S323N 3ph PSI is a lightweight, easy-to-use instrument, used to determine the phase sequence or rotation of a three-phase system. It can also detect and identify an open phase. S323N is a breakthrough in phase sequence indicators. Unlike traditional PSI, which requires the instruments’ clip to be in direct contact with bare wires to detect the phase sequence, this instrument can detect the phases through the non-contact method, which does not require the user to remove the insulation of the live wires. Simply clip the three highly inductive and insulated clips to the insulated hot wires, the instrument will instantly indicate with sound and LED light to suggests whether it is a positive or negative phase sequence. It protects the users from being exposed to bare wires, which is a much safer and convenient alternative.