- Joined
- Dec 8, 2013
- Messages
- 2,651
Good point, but the important thing to do is to connect it to the motor frame (which should be grounded for safety but might not be).
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VFD Problem
- Thread starter Great white hunter
- Start date
Good point, but the important thing to do is to connect it to the motor frame (which should be grounded for safety but might not be).
- Joined
- Jan 14, 2013
- Messages
- 62
I figured it out The parameters were set correctly but I was running at 1000 rpm at only 30HZ I ramped it up to 60hz and it works great.
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I figured out my problem with the VFD but now I have a new problem. I noticed when I had my arm resting on the machine I could feel current going into my arm. What do I have to ground to fix that. Thank you Jason.
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I figured out my problem with the VFD but now I have a new problem. I noticed when I had my arm resting on the machine I could feel current going into my arm. What do I have to ground to fix that. Thank you Jason.
I figured out my problem with the VFD but now I have a new problem. I noticed when I had my arm resting on the machine I could feel current going into my arm. What do I have to ground to fix that. Thank you Jason.[/QUOTE]
That is the back EMF issue with VFD's I noted in my last post. It is not electrically induced it is magnetically induced from the rotor to the motors case. Inverter Duty motors have the shaft grounded one way or another -- electrically conductive grease or a brush of some sort.
You absolutely have to have the VFD Input grounded by running L1-L2-Gnd from your power panel -- and it needs to be a real "Earthed" ground in your panel. The whole machine -- Lathe, Mill, etc, must be bonded to this same ground. Then the VFD to the motor must have a ground by running L1-L2-L3-G. This may or may not solve the issue. I suspect maybe not. Been down the road before. When running, you can take a volt meter and measure a significant voltage from the motor shaft or case to ground. Generally not lethal, but very annoying. I have eventually replaced all my motors with Inverter Duty Motors and don't have the problem.
You can verify that you have a ground by measuring the voltage from any hot leg to ground. You should get 120 Volts or so. If not you do not have a good ground.
You can reduce the effect by lowering the carrier frequency, but the added effect is heat and only helps a bit. If it is still an issue after you have verified everything is well grounded then maybe figure out a way to make a brush to your motor shaft with some stranded copper wire just rubbing on the shaft / pulley, etc, and attached to the common VFD frame ground. That will make it go away.
The same phenomenon occurs with the High Frequency Arc Starters on Plasma and AC TIG, where you need to ground half the metal items in your shop or you can get a nice tingle just touching something metal and something that has does have a ground.
Peter
That is the back EMF issue with VFD's I noted in my last post. It is not electrically induced it is magnetically induced from the rotor to the motors case. Inverter Duty motors have the shaft grounded one way or another -- electrically conductive grease or a brush of some sort.
You absolutely have to have the VFD Input grounded by running L1-L2-Gnd from your power panel -- and it needs to be a real "Earthed" ground in your panel. The whole machine -- Lathe, Mill, etc, must be bonded to this same ground. Then the VFD to the motor must have a ground by running L1-L2-L3-G. This may or may not solve the issue. I suspect maybe not. Been down the road before. When running, you can take a volt meter and measure a significant voltage from the motor shaft or case to ground. Generally not lethal, but very annoying. I have eventually replaced all my motors with Inverter Duty Motors and don't have the problem.
You can verify that you have a ground by measuring the voltage from any hot leg to ground. You should get 120 Volts or so. If not you do not have a good ground.
You can reduce the effect by lowering the carrier frequency, but the added effect is heat and only helps a bit. If it is still an issue after you have verified everything is well grounded then maybe figure out a way to make a brush to your motor shaft with some stranded copper wire just rubbing on the shaft / pulley, etc, and attached to the common VFD frame ground. That will make it go away.
The same phenomenon occurs with the High Frequency Arc Starters on Plasma and AC TIG, where you need to ground half the metal items in your shop or you can get a nice tingle just touching something metal and something that has does have a ground.
Peter