Wiring HuangYang VFD without grounding! How dangerous is this?
Hello all,
I have a huge noise problem with Huanyang VFD. I use PlanetCNC-Mk2/4 and the USB connection gets lost when I turn on the power output on the VFD.
I have tried many many things, star grounding, moving things around, using a different power outlet to power up the single phase VFD but without success.
I also have a huge EMI filter (make in switzerland :P) just before the VFD's AC power input.
Also I have shielded wire on the VFD to spindle line, which is connected to VFD earth terminal (and NOT on the spindle, somewhere I read that it should be connected on one side only)
If I disconnect the earth-ground wire from the VFD terminal it seems that everything is working, but this way the VFD is floating.
First, how dangerous this stuff is.
I mean the whole cnc router is grounded, and I guess I won't get into crazy shocks in case of any shorts.
Any other reason this is a bad idea?
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Re: Wiring HuangYang VFD without grounding! How dangerous is this?
Some thing is not right, Bonding everything to the service ground at a common star point should be done.
The shielding can be connected both ends, but you need a separate earth ground conductor from VFD to spindle, and the spindle frame has to be at ground.
Did you check the spindle frame for ground potential? Some spindles do not have the earth connector terminal actually connected to the frame.
Al.
CNC, Mechatronics Integration and Custom Machine Design
“Logic will get you from A to B. Imagination will take you everywhere.”
Albert E.
Re: Wiring HuangYang VFD without grounding! How dangerous is this?
You need a shielded USB Cable with ferrite's at each end, this may be one of your problems if you don't have a cable like thisOriginally Posted by takeda
It sounds like you may have a Ground loop, that will cause this problem
It is obvious you don't have it wired correct, the Ground is very important, and must be in place, most likely your wiring from the Spindle to the VFD could be one of the main places there is a problem
The Shield if that is what you are referring to, has to be connected at both ends, this has to be done correctly or it will be ineffective, take some photos of how you have wired all the connections ( close up shots ) and post them here, and I will help you get it corrected
Mactec54
Re: Wiring HuangYang VFD without grounding! How dangerous is this?
Is your PC power supply ground connect to the star point?
The PC MoBo ground plane and DC common is connected to earth ground conductor, so ensure this is bonded correctly.
Al.
CNC, Mechatronics Integration and Custom Machine Design
“Logic will get you from A to B. Imagination will take you everywhere.”
Albert E.
Re: Wiring HuangYang VFD without grounding! How dangerous is this?
I will add photos...
I assume in my current setup that a power strip acts also as the common ground reference.
One thing could be that the power supply of the PC is low quality (no EMI filter).
As for the USB cable, I already use double shielded cable (as in the picture).
Meanwhile as you said, I will try to find the ground loop.
Re: Wiring HuangYang VFD without grounding! How dangerous is this?
Here is the drawing. Much better than pictures, I cannot take photos of everything.
If I connect the EARTH wire coming from the power strip to the E terminal on the VFD, the moment I turn power output of VFD on I loose USB connection.
If I disconnect the EARTH wire from the VFD everything works but the VFD is floating.
On the shielded cable for the spindle, the shield is connected on the VFD side to EARTH terminal and on the other side is unconnected.
Any ideas?
[PS1. On the VFD, the E and Ground/Earth symbol are the same terminal, connected to spindle cable shield and power outlet EARTH)
[PS2. I forgot the EMI filter just before the RST terminals of the VFD, but nothing special typical in series connection]
Last edited by takeda; 05-30-2018 at 02:45 PM.
Re: Wiring HuangYang VFD without grounding! How dangerous is this?
Do you have a Ground wire from the VFD to the Spindle Ground wire connects to the Pin 4 in the spindle plug, check the Pin 4 for continuity to the spindle body, these some times are not connected and have to be connected by removing the Cap on top of the spindleHere is the drawing. Much better than pictures, I cannot take photos of everything.
If I connect the EARTH wire coming from the power strip to the E terminal on the VFD, the moment I turn power output of VFD on I loose USB connection.
If I disconnect the EARTH wire from the VFD everything works but the VFD is floating
On the shielded cable for the spindle, the shield is connected on the VFD side to EARTH terminal and on the other side is unconnected.
Any ideas?
[PS1. On the VFD, the E and Ground/Earth symbol are the same terminal, connected to spindle cable shield and power outlet EARTH)
[PS2. I forgot the EMI filter just before the RST terminals of the VFD, but nothing special typical in series connection]
All the Ground wires need to go to ( 1 ) Point
Mactec54
Re: Wiring HuangYang VFD without grounding! How dangerous is this?
I checked, but there is no coneection inside for the 4th pin.
Anyway, I did the following today:
- I connected the EARTH from the power strip to the E of VFD.
- I disconnected the E of VFD from the shield of the spindle cable.
- I grounded my machine (and spindle casing) to EARTH of the power strip.
This way the planet cnc does not seem to lose connection when I turn on the spindle. But I didn't run any long program to check this out yet.
If I connect the E of VFD to the shield of the spindle cable I get (I assume) a ground loop and this causes the main braker to switch off (I apologize I don't know how to say this in english, no power in the whole garage)...
Re: Wiring HuangYang VFD without grounding! How dangerous is this?
A ground loop only occurs when a potential difference occurs between two earth ground points, if the earth (GND) conductor is completed from supply to motor frame then this is equi-potential bonding and allows the grounding of each end of the VFD conductor shield.
Al.
CNC, Mechatronics Integration and Custom Machine Design
“Logic will get you from A to B. Imagination will take you everywhere.”
Albert E.
Re: Wiring HuangYang VFD without grounding! How dangerous is this?
That is not how to Ground your spindle
Ground /Earth wire, spindle to VFD, VFD to main Power Ground /Earth your power strip, or a star point where all the Grounds /Earth wires should connect, you will have to fix the 4th pin in the spindle like what I posted
If the main Breaker turns off, then you have a more serious problem, you have an electrical short, so check in the spindle plug that there are no wires touching
Mactec54
Re: Wiring HuangYang VFD without grounding! How dangerous is this?
Well I don’t get it.
What do you mean spindle to vfd. Earth runs through shield or I should have a 4 core cable. And if so where does shield connects to?
Furthermore, What’s the difference of adding a screw inside the spindle compared to putting earth on the connector? It’s conductive and its the same thing. I checked with multimeter.
Also the VFD has only one earth terminal, should I use that for connecting to mains earth and spindle ground? And if so when you ground the whole machine to earth don’t you create a loop?
Anyway if somebody could just create a drawing I allm sure it would help others as well
As for the short, I will ofcourse check again tomorrow thoroughly but It could be caused by the earth wiring, I will explain with a drawing
Re: Wiring HuangYang VFD without grounding! How dangerous is this?
The short is Not caused by the Ground /Earth wiring
This is where your problem is the Shield is not a Ground / Earth and yes you need to have a 4 core cable Plus Shield
Mactec54
Re: Wiring HuangYang VFD without grounding! How dangerous is this?
Well the tripping was caused by Ground wiring and I don't understand why I need a 4core cable in principal.
If you could explain the whys it's fine, I am all along.
But I will explain why I am saying this:
First, The breaker tripped because I was powering the VFD from a different outlet at that time in the garage, the Earth conductor from the VFD to mains panel generated a voltage difference on the VFD E(E) that was detected as voltage difference in the mains panel. Ground loop. Checked out no shorts. So forget this, let's say I should stick to star grounding scheme.
Second, In three phase systems you don't need neutral, while you need Ground for safety, buy current won't flow through Ground in normal operation, and in case of fault the breaker will trip of. Also the shield to act as a cage, should be grounded.
While it better to have a separate conductor for Ground, it's not related to my problem. And your diagram does not explain where the shield connects to. The VFD is plastic enclosure. If shield is not Ground, where do you connect it at?
Re: Wiring HuangYang VFD without grounding! How dangerous is this?
You must earth your motor/spindle.....by using the fourth core of your four core cable. If you using a three core cable then you have the wrong cable. Shielding is not to be used in place of your earth conductor. Shielding around the cable is used to stop the noise generated by the drive output to reach other control cables in the area. Connect the shield and the earth conductor together at the motor
Re: Wiring HuangYang VFD without grounding! How dangerous is this?
My spindle Is EARTHed but not through a 4 core cable. The whole machine is connected to ground, so the spindle as well (everything aluminum/steel conductive)!You must earth your motor/spindle.....by using the fourth core of your four core cable. If you using a three core cable then you have the wrong cable. Shielding is not to be used in place of your earth conductor. Shielding around the cable is used to stop the noise generated by the drive output to reach other control cables in the area. Connect the shield and the earth conductor together at the motor
The spindle case is grounded but not through the connector.
Where is the problem with that? :-)
Please with explanations, not only "do that" :P
(Honestly with friendly/fact seeking mood)
Re: Wiring HuangYang VFD without grounding! How dangerous is this?
I am just telling you how we do it in the industry.....i am not going to go into the legal or technical reasons why we do it this way. It's up to you whether you choose to follow industry/legal standards or not.
Earthing the metal parts are referred to as "bonding". Bonding of metallic parts are done to protect the user in case any of the metallic parts becomes live when a fault occurs.
Re: Wiring HuangYang VFD without grounding! How dangerous is this?
Please be aware that some drives may cause the safety supply to trip.....this is caused by the harmonics being generated back into the mains supply by the drive. So your 30mA safety breaker may trip
Re: Wiring HuangYang VFD without grounding! How dangerous is this?
It is obvious that we can't help you as you seem to no a better way of doing things, which is incorrect, I would suggest you contact an electrician or a electrical inspector, before you cause some harm to yourself
Your Spindle is not Grounded / Earthed through your machine, unless each component had it's own Ground / Earth wire, there are to many moving parts for it to have a correct Ground / Earth connection
The electrical code requires you to use a 4 Core shielded cable for all VFD Drive installations
The Shields are Grounded / Earthed to the Ground / Earth plane, this is the metal plate that all you parts are mounted on, this Plate has a Ground /Earth stud being the Star Ground Point
Mactec54
Re: Wiring HuangYang VFD without grounding! How dangerous is this?
Very well said Mac
Re: Wiring HuangYang VFD without grounding! How dangerous is this?
If it's tripping your breaker, you probably have a severe fault that is extremely unsafe.
Circuit breakers do not monitor ground/PE. Ground fault breakers just make sure that the same current is flowing through hot and neutral. If the amount of current out isn't equal to the current coming back there's a ground fault and the breaker trips. In this case, there is probably a neutral connected to PE, which is considered a ground fault. If your breakers are ground fault type, the fault probably won't kill you.
If your breaker that's tripping is not a ground fault type, it means it's simply an overcurrent fault. This most likely means that you have hot connected to ground. If you leave this ungrounded and happen to touch it, it may very well kill you.
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