running and to lessen the inrush current when the motor first starts up. To do this, the drive takes the incoming 60Hz AC power and rectifies it to a DC voltage. Every drive has a DC bus that is around 1.414 (sqrt of 2) * incoming AC Line Voltage.
motor base chart

This DC voltage is then "chopped" by power transistors at very high frequencies to simulate a sine wave that is sent to the motor. By converting the incoming power to DC and then reconverting it to AC, the drive can vary its output voltage and output frequency, thus varying the speed of a motor. Everything sounds great, right? We get to control the frequency and voltage going out to the motor, thus controlling its speed.
Some things to watch out for:
A VFD-driven general purpose motor can overheat if it is run too slowly. (Motors can get hot if they're run slower than their rated speed.) Since most general purpose motors cool themselves with shaft-mounted fans, slow speeds mean less cooling. If the motor overheats, bearing and insulation life will be reduced. Therefore there are minimum speed requirements for all motors.
The voltage "chopping" that occurs in the drive actually sends high-voltage spikes (at the DC bus level) down the wire to the motor. If the system contains long cabling, there are actually instances where a reflected wave occurs at the motor. The reflected wave can effectively double the voltage on the wire. This can lead to premature failure of the motor insulation. Long cable lengths between the motor and drive increase the harmful effects of the reflected wave, as do high chopping frequencies (listed in drive manuals as carrier frequencies). Line reactors, 1:1 transformers placed at the output of the drive, can help reduce the voltage spikes going from the drive to the motor. Line reactors are used in many instances when the motor is located far from the drive.

Effect of a Line Reactor on the Waveform

In summary, general purpose motors can be run with drives in many applications; however inverter-duty motors are designed to handle much lower speeds without overheating and they are capable of withstanding higher voltage spikes without their insulation failing. With the increased performance comes an increase in cost. This additional cost can be worth it if you need greater performance.


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## klassenl

Yep, technology is great.

You don't need and enclosure for it, but the code but would ask that all wiring that is not contained within a cable sheath, raceway, etc. to be in a metal box approved for such a purpose. However, if you saw my shop you wouldn't think that it belonged to an electrician that was familiar with code.

Be safe.


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## barecycles

Bert makes a valid point about speed and the cooling aspect of the motor. The Baldor motor on this Unisaw was designed to spin at 3450 RPM, 60 Hz for a reason. I refrain from increasing the speed for fear of ruining the bearings at higher speeds. Likewise, running too slow places the motor in jeopardy of overheating. According to the experts (I use that term very loosely) I hang around, these AC motors should never be run at less than 75% or more than 125%. The VFD is set at 60 Hz to run my saw and I don't see any reason to deviate from that.

Now, there is another aspect of bearing failure that can occur in a VFD driven motor. The voltages that can build up on the motor shaft will likely be discharged to the bearings causing small pitting that progressively gets worse over time. I'm not familiar with this situation happening on a VFD controlled Unisaw motor but I have experienced it elsewhere.


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## hhhopks

Thanks for the education and enlightenment.
It is amazing how computer/electronics works.


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## cigale

Hello, a new question for an old topic.

As I just ordered a VDF, I was wondering if the motor needs to be grounded aslo?
I see you only connect the 3 phase cables to the motor.

Greetings


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## vweaver

Now that you've had 3 years (? assumption) under your belt, do you still feel the VFD was(is) the way to go?


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## barecycles

vweaver: Yes, the VFD is still going strong, I have been using it regularly and I have not had any issues with it. Now, other things in my shop have bit the dust but not this item.


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## ControlsGuy

Hi Guys. A friendly reminder.
When mounting these drives, be aware of the National Electric Code as well as all State and Local Electrical Codes.
Depending on those requirements you may be required to mount the drive in an enclosure, and meet requirements like UL and/or ETL.
Some of those requirements are also going to state that you have both short circuit and overcurrent protection for your motor. If using a drive, your drive can be programmed to meet the overcurrent requirement, but you will still need to provide fuses or circuit breaker to meet short circuit requirements.
Depending on where your motor is in proximity of your drive (distance and line of site), you may also need a local disconnect by the motor in addition to the main disconnect or beaker for the drive.
Also I know you guys work with wood so therefore you want to use wood to mount the drives and their protection devices and wire, but you need to be thinking none flammable materials like metal enclosures and metal back panels. If you have ever seen the capacitors go on a drive, or have an ARC Flash at your drive panel your going to understand why. Even if your local code allows mounting the drives open and to a wall, if you have an Arc Flash or Capacitor go your enclosure may not just save you but your building from burning down as well. Enclosures are also to provide protection against moisture, water, oil, as well as dust and even in a clean environment I have seen those issues where you would think there would not exist any. Wrapping your wires around wood and mounting your disconnects using wood standoffs is a really bad idea. The extra couple hundred dollars for an proper enclosure and back pan is worth it in many ways. And remember, be careful out there.


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## barecycles

Thanks Control Guy…all valid points and should be considered when setting up a system like this.


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