My notes on a Successful setup of FM-50
Some thoughts and observations on installing and using a VFD. In this case a Teco FM-50. I ordered a model 202 which is 220 volt single phase input and 220 volt 3 phase out capable of driving up to 2 HP motors, more accurately capable of up to 7 amps of output.. I am driving a 1-1/2 HP 3 – Phase motor on my RF-30 Mill Drill.
The AC hookup was very straight forward. Points to note are that the 3 phase out MUST be wired directly to the motor (no switches or fuses in those lines) There is no 'neutral' line for 3 Phase hookups, only the 3 phases plus a ground wire. My AC input is a 20 amp 220 volt circuit that I use for my Lathe and Mig Welder. There is NO Neutral in that connection, so my wiring on the VFD input goes to L1, L2 and the Ground Tab. The cord I located to run from the VFD output to the motor had only 3 wires in it, so I ran a separate 14 gauge ground wire to the motor. I also ran the ground wire to the Mill Drill itself. I attached it to the head so that everything is grounded.
My 3 – phase motor initially ran backwards (as is often the case) so I swapped 2 of the 3 phase wires at the motor, which corrects that problem. I powered everything off, and swapped the first and second wires around at the motor to correct the direction of rotation problem
One thing to note is that, when I unplug the VFD, its takes almost 30 second for the display to go off. So I am careful to wait until it is TOTALLY off – dead – blank before I touch the wiring.
If you don't want or need remote controls that's about all you need to do for the setup. There are some programming or settings you can change even without “remote controls” to tailor the VFD to your liking. But you can control the start/stop and speed of the motor right from the VFD front panel.
To ensure that everything was setup from the factory correctly one of the first things I did was do a factory reset on the VFD, function 25 set to 020 for 60 Hertz type power. Many comments on the net indicated that people sometimes had weird symptoms or operation of the VFD until they reset it to factory defaults. I figured it would be best to just start there.
Setting up remote controls for forward – reverse and variable speed can be done with a single switch and a single Potentiometer (often referred to as a 'Pot'). I got my parts from Radio Shack. A Single Pole – Double Throw – Center off switch (SPDT), part number 275-711 was $3.50, I think it was described as a replacement automotive switch. There's no need for heavy duty or anything like that. The switch was cheap and the longer handle – paddle on it seemed to me like it would work well in the shop. I also picked up a part number 271-1715 10k Ohm Linear taper Pot (also $3.50).
There are two possible 'tapers' in Pots. One is called audio taper and the other is Linear. As the name linear implies this type of pot has a straight line increase in resistance as you turn the knob. An audio taper is more like an exponential curve and the increase in resistance is NOT a straight line. IMO the straight line change in speed is what we would want for machine operations.
All of this, the switch and Pot, can be housed in a wall outlet type junction box and it only needs 6 low voltage wires to connect it. For my junction box I choose an old metal one I had lying around because I could stick a magnet on it and then just 'stick' the “control panel” to the mill's head. I used a blank metal cover plate that I drilled out to accept the switch and Pot's shanks. (and you could just as easily use some heavy sheet metal for the cover or the entire box for that matter if you have a bending brake. A plastic cover might not hold up well with the toggle switch snapping back and forth in it..)
I had a nice length of hookup wire (which actually has about 12 wires in it instead of 6) that I used to make the hook up. You can use telephone wire, 'intercom' wire or network cabling. Anything that could be used for low voltage connections. Stranded wire would be more flexible, but the cable I dug up for example is solid wire.
One word of warning on Network cable, it generally has 8 wires in it.. BUT those are configured as “4 pairs” and the color standard in the cable, is Blue – White, Green – White, Orange – White and Brown – White. Depending on the cable vendor – supplier, those 4 white wires may NOT be color coded. They may only be twisted or wrapped with their “paired” wire, the Blue, Green, Orange, or Brown. You might wind up with 4 “white” wires that you can not tell which is which in that type of cable. Before you decide to buy or use some cable you already have it would be advantageous if you can check the end of the cable, or cut into the jacket so you can see how the wires are color coded.
The ideal version of Network cable to use has each of the white wires marked with a colored stripe. One white wire would have a blue stripe, one has green, orange, etc. That way you can keep the wires straight as you're wiring things up. For a basic setup you only need 6 wires, and a network cable usually has 8. Whether the wire is “twisted pair” type wire or not should not matter in this case.
One of the things for me that made this setup VERY confusing were the MANUALS. The versions of the FM-50 manual I downloaded off the net were OLD and do not include some of the diagrams and details that the pocket sized manual that came in the box has. The first additional page or diagram in the pocket manual that I though was useful is a block diagram of the power wiring:
This makes it pretty clear where any breakers, or switches or contactors, etc are to be located in the AC power lines. It also makes it clear that there should be NOTHING between the VFD and the motor.
Apparently the reason for that is because VFD is constantly monitoring the motor and IF the motor is disconnected the VFD will continue to attempt to drive the motor, even though its disconnected and that can FRY the VFD..
In my case I do plan to eventually share the VFD between the Mill and the Metal lathe. BUT, there will be a AC disconnect installed BEFORE the VFD so I can power it completely off. Right now it has a line cord to a 220 – 20 amp wall plug that powers it off. I plan to switch the motor connections with a pair of L14-20 twist lock plugs on the VFD output, in the line to the motors. I will power off, unplug one motor, plug in the other and then power the VFD backup. Thats part of why my “Control panel” is 'mobile'.
I was really confused about the descriptions of the 'multi-function' inputs. I could see the multi-function output described in the pin out diagram. BUT, all of the Input lines are IMO clearly labeled..
Pin 6 is SP1 and Pin 7 is Reset, Right? Well actually NO. Pins 6 and 7 can each be assigned anyone of 6 DIFFERENT functions.
Also pins 3 and 4 can either be setup as: ON/Off for Forward and ON/Off for Reverse OR Pin 4 equals Direction and Pin 3 is Start/Stop. For our use and simplicity in setting this up, the 1st option, 3 = Fwd and 4 = Rev is the simplest setup.
Another page that is missing from the Online and OLDER manuals is the options, or programming chart. This charts lists ALL of the options for all of the 'functions' in ONE PLACE. Notice the 4th column for Functions 19 & 20 as an example.
The chart also makes it clear that the multi-function OUTPUT can be set to 3 different outputs. The multi-function OUTPUT (pin 1 and 2) can be; On when the VFD has power, or ON when the motor is up to Speed, or ON when the VFD has a fault.
Let's get back to the wiring and setup for a plain and simple forward – reverse with variable speed type remote control.
Our SPDT (center OFF) switch needs to have the 12v common (pin 5) connected to the center tab on the switch. Fwd (pin 3) should be connected to one of the outside tabs, Rev (pin 4) needs to be connected to the other tab. The Radio Shack switch has tabs on it that are actually sized so they can take push on – 'FastOn' crimp type connections. If you want to skip the soldering, at least on the switch, you could use crimp type connections here.. Unfortunately the Pot is a solder only type of connection.
When you are setting this up and labeling the switch keep in mind that inside, the switch is connecting that center wire to either one and only one of the FWD, or REV wires. AND, the pin or wire it is connecting to is the OPPOSITE of the direction the handle – paddle is pointing. There is pivot inside the switch and if the paddle is UP, then the switch is connecting the center and BOTTOM wires together.
I think this part of the VFD design is very simple and effective. If you apply the 12V line to FWD (pin 3) the VFD spins up the motor in the FWD direction.. When you remove the 12v signal the VFD goes into STOP or spin down mode based on the setting of function 14 “Stop Method” (the default is a controlled 5 second spin down). In short, connect 12v to pin 3 the mill runs forward, remove it and the mill stops. Connect 12v to pin 4, the mill runs reverse, remove it and it stops. That's why for this setup you MUST use a 'center off' switch.
Variable speed is just about as simple. As the pin out diagram shows, one end of the Pot is connected to pin 8, the other END to pin 10 and the center terminal on the Pot to pin 9.
The wiring diagrams for the nema enclosure versions of the VFD actually show this kind of setup in the manuals (without the pin numbers shown!) I added them to this diagram:
What settings do we need to make our remote control work? After the reset (function 25 set to 020 for 60 Hertz type power.) we need to set:
F 6 = Frequency UPPER limit. The Default is 60 Hz, I like to run the mill up a little higher, so I set it to 90 Hz.
F 7 = Frequency Lower limit. Default is ZERO?? I set it to 15 HZ and this will be the LOWEST speed you can dial with the remote control POT. Turning the pot to the limit of its travel will not go any lower than this setting.
F 10 = Start/Stop control Default is for the KEY pad to control start/stop, we want a remote, set this to 1 (terminal TM2). Which is NOT to describe a pin number, but the Terminal BLOCK. Apparently the AC terminal block is TM1 the smaller control lead block is TM2. Because we LEFT F 3 (operation Mode) at the default setting of 0, pin 3 = Fwd/Stop and pin 4 = Rev/Stop the remote functions as we expect it to.
F 11 = Frequency Control Default is for the KEY pad (again) to control Frequency. We want remote so we set this to a 1, (terminal).
That's all you HAVE to change to set this to work. You can of course play with the Accel and Decel (braking time). You can play with Stop method settings, etc.
If you want you can use more wires and with more switches you can add; Jog, Emergency stop, etc. Any of those 6 options listed for functions 19 and 20.
I did actually add a spring loaded momentary switch to my configuration because I wanted to add an emergency stop. What I found was that the Emergency stop, does the SAME THING as a regular stop if you have controlled Decel mode enabled, F 14 = 0 and the decel time, F 2 set to something low like 1.5 seconds. You may also need to increase the DC braking time to get the VFD to completely stop the motor. But that might also cause an overload if the motor is running at high speed, 90 Hz for example. Then you'll probably need to add a braking resistor.
Based on what I observed I really don't see any difference between Emergency stop and a normal stop. It seems to follow the Stop Method (F 14) setting and the Decel time. As in if I set the Stop Method to coast, then the emergency stop just lets the mill roll to a stop. I'm either missing something as far as the setup goes or Emergency stop is a bit of smoke and mirrors.
Some functions of the FM50 seem a little ODD to me. For example I wired up my momentary switch to pin 6 and set the option to 1 – jog. When I enable the signal nothing happens. The display on the FM50 shows the JOG frequency (F 9) I have set, but the motor does not turn. It seems you have to do a JOG, plus FWD or REV to get that to work. Which is doable with a added Diode but since the FWD and REV lines “start” when you enable them I ASSUMED that the JOG, SP1, and SP2*4 commands or options would do that same. But apparently NOT.
What I DO like about the Vfd is the variable speed. I set my Frequency lower Limit (F 7) to 15 Hz, which is 1/4 of the normal frequency and normal speed. The VFD lets you change the “speed” even when the motor is not running.
My normal mode of operations now are that I do my setup on the mill, I dial the speed all the way down, which only goes down to 15 Hz, and I start the mill motor. At that slow speed I can check touch down, if I am doing some causal work. I can also make sure things are clear. Like the one time I had the face mill over too far and at 15 Hz, the motor just turned until the cutter hit and stopped. I immediately switched off and corrected my mistake, but its a nice check before I really start cutting.
Once I decide the slow speed check is OK, I dial the VFD, with the POT in my “control box” up to the speed I want to run and I start cutting. I mounted my FM 50 up on the wall actually over my lathe, in part because I plan to share it. But I also wanted to make absolutely sure that no swarf or coolants, got inside the VFD.
Overall the VFD is a VERY cool device I hope this write up can help others to complete the setup quicker and with more confidence.
but the lathe is ready to run so i can power and test that.
