I assume it's either a Franklin subdrive or Pentair Intellidrive. Both brands have RFI filters available to add on. I've only experienced this problem once on a 5 hp sub pump running on an Intellidrive PID50. You would get static on the AM radio if you were within 30-50 feet of the pump house. This system was for H2A farm worker housing and the closest building was over 100 feet away from the pump house. So nothing was done about the RFI.I have a client that only listens to AM talk radio. A VFD has been added to his well pump and is driving the radio crazy with static. Does anyone have a recommendation as to how to shield the vfd or the radio?
Heater.Doing a remodel and found a 12v transformer with a bagel looking coil of wire tied to output. Is that a sound filter for am ?
Buzz. Try again. Those filters are megahertz range to satisfy stupid Euro requirements.I assume it's either a Franklin subdrive or Pentair Intellidrive. Both brands have RFI filters available to add on. I've only experienced this problem once on a 5 hp sub pump running on an Intellidrive PID50. You would get static on the AM radio if you were within 30-50 feet of the pump house. This system was for H2A farm worker housing and the closest building was over 100 feet away from the pump house. So nothing was done about the RFI.
I want to amplify that the ground between the VFD and the motor frame is _critical_.VFDs must have stranded wiring and must have a ground between it and the motor frame. This is not optional. It is very desirable to run wiring in metallic enclosures and conduit, again properly bonded and grounded.
From the Pentair Manual:Buzz. Try again. Those filters are megahertz range to satisfy stupid Euro requirements.
Before spending valuable time and money in suppressing EMI or RFI—try the simplistic and inexpensive approach.I have a client that only listens to AM talk radio. A VFD has been added to his well pump and is driving the radio crazy with static.
Does anyone have a recommendation as to how to shield the vfd or the radio?
What is the 3 dB corner frequency?From the Pentair Manual:
"Robust EMI / RFI Filter Superior noise and interference protection (including AM radio)"
VFDs generate large current harmonics. Unless your voltage source is very close to overloaded this doesn’t matter. Current harmonics pull current through a big impedance and cause voltage harmonics, get it? Your ferrite beads are nonlinear EMI devices that block megahertz range voltage harmonics. They do nothing on the load (motor) side which if improperly installed radiated RFI not EMI everywhere. I’ve even had problems with 4-20 mA current loops because of this. That’s saying something! It takes a lot to mess those up.Before spending valuable time and money in suppressing EMI or RFI—try the simplistic and inexpensive approach.
EMI or RFI can be caused by about almost anything that we have at home.. . . even the SUN can cause this anomaly. Switched mode power supplies, electric blankets, switching loads at home, doorbell transformers , your toaster , Bluetooth units etc.
Since AM operates well below the 805.11b (FM operates higher) protocol. . . you may not be affected by its higher frequency range.
The most effective RFI suppression solution is using a SNUBBER Circuit. This type is often used by connecting a series resistor across a contact. But since you already know what’s causing it (the VFD) consider yourself lucky-- so you won’t have to do any Trial and Error trouble shooting.
The most inexpensive solution is using a FERRITE BEADS that you install at the power input to the VFD.
That’s that doughnut-like contraption that you see.. . available on line. . . cost almost dime a dozen. lol.
Good luck and keep us abreast on your troubleshooting.
It is not an engineering design manual...just the normal installation manual. Design details like that would almost never be found in a installation manual....especially one where DIY may install the equipment.What is the 3 dB corner frequency?
AM (amplitude modulation) is a "linear" modulation which means that the relative level between the desired audio signal and the noise/static (i.e., the signal to noise or S/N) is directly proportional to level of RF signal to noise (aka carrier to noise C/N). In other words, to get a 20 dB improvement in audio signal to noise (S/N) you need the RF noise from the VFD at the radio to be reduced by 20 dB. But "driving the radio crazy with static" means that the RF carrier to noise is quite low (lots of RF noise), and so the RF noise will have to be reduced a substantial amount to make the noise not be noticeable. That might be difficult unless there's "low hanging fruit" that provides easy opportunities for improvement (like no ground return from the VFD to the motor which Jon has brought up, no shielding on the conductors, etc.). Filtering of course can help, but there may be more than one path that is conducting and radiating the interference.I have a client that only listens to AM talk radio. A VFD has been added to his well pump and is driving the radio crazy with static. Does anyone have a recommendation as to how to shield the vfd or the radio?