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How to wire limit switches and estop on a BP mill with a VFD


Apr 25, 2018
I am new to this forum and the answer to my questions my be here (somewhere) but I haven't found them. I have purchased a BP mill with an Anilam control. I have single phase 220v available and need to convert it to 3 phase for the 2 HP spindle motor. There are 2 wires coming from the controller to the electrical cabinet with the incoming power. Currently the wires open the power contactors when a limit switch or the Emergency Stop has been hit. I know I can't just use the contactors since they would be between the VFD and the motor.
What are some ways to accomplish the same thing using a VFD?
Are there some models or brands of VFDs that are more suited for use with a controller than others?
Are there VFDs with ESTOP capability?
First of all, welcome.
Second, we don't know what your level of expertice is for wiring and electrical. If it's very basic, you'll need to be adding pictures for us to be of much help.

Probably the most popular VFD out there is the TECO FM-50. I run several. To be honest, the manuals for all of them are terrible. There are terminals to put an E-stop on the VFD, and that will require some parameter programming of the VFD. You're also going to need the model of the control that you have. Does the control work?

I'm just sitting here thinking that IMO, this type of a job is probably over the skill level of most of the people that I know. Probably won't be an easy job. Also, have you ever ran a CNC mill before? AFAIK, there is no longer any support for Anilam controls and if there is a problem, most are replaced with a PC base controler.

Get us some more information and you'll get plenty of help.
There are different ways to rig up an E-stop on a VFD. One way is to run a button with two wires to discrete inputs on the VFD that are programmed to stop the VFD output - but that method does not actually physically remove the power from either VFD input or output to the motor. Since this method depends on the VFD's proper functioning at all times in order to work, I personally don't trust it 100% I never trust software and computer devices for safety purposes if I can help it. And as you stated, you cannot physically interrupt power between the VFD and motor, else you may damage the VFD. It needs a load attached at all times (at least from everything that I've read about it).

So for my unit, I actually wired an E-stop to interrupt the 220 VAC single phase power IN to my VFD. That way it physically chops power to the unit and absolutely turns it off, irrespective of any weird malfunction that might occur with the VFD. Plus it doesn’t hurt the VFD to cut power in this fashion. It also conveniently puts the green power-on button next to the E-Stop button right there on the head so I don’t have to reach behind the machine to turn it on. Plus I ran the VFD's detachable control panel (which many of them have) and used a ribbon extension cable to co-locate the control panel conveniently in the same box as the E-stop button. Works great.



So for my unit, I actually wired an E-stop to interrupt the 220 VAC single phase power IN to my VFD. That way it physically chops power to the unit and absolutely turns it off

Then, it's not an E-stop because it doesn't brake the spindle. What you have is just an off switch. Sorry, worked too much in safety.
Here's how I did mine. FWD/Off/REV on switch, same as BP. I programmed VFD to coast so that I can use the hand brake. Just like running a stock machine. VFD is mounted on the rear of the machine.
Thanks for your answers to my questions. If anyone has any more to add, please do.

Ok, so now here is what I am thinking. I will have two panic type stop buttons. One will be a "shut off ALL power" button. It would shut off power to the VFD input and to the control input, and would only be used for emergency purposes (no automatic motor braking) but ALL power would be off.

The other button would be a button that would leave the control and the VFD running but would turn off power to the spindle (controlled stop) and all the servo motors. This is the button that would get hit when the control was telling the servos to do something other than what I wanted (for example). The second button would be the one that would be used more often since an incorrect programmed move could cause a physical crash or some other bad thing.

There would also be the normal forward/stop/rev switch for the spindle motor for normal operation.

Does this sound reasonable?

Also, for those interested, I should have given a bit of my background and where I intend to go with this machine. I am retired. I worked programming jet engine transient dynamic simulations and control software. I bought the machine with the Anilam control to keep me busy, happy, and just as important to be out of my wife's hair. The Anilam control does work except for the RS232 interface so I have to sit at the machine and type info into the control line by line.

My plan is to replace the Anilam control system with my own homemade one. Depending on how deep I go with that, it could keep me busy for quite some time. But the good thing is I do have something working now and am able to use it (once I get a VFD hooked up) to make or fix "stuff". I can also use it manually as well. This just seemed like the perfect project given my interests. In the meantime, I would like to get the RS232 going if possible to make it less painful to use the current control system.
If you want true e-stop, then you would need to interrupt power to the motor and release a spindle brake that is held open by a solenoid. Any other system requires some active controls such as applying DC to the motor. At the same time, you would need to e-stop the controller.