The standard practice is to wire the CTs and VTs with conventional polarity connection, meaning that the primary CT polarity should be placed away from the primary protected device and that the secondary CT polarity terminal should be connected to the polarity terminal of the relay. The standard practice is to wire the CTs and VTs with conventional polarity connection, meaning that the primary CT polarity should be placed away from the primary protected device and that the secondary CT polarity terminal should be connected to the polarity terminal of the relay. Even a minor mistake in polarity can lead to false tripping or failure to detect internal faults in transformers, generators, or busbars. In this guide, we will explore everything you need to know about CT polarity in the context of differential protection. This includes technical insights. Abstract—Validating proper current transformer (CT) and voltage transformer (VT) wiring, terminations, and grounding is fundamental to successful performance of the protection system. Occasionally, errors in CT and VT connections can occur, such as missing or broken neutral wires, multiple or. SEL and GE's relays let you set the polarity in the relay. If you can't explain it to a six year old, you don't understand it yourself. This engineering brief explains how these features affect relay wiring and operation in a PLC-based control system and answers a common. CT star-point is towards the line or towards the busbar.