ABSTRACT
This chapter deals with checking of phase sequence at time of initial inspection and testing. For three-phase systems it is important to have knowledge of the phase rotation of the supply and at various points within an installation. It is convention for this rotation to be normally Brown, Black, Grey, or L1, L2, L3. The direction of three-phase motors can be reversed simply by reversing any two phases. In consequence the correct sequence is essential to ensure the right rotation. Paralleling of two three-phase generators or of a generator to the three-phase public supply system requires their phase sequences to be synchronized. The instrument is simply a small three-phase motor with a dial that indicates in which direction the supply is rotating. The testers are designed for single-phase use, where a value of Prospective Short-Circuit Current (PSCC) required for three-phase system is determined.
