Request you to suggest us a part to measure 115 Volts AC, 3 Phase at 400 Hz.
Please confirm us it will work at 400 Hz.
For measureing a 3 phase system at 400Hz I would recommend using a part such as the ADE7858A or ADE7868A if you want to use CT's to measure the current. If you rather use shunts for the current measurement then I would recommend the ADE7978 with the ADE7932 which has integrated isolation.
For the ADE7858A, the data sheet is based on the fundamental being between 45Hz and 65Hz. Although, there is a bandwidth specification for energy and RMS, which is 2kHz. This means that with a 400Hz fundamental, you will only measure about 5 harmonics within that bandwidth. If the metering IC has any fundamental or THD measurements, such as the ADE7878A or ADE7978, these measurements will not be accurate because the system will be looking for a 50 or 60Hz fundamental to base these measurements off of.
Many specifications from the table in the data sheet refer to a specific fundamental frequency between 45Hz and 65Hz but you should still expect similar performance at 400Hz besides what I mention above.