This simple DIY phase sequence tester allows you to test the rotation of the 3 phases of a three-phase system. It is especially useful when connecting three-phase induction motors (if the sequence is wrong, the motor turns backwards). The indicator indicates the phase direction using two neon lamps. One lamp is for clockwise rotation and one for anti-clockwise rotation. If both lamps glow at the same time, this indicates a bad connection of the tester (connected to only 2 phases), or one phase is missing. The current of a lit neon lamp when testing the phase sequence is approximately 0.5 - 0.6 mA. The tester is suitable for 3x 380V / 400V / 415V voltages, 50Hz. For 60Hz, adjust for example the capacitor values to 3n9 OR the resistor values to 330k. Other component values can also be used, see the table below, but the resistor values must correspond to the selected capacitors. Lower resistor values and higher capacitor values will reduce the circuit impedance and thus increase the neon lamp current. For mains systems with lower voltages, it is therefore appropriate to use proportionally higher capacitances and lower resistors.
| C | R (50Hz) | R (60Hz) |
|---|---|---|
| 1n | 1.837762 MΩ | 1.531469 MΩ |
| 1n2 | 1.531469 MΩ | 1.276224 MΩ |
| 1n5 | 1.225175 MΩ | 1.020979 MΩ |
| 1n8 | 1.020979 MΩ | 850.8161 kΩ |
| 2n2 | 835.3468 kΩ | 696.1223 kΩ |
| 2n7 | 680.6529 kΩ | 567.2107 kΩ |
| 3n3 | 556.8978 kΩ | 464.0815 kΩ |
| 3n9 | 471.2212 kΩ | 392.6843 kΩ |
| 4n7 | 391.0134 kΩ | 325.8445 kΩ |
| 5n6 | 328.1719 kΩ | 273.4766 kΩ |
| 6n8 | 270.2592 kΩ | 225.2160 kΩ |
| 8n2 | 224.1174 kΩ | 186.7645 kΩ |
| 10n | 183.7762 kΩ | 153.1469 kΩ |
| 12n | 153.1469 kΩ | 127.6224 kΩ |
| 15n | 122.5175 kΩ | 102.0979 kΩ |
| 18n | 102.0979 kΩ | 85.08161 kΩ |
| 22n | 83.53468 kΩ | 69.61223 kΩ |
