Current Transformer: A deeper dive
Installation and polarity of a current transformer. Since current transformers are used on AC circuits and the direction of the current in an AC system is constantly changing, the polarity of the transformer terminals also changes on each cycle. One might easily think that current transformers like most AC devices have no polarity. If you follow this assumption, you would be wrong because transformers have polarity. The Polarity of a CT is very important when installing them for relay protection and metering. The polarity of a CT is determined, by the direction in which the coils are wound, around the CT Core, and how the secondary leads are brought out of the transformer case. However, whenever we talk about the polarity of a transformer, we are referring to the instantaneous polarity. In essence, the polarity markings on the current transformer denote the instantaneous polarity of the transformer. The easiest way to understand this is by using the dot convention. From the diagram b