Introduction to the principle of phase shifter

Oct 15, 2021

A device used to adjust the phase of AC voltage. The phase shifter is generally multi-phase, and its structure is shown in Figure 1. It is similar to a wound three-phase asynchronous motor that is rotated. Usually the stator winding is used as the primary winding, and the rotor winding is the secondary winding. A set of worm gears is installed on the rotor shaft of the phase shifter. Rotating the worm gear can make the rotor of the phase shifter rotate within a certain range relative to the stator. When the primary winding on the stator is connected to a three-phase AC power supply, the rotating magnetic field generated in the air gap will induce electromotive forces E1 and E2 in the primary and secondary windings, respectively. Its size is proportional to the effective number of turns of each winding, and the phase is determined by the relative position between the primary and secondary winding axes. For example, the axis of the primary and secondary windings are different from each other in space by α electrical angle, ignoring their leakage impedance voltage drop, the relationship between the primary and secondary voltages can be obtained as U1≈-E1

Where nsr is the transformation ratio of the primary and secondary windings. Changing the position of the rotor can change the phase of the secondary voltage relative to the primary voltage, but the output voltage remains the same.

The phase shifter organically combines transformer phase shifting technology with digital measurement technology. The phase shifting adjustment accuracy is high, the reading is accurate and intuitive, the output voltage and current are adjustable, the output waveform is good, the operation is reliable, the operation is convenient, and it can meet high accuracy. The single-phase and three-phase AC power, phase and other instruments of the test calibration can also be used in the verification device of the watt-hour meter.

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