How many CT do I need to use for the active filter?
CT’s are used with the HPS TruWave active harmonic filter (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 HPS 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
