- Location
- San Francisco Bay Area, CA, USA
- Occupation
- Electrical Engineer
First off, as the others have said, grounding is CRITICAL to a good VFD installation. The NEC grounding requirements are only about safety, grounding requirements for VFDs are more stringent and if you get sloppy, you get problems. Ground wire back to the VFD from the motor is the most important thing, never rely on just the conduit (assuming steel), even though the NEC says that's OK.
Then next, the output cables will broadcast a signal if left unshielded. The shielding can be STEEL conduit, but if you ran cable without a shield or PVC conduit, you have a radio broadcast antenna. If it is anything other than steel conduit making the VFD to motor connection, use shielded VFD cable and ground BOTH ands of the shield, not just one end (that only applies to signal and control wiring). You are creating a "faraday cage" around the conductors, you need solid grounding of that "cage".
Last issue is the line side conductors, which can also broadcast noise. IF the outputs are all correct and you still have the noise, then you need an EMI/RFI filter. Whether or not it is a Franklin or Pentair pump, you can get an EMI/RFI filter for the line side of any VFD from people like TCI, Schaffner, MTE etc.
transcoil.com
www.schaffnerusa.com
Then next, the output cables will broadcast a signal if left unshielded. The shielding can be STEEL conduit, but if you ran cable without a shield or PVC conduit, you have a radio broadcast antenna. If it is anything other than steel conduit making the VFD to motor connection, use shielded VFD cable and ground BOTH ands of the shield, not just one end (that only applies to signal and control wiring). You are creating a "faraday cage" around the conductors, you need solid grounding of that "cage".
Last issue is the line side conductors, which can also broadcast noise. IF the outputs are all correct and you still have the noise, then you need an EMI/RFI filter. Whether or not it is a Franklin or Pentair pump, you can get an EMI/RFI filter for the line side of any VFD from people like TCI, Schaffner, MTE etc.

KRF EMI Filter - TCI, LLC
The KRF EMI Filter Limits High Frequency Noise Reduces interference Protects sensitive equipment Eliminates drive cross-talk Meet FCC Regulation 15, Subpart J Non-Linear Loads Non-linear loads can draw harmonic current from the source, resulting in harmful high frequency noise. There are many...

EMC/EMI
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www.mtecorp.com