How to phase overhead lines

How to phase overhead lines

Phasing is also called nuclear phase, which measures whether the ends of the line conductor are the ends of the same conductor, so as to avoid phase-to-phase short circuit accidents after power is sent. Usually, all newly built or rebuilt lines must be phased before power transmission. There are two common methods for phase setting:

(1) Megohmmeter method: connect the three-phase A, B, and C wires on one side of the line to the L end of the megohmmeter, and the wires on the other side are grounded, and slowly shake the megohmmeter handle. If the pointer points to the “0” position, the L-terminal wiring is the same phase as the wire grounded on the other side of the line, otherwise, it is different phases.

(2) Single-phase voltage transformer method: suitable for chargedPower Grid. Voltage transformerWiring diagramAs shown in the figure. The voltage values ​​of AA’, AB’, AC’, BA’, BB’, BC’, CA’, CB’, and CC’ are read from the secondary side of the voltage transformer respectively. If the voltage is zero, it means that the two terminals are in phase; if the voltage is line voltage, it is out of phase. Since it is live measurement, reliable safety measures should be taken and relevant regulations on live operations should be followed.