What is the need of polarity marking in polyphase AC circuits?

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What is the need of polarity marking in polyphase AC circuits?

Need of Polarity Marking in Polyphase AC Circuits: i) Polarity marking of terminals provides reference polarity for better understanding of system, even if the polarity of ac voltage changes continuously with respect to time. ii) Making connections for parallel operation of transformer becomes easy if the terminals are polarity marked, otherwise winding may get connected with additive polarity and high circulating currents may damage the windings. iii) Polarity marking is a convenient way of stating how the leads are brought out. iv) Without polarity marking, it is difficult to understand the terminals, phase displacement, phase sequence in polyphase circuit. v) Without polarity marking in polyphase circuit, there will be lot of confusion in making the connections. vi) Without polarity marking in polyphase circuit, making connections of current transformers in relay protection circuit and getting desired performance is very difficult.

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