How many CT do I need to use for the Active Filter?

CT’s are used with the HPS TruWave AHF to continuously monitor the load and harmonic currents. Typically, if the system only has three-phase loads downstream to the AHF, two CT’s can be used; the TruWave software will calculate the third phase current. If the system has any single-phase loads, a third CT is required.

Here are some the installation considerations for the current transformers (CT’s) with the AHF:

  • Must be located upstream of VFD loads requiring correction
  • Two CT’s are required for the correction of three-phase loads
  • A third CT is only required if there are also single-phase (line to neutral) loads
  • The CT’s are sized based on the current rating of the bus