The phase sequence meter is used for the detection of phase sequence in three phase circuits and there are different types of phase sequence. A phase sequence detector to detect the change in phase sequence is given in a recent paper (ref. 1) using sequential circuit logic design and. The Models B (50/60 Hz) and Model C ( Hz) Phase Sequence Detectors permit the operator to quickly and easily determine proper phase sequence.


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When a three phase supply is given to the coils, then the coils will produce a rotating magnetic field, and this rotating magnetic field produces eddy EMF in the rotatable aluminum disc, as phase sequence detector in the diagram.

Phase Sequence Meter and Its Working Principle

This eddy EMF produces eddy current on the aluminum disc, due to the interaction of the eddy currents with the rotating magnetic field a torque is produced which causes phase sequence detector aluminum disc to rotate. The clockwise direction rotation of the disc indicates the sequence as RYB, and the anti-clockwise rotation of the disc indicates the change in phase sequence.

Static Type Phase Sequence Indicator Static Type Phase Sequence Indicator with inductor If the phase sequence is RYB, then the lamp B will glow brighter than the lamp A, and — if phase sequence is reversed — then the lamp A will glow brighter than the lamp B, as shown below in the lamp arrangement circuit diagram.

We know that the phase sequence detector sum of all phase currents is equal, phase sequence detector we can get the below equation.

It indicates that the voltage at the lamp A is only 27 percent of the lamp B.

Phase Sequence Meter and Its Working Principle

So, from this, we can observe that the lamp B will glow brighter than the lamp A in case of an RYB phase sequence. While in case of a reversed phase sequence, the phase sequence detector A is brighter than the lamp B.

phase sequence detector Similarly, from the above circuit by replacing the inductor with a capacitor, as shown in the below figure, the indicator works similar to the above phase indicator. Here two resistors are connected in series with the two Neon lamps to protect the lamps from over current and breakdown voltages.

Phase Rotation Meter 70V to V | PD - Hioki

If the three phase supply is in the sequence of RYB, then phase sequence detector lamp A will be ON, and the lamp B will be off, and if the supply sequence is reversed, then the lamp A will be off while the lamp B will be on.

Phase Sequence Checker For a better understanding of this project, here we have designed a phase sequence checker project to phase sequence detector the phases of three phase supply. As we know that, if the three supply phase sequence is changed or reversed then the loads like the three phase motors will operate in phase sequence detector direction which may lead to permanent fault.

So, in order to detect the phase sequence, the three phase sequence checke r is used which consists of NAND and OR gates. If the sequence is proper, then the LEDs will run clockwise as they do not receive triggering signal from the gates. If the sequence is changed, then the gates generate the input signal to the microcontroller through a timer to drive the LEDs such that these indicate the change in phase sequence by running clockwise for sometime and anticlockwise for sometime after receiving the triggering signal.

In this case, we can maintain continuous supply to critical load by using auto selection of any phase available in three phase supply system.


This is about the phase sequence meter types and working with a practical implemented circuit. We can not assume the phase sequence phase sequence detector detecting them. To change the phase sequence of the supply side we have to detect it first ….

  • What is the easiest phase sequence detection circuit for three phases? - Quora

There are two types phase indicator meter. Rotating type Static type phase indicator Rotating type phase indicator — The main principle of rotating type phase indicator is same as the three phase phase sequence detector. An aluminium disk is placed.


The opposite rotation of that disc say clockwise indicates negative phase sequence of the supply side can be R-B-Y.

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