Just for fun
PSI-1 phase sequence indicator, in your browser Beta
Connect the three leads to a three-phase supply and watch the disc. Swap two leads, lose a phase, drop the voltage, or tilt the instrument, and see what a motor would do on that supply.
Beta, just for fun. This is a playful beta, for illustration only. It is not a training tool and not a substitute for the real instrument. The actual PSI-1 can differ in appearance, display, button behaviour, ranges, timings and readings. Everything here is simulated, so do not use it to judge a real measurement. Always follow the instruction manual and your site safety procedure.
Beta · just for fun
Use the panel to connect the leads. Keys: S swap two leads.
Try a scenario
1The supply you are checking
2Connect the leads
Swap two leads
3How you hold it
4What it is telling you
5Simulator settings
Reset everything
How a phase sequence indicator works
- What it checks: the order in which the three phases of a supply reach their peak, called the phase sequence. Connect a motor to the wrong sequence and it runs backwards, which can damage pumps, fans, compressors and conveyors.
- How the disc works: three coils produce a magnetic field that rotates in step with the supply. The rotating field drags the lightweight metal disc around with it, and the direction of the disc shows the direction of the field. In this simulator, clockwise means R, Y, B (the normal, positive sequence) and anticlockwise means R, B, Y.
- Swap two leads and the disc reverses. That is the quick fix at a motor terminal box too: swapping any two supply leads reverses the motor.
- Lose a phase or short two leads together: there is no rotating field, so the disc does not turn steadily. A motor on that supply would hum and overheat.
- Voltage and frequency: the PSI-1 works from 100 to 500 V AC and 25 to 65 Hz. Below 100 V the torque is too small to turn the disc reliably.
- Hold it flat: the instrument is made to be used horizontally. Held upright the disc leans on its bearing and does not turn properly.
- Safety: you are connecting to live three-phase supply. Use insulated leads and clips, and follow your site's safe working procedure.
This is a playful beta simulation. Which way the real disc turns for a given sequence, and the exact speed, depend on the instrument and are approximated here (clockwise shown for R, Y, B). Always follow the instruction manual and the markings on your instrument.
Want the real thing on your bench?
The PSI-1 is made and supplied by CIE in Howrah, with test certificate available on request.