RS485 Safety

[A_Camera]

Before you do the 3 phase switch idea check in your manual about a warning to NOT install a switch between the VFD and motor. MOST have that warning.

Just a thought, (;-) TP

Still going on about this, without ANY proof? I have already discussed this with you on CNC Zone, where you made the same claim...

What one should NOT do is using that as an on / off switch. That is for SAFTEY.

[A_Camera]

+1
A cliff of one or more cables between the motor and the VFD will lead to the combustion of the VFD keys.
If you really make the chain rupture, then on the VFD power line.

WHAT....?

Are you sure you know the subject...?

[A_Camera]

YES it can be switched between motors but you use a sequence know as make before break. That means you make the AUX connection before you break the Main connection. That way there is never an open connection. It only takes 1 OOPS to blow out the final drive of a VFD.

That is my advice, your mileage may vary due to local driving conditions.

It actually takes more than one OOPS to blow a VFD (at least a decent one) or a spindle... (speaking from experience) but definitely not a good idea to switch with power on, regardless if you use a contactor or a manual circuit breaker.

My advice is that you find out facts BEFORE you give advice. But sure, "your mileage may vary". There is no risk in installing a safety circuit breaker, quite the opposite, that is the ONLY one providing 100% safety when it is off, except if you switch off the mains to your VFD.

[A_Camera]

This is the controller
https://www.amazon.co.uk/gp/product/B01 ... UTF8&psc=1

Avoid USB if you want reliable communication.



I am using that one since many years. Very reliable. The RS232 port of it is used for servo configuration and monitoring, the RS485 is for the Modbus to communicate with the VFD I have.

[fixebr]

Are you sure you know the subject...?

Maybe the googlе translate incorrectly translated my words? ..
In the instructions for my VFD (Delta VFD-E), it repeatedly said that bad contact, the wire break between the motor and VFD, the installation of other equipment on the line from the motor to the VFD (except for the motor throttle and filter) - may damage IGBT. Separately, it is indicated that even the break of one cable from 3 will lead to a voltage distortion, which damages IGBT.
On YouTube, a lot of video about burnt VFD for this reason.
Installing a physical interrupter on this line - a chance to accidentally cause a chain break during operation, because you have no locks from such a trigger (even vibration or resonance can create "jitter" of contacts that can be fatal). If we are talking about security, then this solution is worse than installing the same switch on the VFD power supply - where in the event of a break or accidental shutdown it will not be damaged, and simply turns off with the error "No power network".
The second point is that you put the switch to the line to the motor, on which there is a high-frequency signal. Your switch is most likely not designed for such an application. And also, it is necessary to take into account that the motor is not an ordinary load, but high-inductive, and there are other equipment requirements. For example, in my contactor for AC-1, a current of up to 32 amps is indicated, and for AC-3 there is only 17 amps. Read about it can be here: https://en.wikipedia.org/wiki/Utilization_categories

[A_Camera]

Are you sure you know the subject...?

Maybe the googlе translate incorrectly translated my words? ..
In the instructions for my VFD (Delta VFD-E), it repeatedly said that bad contact, the wire break between the motor and VFD, the installation of other equipment on the line from the motor to the VFD (except for the motor throttle and filter) - may damage IGBT. Separately, it is indicated that even the break of one cable from 3 will lead to a voltage distortion, which damages IGBT.
On YouTube, a lot of video about burnt VFD for this reason.
Installing a physical interrupter on this line - a chance to accidentally cause a chain break during operation, because you have no locks from such a trigger (even vibration or resonance can create "jitter" of contacts that can be fatal). If we are talking about security, then this solution is worse than installing the same switch on the VFD power supply - where in the event of a break or accidental shutdown it will not be damaged, and simply turns off with the error "No power network".
The second point is that you put the switch to the line to the motor, on which there is a high-frequency signal. Your switch is most likely not designed for such an application. And also, it is necessary to take into account that the motor is not an ordinary load, but high-inductive, and there are other equipment requirements. For example, in my contactor for AC-1, a current of up to 32 amps is indicated, and for AC-3 there is only 17 amps. Read about it can be here: https://en.wikipedia.org/wiki/Utilization_categories

None of the above is relevant. To start with, if you have bad wiring than THAT is a problem. If you don't know how to connect things and how to wire your gear then maybe it would be better to ask somebody to do it for you, or buy ready made equipment with warranty. If you add six more connections it does not mean that you have higher risk for bad wiring, at least not if you know what you are doing, and if you don't know then you should not fiddle with high voltage anyway.

The second thing is once again that I NEVER said you should use this as a switch to switch the motor on or off. There is no point in explaining to me how this motor is different from other motors, I know that, I am an electrical engineer from the start and know more than 90% of the people on this forum regarding electrical wiring, safety and so on. So instead of quoting text you don't understand, you should try to read AND understand what's been asked for by the OP, and what my answer was to him.

Another point is that I am NOT saying what people should or should not do, I only show how I did it, and tried to explain why. There are far to many amateurs out there who believe that reading Wikipedia (at best) is more than enough to learn everything about electricity... well, it's not enough. That's why some of us went to schools, colleges and universities, to LEARN about it.

Another thing is that my "switch" is not a switch as you seem to understand. It is a "safety switch", and is used to ISOLATE the current source from the equipment to provide safety, not to switch on or off under load. Of course, stupid people may use it that way, but that can't be helped.

[A_Camera]

Thanks all, some food for thought I like that simple 3 phase switch idea though A_Camera

It gives you the ultimate safety if you have a good discipline. You don't need to constantly switch the VFD off and on again after tool change or probing, just flip the safety switch (when the motor is not spinning) and flip it on before issuing the start spindle command. It makes working with my hands near, or on the spindle infinitely safer. Of course, I can still cut my hands on the mill bits, but they are at least not spinning, so it will only be a clean cut, not losing a finger. The only thing you need to worry about is to flip the switch in the right order. I did miss that a few times during the years I have used this solution, but in my case, it only resulted in e very high spindle acceleration with an extreme whining noise, but of course, starting the spindle with this switch is absolutely not advisable, just like stopping it, except in emergency situation.

However, constantly switching off and on the VFD is definitely harmful for the VFD. The manual of my VFD (Bosch Rexroth) says that after switching off one must wait at least five minutes before switching it on again.

BTW, I also have a brake resistor. It greatly reduces the spindle stopping time. I don't know if you can add that to your VFD, but if you can then I'd recommend spending money on it.

[DavidR8]

I have a simpler, and in my opinion a safer solution, using a mechanical isolator, made for three phases and high current. No relays, no switching through any sofeware, just a flip of a lever up or down.



The isolator is wired between the VFD and the spindle. I switch it off every time my hands are inside the work area or when I am probing. It requires discipline, and I must remember to switch it on BEFORE the work starts, but that's fine for me, because it provides 100% protection against any accidents, which is the main thing.

BTW, I am not using Dan's plugin, but controlling my spindle entirely with Modbus and RS485 through the plugin provided by UCCNC and my own macros.

Do you have a link to this switch?

[Vmax549]

Hiya A. Just because you went to school does not mean you have any common sense . Just look at ALL the engineers that designed all of those VFDs and ALL of them say NOT to do it. Yep they must not have a brain one.

Just a thought, (;-) TP

[fixebr]

None of the above is relevant. To start with, if you have bad wiring than THAT is a problem. If you don't know how to connect things and how to wire your gear then maybe it would be better to ask somebody to do it for you, or buy ready made equipment with warranty. If you add six more connections it does not mean that you have higher risk for bad wiring, at least not if you know what you are doing, and if you don't know then you should not fiddle with high voltage anyway.
The second thing is once again that I NEVER said you should use this as a switch to switch the motor on or off. There is no point in explaining to me how this motor is different from other motors, I know that, I am an electrical engineer from the start and know more than 90% of the people on this forum regarding electrical wiring, safety and so on. So instead of quoting text you don't understand, you should try to read AND understand what's been asked for by the OP, and what my answer was to him.
Another point is that I am NOT saying what people should or should not do, I only show how I did it, and tried to explain why. There are far to many amateurs out there who believe that reading Wikipedia (at best) is more than enough to learn everything about electricity... well, it's not enough. That's why some of us went to schools, colleges and universities, to LEARN about it.
Another thing is that my "switch" is not a switch as you seem to understand. It is a "safety switch", and is used to ISOLATE the current source from the equipment to provide safety, not to switch on or off under load. Of course, stupid people may use it that way, but that can't be helped.

Now it has become obvious that Google Translate has freed my words drastically.
I do not assume that you are using your switch to "turn on or off the spindle". I did not mean anything like that. I am not an idiot and perfectly understand how our spindles work, and in electronics, I understand it well enough to understand why my VFD can burn when problems with wiring to the spindle. I have more than 15 years of experience with a different kind of powerful technique and in microelectronics.

Let's try differently.

The advantages of your chuck between the VFD and the spindle: in an abnormal situation, it will not allow the spindle to rotate, since you essentially chose it from VFD.
The cons of your chipboard between the VFD and the spindle: it may not be approached for high-grade work and high-inductive load, it may not provide an ideal connection without a rattle of contacts, it directly violates the instructions of VFD manufacturers. In addition, there you need a switch on 3 phases always, even if your VFD is connected only to one phase of the power supply (and most of the fans are working with a VFD by 2.2 kilowatt connected to a single-phase network of 220/230 volts).

Pluses of the chub between the VFD and the power supply: it will de-energize the VFD and will ensure the absence of the spindle. At the same time, it will protect VFD from problems completely, as he is de-energized.
Minuses of the chub between the VFD and the power supply: it may not be convenient if the VFD is installed in the control cabinet at the distance from the machine.

Isn't it obvious that the second way is safer and corresponds to the specified manufacturer?

And about the brake resistor: this is a good idea if you use a massive tool or your motor rotates a massive spindle with a mandrel. But for the spindle 2.2 kilowatta - it seems to me that it is too unclear. It will also stop in 1.5 seconds with active braking of VFD (without causing it heating over the measure). If you have a spindle 4-5 kilowatt and above, you will have to set the braking time of 4-5 seconds.