VFD is blowing my RCD

[Mr*Beaver]

Good evening,

I'm working on my first CNC build previously I have used and heavily modified a shapeoko. I'm in the final stages of my build (putting everything back in the garage and tweaking). Over the weekend I took my 2.2kw Chinese spindle and Huanyang off my shapeoko and fitted it. Thinking this would be a simple job I hooked it up the same way it had been connected.

The PWM going to the VI, ACM going to ground and DCM and For shorted - upon stating a job it would start and stop on stop.

Now I'm running of an Arduino mega board with external drivers and electronics. When the For and DCM are shorted if I turn the power of the VFD my RCD will blow within a few seconds.

I then shorted with a 2k resistor which actually worked. However I have been told I should use a relay. I went off and bought a 5v low voltage trigger relay rated at 10a 240v and now have that hooked up with For and DCM being linked when the relay is triggered.The relay is powered from the USB powered ardunio. Whilst this works if my usb disconnects for any reason my RCD trips. It's almost as if the surge of the power stopping is triggering the rcd, and previously it was the surge of it starting.

I've had the same vfd and spindle setup for almost a year and not had this issue.

In an ideal world this would not happen. I really don't like tripping the power in my house even if it is a unlikely situation/cause.

And here is a picture of my build :D it has a 80 x 80 x 15 cut ability. I designed and cut the entire frame on my shapeoko 3.

[A_Camera]

I have to admit that I have no idea what VI, DCM, For and ACM are. Please make a drawing to show what you connected to what and more details about the resistor and the relay. Perhaps post relevant pictures and not the whole machine which does not give us a clue about the possible problem.

[Mr*Beaver]

Here is a wiring diagram it's a little poor as I'm on a bumpy train.

[Doddy]

There's a lot of ambiguity with the OP's description.

Firstly, how have you connected an Arduino PWM output to the VFD? I'm guessing this is a run-of-the-mill HuanYang VFD - no-where in the manual describes setting this up for a PWM input (ref. configuration parameters PD002 and PD070). You mention some external drivers and electronics, is this providing the PWM to analogue conversion?, details please.

Let's get back to basics. Isolate the Arduino. Just have two switches - connected between FOR and DCM (this is your On/Off), and between VR and VI (this is your 0/100% speed control), set PD002 to 1 (default = 0) and PD070 to 0 (default). Then test the behaviour using just these. If your problem goes away then it's nothing to do with "surge of power".

I've had the same vfd and spindle setup for almost a year and not had this issue.

So what's changed?

and previously it was the surge of it starting

I've read the description a couple of times. Maybe too early in the morning for me but I can't see where you discuss starting problems.

I hooked it up the same way it had been connected.

Let's have a look at the wiring diagram for this.

Also, please confirm that you've earthed the VFD.

I don't always agree with A_Camera but just this once - yeah - please post some relevant photos of the wiring to the VFD, and confirm the PD002 and PD070 settings.

[Mr*Beaver]

I've posted a basic wiring diagram but the post is waiting to be approved.

The arduino is an analogue signal between 0-5v. The vfd takes this and sets the speed based on the voltage provided. Dcm and for need to be connected for the spindle to turn on.

Vd002 is set to 1, vd070 is currently set at 1. I did try using frontal controls and had no issue when using the start/stop button on the vfd.

The main change is the board I'm using, the shapoko board wasn't suitable for this build.

The vfd is earthed, so is the spindle and the arduino board.

[Doddy]

I've posted a basic wiring diagram but the post is waiting to be approved.

The arduino is an analogue signal between 0-5v. The vfd takes this and sets the speed based on the voltage provided. Dcm and for need to be connected for the spindle to turn on.

Vd002 is set to 1, vd070 is currently set at 1. I did try using frontal controls and had no issue when using the start/stop button on the vfd.

The main change is the board I'm using, the shapoko board wasn't suitable for this build.

The vfd is earthed, so is the spindle and the arduino board.

Thanks for that.

Firstly - has this behaviour started when you connected the arduino and configured the VFD for 0-5V operation? Or did it start when you move the machine into the garage? (or did you big-bang both changes together?)

Particularly relevant to the problems being encountered during the move to the garage: I'd be inclined to examine your RCD and understand if it's a Type-A or a Type-B - the latter being recommended for frequency convertors (e.g. VFD). Google the two types to understand more if you want to pursue this.

If the problem was introduced by the Arduino - then, first-off you know the Arduino analogue/PWM outputs are not analogue outputs, but a digitally switched 0/5V PWM output?, I've not seen anything that gives me confidence that this would work directly connected to the ACM/VI input to the VFD. If it does, then it's likely more by luck than by design. Normally you connect a PWM output through some form of integrator to generate the analogue output (many cheap BoBs provide this functionality - and that might be an option to explore). My thoughts are around what the VFD may be trying to do with an VI input that alternates 0/5V a thousand times a second. One thought - flash the arduino to set the PWM output to ONLY 0% or 100% (and no-where in between!) - or better still remove any of the PWM initialisation and drive it as a discrete output - again, only 0 or 1. If that cures your problem then it's the PWM behaviour that's the problem and is resolvable. If you don't fancy changing the code, then pull a 5V supply from the arduino and drive that into the VI input, instead of the PWM drive - you'll only have on/off control, but it'll help isolate the problem.

If you try the above and the problem remains (with the VI connected only to 0V or 5V) then... try disconnecting whatever PSU you're using to drive the arduino - power it through the supply socket using a PP3 battery (it won't last long!) - if that cures the problem then I'd be inclined to dump the USB PSU that you're driving the ardy with (I'm thinking what can cause an earth-leakage the the RCD is picking up)

[Mr*Beaver]

Hi Doddy, thanks for coming back.

Unfortunately I next tested the spindle whilst the machine was in the living room being built, however the spindle never caused me an issue in the past so when I swapped it from one machine to the next I thought nothing of it. That was till I blew the power. It's also why I'm ruling out wiring the spindle wrong etc and I have seen it working. I did however run the spindle on a different circuit whilst in the garage and had the same result.

I don't believe it is my RCD as I haven't had any random trips in the past and have been using this VFD and spindle in the past. I do know it has something to do with the arduino board - as really thats the only thing that has changed.

When I initially wired it up I found multiple people who had connected it in the way I describe. I can control the speed to the nearest 1000rmp - from the instructions it does state 'Analog Voltage Frequency Reference Input' I'm not sure it's a true PWM input? However looking at the manual I could also try hooking it into the AI terminal? I'd need to check the current is between - 4~20mA.

I will try feeding a 5v input into it, I like that idea as it should tell me is the issue lies with the PWM/gnd or the DCM/For enable spindle.

Do you think it's worth me grounding the machine earth through an additional power supply? Currently it runs through the laptop power.

[komatias]

Mine was blowing the RCD. The spindle motor was shorting.

Also it may be the EMF filter inside the VFD that trips it. I think these can be disconnected on most units.