FR-E700 Inverter error codes can be found under troubleshooting section of the manual (attached). This section looks specifically at the Fault 7 based drive failure.
Error E.7 Details
As can be seen this error is related to electrical noise, external the VFD applicable, which cause the drive to trip. This electrical noise is also known as RF\EMC or Harmonic induced noise.
Noise mitigation is to be applied, such as the application of filters. Alternatively, another power source can be considered.,