Arcteq’s patented measurement algorithm with frequency tracking between 6 and 75 Hz frequency provides for accurate protection also in challenging VFD applications. In applications with large or important motors, protection functions beyond those commonly available in VFDs may be required. Often for example differential protection should be added to speed up the protection and mitigate damages in case of winding failures. When applying multifunction relays with VFDs, both, the current transformer (CT) and protection relay behavior with lower frequencies should be well known. This is especially important when relays are installed on the load side of the VFD.


Arcteq carried out laboratory tests to verify the typical CT behavior in the case of VFDs.

The complete report can be accessed by clicking this link: Technobothnia Lab Test report